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MICROCOPY RESOLUTION TEST CHART
MICROCOPY RESOLUTION TEST CHART
or
NAlIDNAL BUREAU Of STANDARDS·1963·A
N~.TIONAL
BUREAU
SlANDARDS·1963·A
DO
/".,JO
r LOAN
AN ILLUSTRATED SUMMARY
OF GENETIC TRAITS IN TETRAPLOID
t, AND DIPLOID ALFALFA
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Technical Bulletin No. 1370
Agricultural Research Service UNITED STATES DEPARTMENT OF AGRICULTURE Acknowledgments
Thl' authors wish to aeknowledge the cooperation of the f0110wing
persons in providing unpublished data and illustrations ineluded in thl'.
rl'port.
E. T. Bingham, formerly, Department of Plant Breeding, Cornell
Cniversity, Ithaea, N.Y.; now, Agronomy Department, University
of Wisconsin, l'.fadison .
•J. 1,. Bolton, Central Experimental Farm, Canada Department of
Av;rieultUl'c, Ottawa, Ontario.
H. L. Cart1.~~'flan, formerly, ('I'OPS Research Divi~ion, Agricultural
Research Senrice, at Nevada Agricultural Experiment Station,
Reno; now, Arnold-Thomas Seed Service, Fresno, Calif.
\V.R. Childers, Central Experimentallcal'm, Canada Department of
Agril'ulturc, Ottawa, Ontario.
W. M. Clemcnt, .1r., formerly, Crops Research Division, Agricultural
Reseal'l'h Sel'viee. at Minnesota Agricultural Experiment Station,
St. Paul; now, Department of General Biology, Vandcrbilt Uni­
versity, Nashville, Tenn.
H. ,Yo Cleveland, Agrollomy Department, Pennsylvania State Uni­
versity, University Park.
R. 1,. Davis, Agrollomy Department, Purdue lTniversity, Lafayette,
Ind.
L. Dessureaux, Dominion Experimental Far'm, Canada Department of
Agl'ieultUl'e, Ste. Anlle-de-la-Poeatiere, Quebec.
1. .T. Elling, Department of Agronomy and Plant Genetics, University
of :Minnesota, St. Paul.
A. W. Hovin, Crops Reseal'{'h Division, Agricultural Research Service:
formed}" es. Regional Pastl1l'e Research Laboratory, University
Park, Pa.; now, Plant Industl'y Station, Beltsville, .Md.
H. ~\foller Xielsen, Department of Plant CultUl'e, Royal Veterinary
and Agricultural College, Copenhagen, Denmark.
E. L. Sorensen, Crops Research Division, Agl'icultural Research
Service, at I\:ansas Agri{'ultUl'al Experiment Station, Manhattan.
E. H. Stanford, Agronomy Department, University of California,
Davis.
G. A. Stringham, Department of Agronomy and Plant Geneti{'s,
Cniversity of :Minnesota, St. Pau!.
W. ,J. Whittington, S{'hool of Agriculture, University of Nottingham,
Loughborough, England.
C. P. Wilsie, Agronomy Department, Iowa State University, Ames.
II
CONTENTS
Including Traits and Gene Symbols
Page
Introduction ••. _____ • _'_" -._ -- - •• -- ---- - .-. --.--- ----------------- --
Gene
Disomit:.
inheritance
symbol.~ I
Tetrasomic inherill.lfLce aifalfll (2;'\ = a2) •••••••• _•••••• , •• _. ____ • ____ - __ - - - ______ --._
Hypneo(yl and mot trait;; .. _._ •..• _•• _. -- ____ •. -- __ .._. _____________ _
l'.lon!!;uted hypoeot yL .• _... _' _. ___ ....
el
Red rooL _., .... _. ___ •• , ___ ..... ___ ..
Rei
\tou!!;h rooL ____ -....... _. ___ .•. _.....
.-._
---Leaf nnd stern trnii>;_ •.• _____ . __ ••.•• _•.• _.• _.. ________ • ___________ ._
Crinkled leaL •.•..• ____ ., _..... _. _'" eI, 1', and ('r
Dwarfncss ..•. _.• _.. _.......... _•• __ . rill'
Dwarfness! __ • ________ . ___ - ____ • _- ---.
clIV,
liw,
Dwarfncss2 ... __ •.•. _" •• -_ •• -. -- -.-.
Folded leaf. __ ...... __ . ___ ._. _______ •
fa
;',[ott/ed leuf. ____ • __ •• _. __ -_.,. --. -. -.
mq
~I\lltiple cotyledons.... _______ - -. _ - - -­
~I\lltif()li()lat(; leuvc!'- ..... _. • __ •. _. __ •
Pale-!!;reen plant rolor. . ••••. - ..• __ .
'P!I
!'It
Ruptured epidermis ...•.•.•.• _....... .
Lt' Ilnd Le.
Seedling leth/d . . . . _•• _•..•• _........ ..
Stern (·olor •...•....• - - ....... __ ._ ..
Htieky leuf .... _, _ . ___ •. ____ ._ -_ •. _._.
Two nnifoliolale leaves __ .... _••. _____ _
Viridis Icaf color • ____ .. _' - ." - - - ._ - ••..
I',
Y('lloII'leaf_.. "_."" ____ ... __ • __ •
X,
Ycllow colyled"lIs~ ... _. ___ •• _._
x~
Yt'llow ('otylt·don:;~ .. _____ ... __ • _
x.
Yellnw cotyledons, .. _... _. ____ . ___ ....
x,
Yellow ('otyledons6 _." __ • __ • '" .... _
x.
J-t'iJra lenr. _. _.. __ . " .. _' • ____ • _" _....
zc
Flower Ilnd seed traitll ...• , _. _. _... . - _. _- ... ___ - - --- ••• -- •• - ------ --Branehed rlll'emc . • _ • __ ..... • . ____ HI! and Rot
11, Br, and
'!\~traploid
br!
Exposed stigma •.• _•• ___ . ___________ •. cs
Flower ('olor __ ,._._ -._ ••. --.- •.. -- ___ • __ •• __ ... ___ •• _______ • __ -_.
Purple _____ . ________ ,, __ ._ ..... _
p
Yellow . . . . _.. ___ . __ ......... ____ •
l',llnd Y.
VllriC!!;llled. ______ •• __ - ___ ., - _- - - - .\\'hilc ___ ._ • __ •• _______ . _______ ._.
c
C'renm _... __ . -. _. _- __ - - - • - - - - - . - - - - .
Hornless winl-( pet.llI,, __ • ____ ._ ...... _..
hi
.\lale sterilil\" (anther nondl'hisceo('(·) .. _ /II.<! Ilnd III.~.
.\ll\le sterilitj- (pollen-I-(rain degencmtion).
Open keeL_ .• ____ ._-_. ___ • ____ ....... -.
Pod IIILirill(!i\s_ ........ __ ........... __ .
(/ and I
Beed color. ____ .•.. __ ••. -----.". - .... --.------------ -'--'-"---"
B1ack__ ••• ______ • _____ ._ ........ __ • Y, (\, C" B
\rhite_ ......... ___ ._ ... _____ ._____
c
V('stip;hl (·orolln ___ ••••• _.. ___ .... _....
I!C
Vesli~lll\ tlower •• __ •• ______ • _. _______ •
F Jlnd F'
D Ilnd l'
/II",
III
1
1
1
2
2
:J
3
3
3
a
:3
4
5
5
7
8
8
9
11
11
11
11
15
15
15
15
15
Hi
16
17
18
l!)
19
20
20
20
20
20
22
22
22
2:1
24
24
25
25
Trail$
Gene symbols
Disomic
Tetrasomic
inheritance
inheritance
Tetraploid alfalfa (2N =32)-Continued
Plant resistance__ ------ ----.-- - - - ___ _ _ _ _ __ _ ____ __ _ _ __ ___ _________ __ _
Downy mildew resistance_ - - - - -- ______ .
Dm
Pea aphid resistance ___________________ Pa and]IT
Root-knot nematode resistance__________
Rkl and Rk.
Stem nembtode resistance______________
Sn
Diploid alfalfa (2:\ = 16) - - ---- -- - - --- -- -___ _ _ __ __ __ ___ _ ___ _ __ _ ___ __ ___ _
Leaf and stem traits______________________ __________________________
Cotyledon chlorosis____________________ gc arId Yc
Crinkled leaL ________________________ el and Crl
Lute.scent (;otyll!uons __________________ Lei and Lc.
Multifoliolate leaves___________________
mf
Flower I\nd seed traits ___ -- - -- - - - -- ___ __ ___ ___ ___ _ _ ____ __ ____ __ __ ___ __
Calyx pigmentation_ - - _ _______________
Cp
____
Fl0wer color-- - ----- - - -- - - - -. - -- - -____ ___ ___ _ __ _ ___ _ _ ___ __ __ __ ___ _
Purple_ ----- - - - -- - - -- --- --- - - -_ _ _ __
P
Yellow (xanthophyll) ________________ 1'XI and Yx.
Yellow (pigment unknown) ___________ Y, and Y,
Variegated_ - - - - - - -- -- ---- -__ ___ ____
Cream __ -- - - - - -- - ---- - -- ____ ____ _ __
White_ - - - -----------______ ________
c
Modifying pigments. ________________ K. and K,
Male sterility (pollen-grain degeneration)_
ms,
Ovule Ilumber ________________________ QVI, Qv., Qt",
and Ou,
Purple bud color ______________________ Bs and Bf
Vein color of standard petal. ___________ Vs I and l's.
References___________________________________________________________
Washington, D.C.
PRIt'! 26 26 26 26 27 28 28 28 30 30 31 32 32 33 33 33 33 33 33 33 33 33 34 35 36 37 Issued March 1967
AN ILLUSTRATED SUMMARY OF GENETIC TRAITS IN TETRAPLOID AND DIPLOID ALFALFA H.~NSON, research agronomist,
Crops Research Division, Agricultural Research Service
l3y D. K. IhnNEs, research gendicisl, and C. H.
INTRODUCTION
Simply inherited markers in alfalfa are urgently needed for research on
genetics, hreedinp;, and seed production, especially for studies dentin!!;
with heterosis, genetic shifts, and habits of pollinators. This publication
('om piles published and unpublished information on genetic markers
studied in the M cdicago saliva L. species complex i:, a summary form and
makes sueh information more accessible. The compilation is limited
largely to traitH for which a factorial hypothesis of inheritance has been
proposed. Some of the traits arc more useful as markers than others.
Information presented on each trait consists principally of a description
and a brief ac('ount of its mode of inheritance. Whenever possible, black
and white photographs are used for illw;.tration. Inasmuch as some ex­
prebsions are best shown in color, the number that can be effectively
illustrated here is limited.
Genetic symbols and nomenclature are in accordance with usage
rerommended by the Alfalfa Improvement Conference. In some in­
stanees symbols were changed, but only with the concurrence of the
originating author.
TETRAPLOID ALFALFA (2N
=
32)
Hypocotyl and Root Traits
Elongatecl Hypocotyl
Davis (21) 1 reported that elongated hypocotyl (fig. 1) was conditioned
hy a reeessive gene inherited in a tetrasomic manner. He noted a defi­
(·iel1(,y in the recessive class, which he attributed to differential gametic
viability. He proposed the !!;ene symbol cl. The original mutant was
found in an St family and was partly ehlorophyll deficient. However, it
had sufficient chlorophyll to produce a normal-sized mature plant.
Chlorophyll defieiency and elongated hypocotyl appeared to be condi­
t ioned by the same recessive gene in the nulliplex condition, but a hypoth­
esis of closely linked genes could not be ruled out by the author.
t I lillie numbers in parentltef,es refer to References, p.:37.
lished master's and doctors' theses have also been included.
References to unpub­
1
2
'l'ECHNICAL BULLETIN NO. 13iO, U.S. Dl!}p'r. O}l' AGRICULTURE
-,
i
*\I
B I
(
I
/
-t
\
1.-..1, Seedlings with ~Iongllted hypnrotyls; fl, seedlings with hypo('otyls of
normal length. (C(ll1rtes~' Agronomy Department, Purdue l'niYcrslty.)
FIOPII!::
Reel Root
Red root, caused by a red pi~n1('nt in the root cortex, is not <-Iearly
differentiated until seedlin),!:f> are 1) to 6 weeks old. YOlln.!!:el· fieedlings can
bc acC'uratc1y das"ifi('d if the r('d pigment is intensified by dipping roots
into concentrated hydrochloric acid. The o('('urrcnce of red root mutants
in alfalfa was kno\\:n neady 20 years before the inheritan('e of the trait
was studied by StanfonJ.2 He ('oll{'\uded that red root \\I1S !'ollditioned
by a single dominant ~enc Nfl with tetra:.;omi(' inheritanee. He foulld no
indication of either zyp:oti(' or j.!amcti(' inviability asso('iated with the red
root allele. Barnes and (,lc\'Cland (·n, howe"cr, observed a defieieney of
red root segregate:.; when the Rd allele \\'a:.; transmitted through the
pollen. Transmission through the seed parent appeared normal.
Rough Root
A heritable rough root trait, superficially similar to a ('ondition arising
from winter injury, was deseribed by.Tones (27). The rou~hness origi­
nated from an abnormal periderm. The phello~en of rou~h root plants
develnped deeper in the root cortex than in normal plants, and remained
continuously ac,tivc, but the thiekened phellem pl'Odu{'ed did not appeal' to
protect underlying ('clls. ::;llhsequently, a new eambial a!·tivity was in­
cited, which usually failed. l\lost plants with this trait did 1I0t transplant
well. Tn the study desl'l'ibed by .Jolles, ali S, progenies from rough root
2 S'l'ANFOIW,
E. If.
Octobcr 30, 19til.
[Personal corrcspondencc.l
GENETIC TRAITS IN TETRAPLOID AND DIPLOID ALFALFA
3
plants had abnormal root:" but the degree of roughness often varied
among plants. All plants with rough roots, however, could be identified.
Crosse,s between rough root and normal plants produced FI plants with
normal roots. From 2 tt) 20 pereent of the individuals in three F2
populations of about 50 plants had rough roots. A genetic hypothesis
was not presented.
Leaf and Stem Traits
Crinkled Leaf
Odland and Lepper (37) deseribed a plant with crinkled leaves, which
was observed in the progeny of a cross between tetraploid .lIedicago sativa
and tetraploid .1/. fa/c(lia L. TIH'Y l1!'('I'ibed the abnormality to the
epidermis and mesophyll growing at a more rapid ratIO t,han the vascular
tissue. The degree of leaf erinkling varied among plants. A large amount
of erinkling was detrimental to the plant and i'esulted in stunting and
restricted flower produc,tion. On the basis of F2 and limited Fa data, they
eonduded that two eomplemcntary dominant fattors D and E were pres­
ent in normal plant;;. Absellec of either of the two dominant factors
produced the erinkled trait. A third faetor, dominant Cr, also produeed
erinkled plants, but only when faetors D and E were recessive. Disomic
inhel'itanee was proposed for the three faetors, but the possibility of
tetrasomie inheritan('e was not investigated.
A phenotypieally similar trait (fi!!. 2) was studied in advanced genera­
tions of a ('ross brtwcen diploid J/. salil'a and diploid Jf. fa/cala. (See
Crinkled Leaf, p.:30.)
Dwarfness
Pauli and Sorensen (42) desc'I'ibed a dwarf mutant charaeterized hy
greatly shortened internodes and a den;;e rosette of small leaves close to
the ground (fig. 3). Dwarf plants failed to develop floral primordia under
eonditions that resulted in profuse flowering of normal plants. Flowering
and seed set developed only after applieations of gibberellic acid to soil in
which the dwarfs werr growing. Sorensen 3 found that dwarfness was·
conditioned by a recessive genE' dw and expressed in the nul1iplex condi­
tion. He postulated a tetrasomic mode of inheritance.
BWlbice (13) reported finding two additional dwarf mutants with
phenotypes similar to the dw dwarf described by Pauli and Sorensen.
Dwarfness in each ease was ('ontrolled by a single recessive gene with
tetrasomic inheritance. IntereJ'osses between the two dwarf mutants
produeed normal I<\ progenies. Busbice, therefore, concluded that they
were controlled by diffcrrnt genes, which he designated dWI and dW2.
No information is available on the possible relationship of the dw gene
to either the dWI or the dW2 gene.
Folded Loaf
Schrock (48) and Stanford and Clevrland (52) described similar folded
leaf mutants. Leaflets showing the trait are folded toward the adaxial
:J SORENSEN,
E. L.
December 11, 1962.
[Personal correspondence.]
4
TECHNICAL BULLETIN NO. 1370, r.S. DEP'l'. OF AGRICULTURE
FIGUltg
2.-Crinkled leaf trait.
side of the leaflet along the midrib (fig. 4). The two halves of the leaflet
may adhere along their entire length 01' only at the apex. EXp1'cssion of
the trait, aC'eorcling to Stanford and Cleveland, is variabie, with some
plants having neariy 100 percent folded leaflets and others having only 25
pert'ent. The fold('d leaf trait is expressed in the unifoliolate leaf, but
trifoliolate leases an' mol'(' a('C'mately eia:o;sifipd. Rtanford alld Cleveland
showed that the folu('d leaf trait was ('onditioned by a single recessive gene
inherited in a tetrasomi(' manner and proposed the symbol fa. A defi­
eient'y of reeessive types was notpd in simplex and duplex families.
Sehroek repOltE'd that his fold('d leaf mutant was eonditioned by a
dominant gene. However, he studied only one segregating generation so
it was not pflssib]e to difTerentiate disomie from tetrasomic inheritance.
Mottlea Leaf
Stanford and Cleveland (/i2) dps(,l'il)('d a leaf mottling that was charae­
terized by a ('hlorotie condition of the leaf sUl'faee, interspersed with
f1ec:ks of green (fig. 5). OC'netil' studies showed that mottled leaf was
determined by a single reeessive gC'lH' that was inherited tetrasomieally.
The gene symbol mo was proposed. All mottled plants had some normal
green sectors and some had one 01' more normal shoots. These green
GI~Xg'l'I(' TltAIT~ lX Tl':'I'ltAI'LOID AXD DII'LOlD ALFA"U'A
FJ<WHJo: :1.
5
,1, rill' dwnrf spptiling: 0, normal HP('(lIing.
~('dor~
and /.!:1'(,(,11 ~h()ot~ WPI'e' shown to 1)(' tilt' rrsult of a hil!:h Illlltation
!'atl' of tl)(, UW l!:('!ll' and Ilot of n vtll'ial>ll' ('xpr(':-.~jon of till' trnil. ,\T 1I1n­
t i!lll~ llppparl'd t () (I('('UI' fmlll mottled (1) IIOl'llutl. I{p\'prsp lllutatiolls \\'('1'('
not o\JS('l'\'p(L
Multiple Cotyledons
III a (loplIlat ion of [S,S·\;) ~('pdlill.!!;~
rl'Olll alfalrn
\'a.ripti('~ Rall),!;!'1'
and
\'PI'nal ttt ~l. Ptwl. :\Iinn.• \), I~. Bal'lH's and L. ,J. 1~llinp; (data unpuh­
!i~ll<'d) ob"I'l'\'('d that O'(i \ P('I'('Pllt or til!' plallh had tl\l'('(' (,()tyl('don;; nlld
appr()Xinllltr'\Y (l,O!i ))['('('('lIt had f()lll' (,[)tyl('d(lll~ (Ii),!;, (il. 11l\»)'('('dill).!: or
plants with Jllultip\1' ('()lyblnl1~ for thn'(' to fl\,(' p;PIl('l'atioIlH in('I'(,:1:-;I'\I til('
fII'CLtI<'fH'.\' of 1IllrltiplC' ('olylC'ciop-; frolll I,tl P('I'('('nt to as hip;h as SH.O pC'l'­
"(,lit ill ~(,\'pmllill\'~, III addition. a rpII' planl,; with [i\'p and "ix ('otyl('­
dom; W('I'(, oiJspl'\'PtL ::-)('\[illl!: plants with (il'(' und Hix ('otylrdol1R inl'ul'i­
6
TECHNICAL BULU:TIX XO. laio, c'.s. DI~PT. eli<' AGRICUUrUHE
FWUHE
'i.-Folded leaf trait.
FIGnn: 5.-:\Iottlcd leaf trait.
('ourtl'RY Agronomy Dep:irtment, l'niversity of California.) (C'ourt('H\" Agronomy Department, Cniversity of
California.)
.
GENETIC TRAITS IN 1'ETRAPLOID AND DIPLOID ALFALFA
7
ably produccd progcnil's with hi/l;hcr frequeneics of multiple C'otyledons
than were obtaincd from flclfing plants with four cotylcdons. Likewise,
plants with thrct' and four eotylcdons produecd a hi/l;hcr frequency of
plants with multiple ('otylt'dons than did plants with two and three
eotyledons, rcspl,('tiyt'ly. Howcvt'r, no plants wcrc fOllnd that were
homozygous for multiplt' eotylt'dons. Discussions with othcrs working on
this trait inc\ieatc that plants homozygous for multiple cotyledons have
not bt'cn isolated.
Barnes and It. W. (,I('wlant! (data unpllblisll(~d) at Lniversity Park,
Pa., found that (·otylC'c\on chlorosis appcarec\ to be associated with multi­
pIC' ('otylt'dolls in diploid alfalfa. Bal'llt's and Elling (data unpublished)
at st. Paul, Minn., found that l'otyledon ehlorosis also appeared to be
a~~()('i[Ltl\d with multiple ('otyl('d()n~ in ~(\v{'ml lim's of t{'tl'llploid alfalfa.
Pale-Green Plant Color
BarnC's and Ho"in ('f) studiC'c\ a mutant with pale-grcen stems and
lC'a\'('s (fig. 7). ('Iwmieal ltnalysC's of mutant plants inclieatec\ they had an
in('rC'aH{,c\ ratio of (·hlorophyll (L to (:hlorophyll II and were about 70-percent
ddi('iC'nt in total ('hlol'ophyll. HC't'dling viability appeared normal when
('\assifiC'd at 2 or :3 wC'C'ks aftC'r pmergell('c. Mature pale-green mutants
pl'Odtw('(1 f1ow('rs and ~('(\d hut often HowC'red sl'"C'ral wecks latcr than
nOI'l1Htl sihlings. Pall'-gr('('n plant ('(lIm W[L~ inherited tetrnsomieally and
('()nditioned hy UH' lIu\lip\(';.: ('onditiol1 of the pg genc. This mutant
('an 1w phC'l\otypi('ally diITerC'ntintC'd frolll the viridis leaf color mutant
dl';.wrihed hy ('hildprs anel :\ It- Lennan (17) 1)('('auHe the len,vps and stcms
Hn: uniform in ('0101' llnd have no whitc leat blades or dark-green leuf
velIlS.
1"J[1t'f(~, 6.-A, Chlorotie seedling ~aving three ('otyle(\ons; B, normal green seedling
hnvmg four cotyledons.
S
'I'I';(,II\'I('AL llrLLETL\'
Ffl,I'HI';
i.
~O,
1:l;"O, L;-;, DEI'T,
..I, I'lanl hal'llI)!; pall'-)!;f('PIl plant
('01,,1':
()lo'
AWU(TL'ITHE
II, plant h:l\'jn~ [lormal rolor,
Ruptured Epidermis
\rhittinglon and Hlln'agp l:i(;1 d(':-;('I'iil('d th(' I'uptlll'pd ('pidl'l'l11i~ tmit
n.. . V-"IHql!'d Illal'kill!.!;:' Oil. t hp laillina (fig, Xl. Thl' V-Ill:Ll'kl'd ltl'l'as
W(>I'(' ligld gl'PPll, whi('h I'l'sttltpd fl'olll tht' I'llpl.lIl'(' or thl' Ipaf ppi(iPl'Il1is
dlll'illg ('xpall:,ioll. 'I'll(' ratp or I'('''piratioll of thl' l'fltil'(, Ipllf \\'us not duly
aff('('\('d hy til(' Illal'king:' and l1Iutant plallts \\'PI'P flot lloti('('alJly \\'pak('l',
[t WlIs PI'Ol)(ISt'd Ihllt til!' /lllllaill trait was ('xpl'(':,:,('d \\'h{,11 two 01' 11101'{'
J'('['(',,:,h'p alll'If':' of 11](, l<'tra:'ollli['ally illh('I'it('d I'll gl'lIl' \1'('11' (H'PSl'llt, TIl('
:tilthOJ'" 01 '';f'I'I'l'd , lul\l'p\'!'I', that t hI' llllltalit gl'IIP apPl'tln'd to \'al'y in
pPlidrallf'(' alld PXIII'C':,,,h'ily,
Seedling Lethal
Lp\\'i:, and Elling (..I} I I'Ppol'!!'d ]dlml i!l'IH'S ass()['in.trd wit.h thf' drath of
,,('('dling:' ·1 to I~ \\'('f'I\." old nt tlw thl'('p- to fOlll'-l('af stagp, \\'11('11 the
"pc'dlill.!.!:'; \\"PI'(' ,,('\'pmlw('t'ks old. th!' III'\\' Ip[lI'PS \\'('1'(' smalll'l' than no!'mal,
awl li.gilt('f" ill ['0101', and had It rnld('d ap(l('anllll'p !fig,!)). Ikfoliatioll
(J('('I1I'!,pd gradllally. I)('gililling with til(' low!'!' Ipaws, :-;tPIl1S \\'('1'(' spilldly
and roots wpn' Ilildpl'ti('\'('lop('d, TiI(' (mit apP('ill'l'd to il(' ('olltroll('d ily
two ('olllplC'mPlltaI'Y .gPIl('S 1,(, alld IA'~, hut 1Ill' data \\'('1'(' not suffi('i('Jlt
to dilTpf'pnli:ttl' dis()l1li[' frolll tl'tra:<olllic' inIH'I'ital)(,(', 110\\'(' \'P 1', latp!,
"twlic's hy ~t l'inglutlll find 1':llin.g· inrli('at('d that. tlip two P;<'Ill'S \\'(,I'e
lIt111't'it[·" ill a t!'\I':l~(IIlIW IllalllH'l', I'lalll,.; of thl' 1.(' - - - /1'2 /('2 /('2 /1'2.
Ith Il'il' I.{'~ - - -. :llIIllrll'iI'/t' fr·! /1'2 /('~ It~, .!.!;l'II[)ty(H'S \\'('n' IIlll'f)wl; plants of
till' 1.(' - - - 1.1, - - - gl'lItltY(I('''; dic'd,
I :'nt"I,ll \\1, (; . .\ ..
L"atiOCl.;
and
I-:r.I.f\C;,
L. ,I.
.\lnn'lt IB, Hlli;i.
[I'('rs()nal
('lllllllllllli­
GEXETIC THAITS IX TETHAPLOID AXD DIPLOID ALFALFA
FII,nn:
S,'-
9
·]'paf ~h,,\\'ing f'haraf'lp[,j:<tic' han ing of ruptured ppidprmis trait. (Collr­
'",1 Illlgham. Loughborllllgh, Ellglancl.)
Ip~,\' ;'1'11",,\ "f ,\gri"nlt\lr('. l'lli\'l'r"il,\' "f
Stem Color
:'t[any workPl''- haw oll:,('!'ypd alfalfa plants with !'x('ppcling]~' )'cd stems.
ar!' p"pr't'jally ('oll"pi{,1I01lS in till' alfalfa ya)'i('t~· :'[oapa.
'\"('ording to :-\('lIal' 111(')' ! ;71 awl to 1\(ll'Oiloua \,)/ I a" (·itcd by Atwood and
!{('(] ~t(,Il\"
10
TECHNICAL BULLETIN NO. 1370. U.S. DEPT. OF AGRICULTURE
'II::.~!
'5.~-. ..r
9.-...1 and C, Seedlings showing spindly stem and underdeveloped root
characteristics of seedling lethal trait; B, normal seedling of same age. (Courtesy
Department of Agronomy and Plant Genetics, University of Minnesota.)
FIGURE
GENETIC TRAITS IN TETRAPLOID AND DIPLOID ALFALFA
11
Grun (2), crosses between red- and gree'1-stemmed plants indicated that
~reen was dominant over red. However, expression of red was often
vaJ·jable. Neither worker presented eonclusive evidence ao;; to genetic
control. Expression of red stem color appears to be similar to that of most
plant anthocyanins jn that the degree of pigmentation is influenced by
environment.
Sticky Leal
Stanford (.50) described a sticky leaf abnormality that was character­
ized by adhesion of adaxial sides of adjacent leaflets, as well as adhe"ion of
opposite halves of the same leaflet (fig. 10). The trait can be identified in
the three-leaf seedlill~ stage. Stieky leaf plants are fertile. Stanford (51)
indieated that the expression of sticky leaf was controlled by one gene with
tetraljomjc inheritance and was expressed only in the nulliiJlex condition.
The symbol st was proposed.
Two Unifolio/ate Leaves
The normal developmental sequence of an alfalfa seedling includes a
pair of cotyledons, a single unifoliolate leaf, and trifoliolate leaves. Perga­
ment (44) described alfalfa seedlin~s with two individual unifoliolate
leaves instead of one. Preliminary data indicated that this trait (two uni­
foliolate leaves) was eonditioned by one recessive gene inherited ill a
tetrasomic manner. Later work by Davis," however, indicated that
se~regation ratios may fit either a Letrasomic-disomic or a strictly tetra­
somic type of .inheritance.
Viriais Leal Color
Childers and 2'-lc Lenllan (17) liLated that this chlorophyll mutant lacked
plastids in the leaf blade, although some plastids oceurred in the mesophyll
tissue nround the midrib. Low and intermediate chlorophyll-producing
elasses of se!l;regates could not be distinguished in the seedling stage, but
elasses could be differentiated when plants matured (fig. 11). In the low
ehlorophyll-producin,!.!; claSt), petioles and veins were green and leaf blades
were white. In the intermediate dass, petioles and veins were green,
but leaf blades were pale yellow green. The authors concluded that inher­
itance could be dc;:;cribed on the basis of a sing'le recessive gene inherited
tetrasomically. They proposed the symbol VI. This trait is phenotypi­
cally different from the mottled leaf trait reported by Stanford and Cleve­
land (52).
Yellow Leal
According to Childers (J 5), this mutant has yellow cotyledons (fig. 12)
and leaves. A few seedlings lived to maturity but were dwarfs. Leaf
5 DAVIS,
R. L.
Xovember 30,1962.
[Personal correspondence.]
12
TECHNICAL BULLETIN NO. 1370, U.S. DEP'r. OF AGRICULTURE
'.
•
.
'~'.'
"
"
t
'-~
'L ~.-.'
~-,,~
·f·"
'/,~"
if·
Y
,.
•
."
i
~ l.~
FIGURE
IO.-Sticky leaf trait.
.;~
(Courtesy Agronomy Department, University of, California.) i1
.,!'t1'~
• :"j>-
t',1·',·
.1,.
• ~,"r
l ···,~'\,1. ~ '~~·.~r.,
't·,_t,,'-..,
1.... 1\1·.... ... L,n.\:u!!
,·h~'lr,.j;r~
' • • ,!!~i ..... ;tJ·i·lq'lrtr:tJt
i \.~lt·:a!.Lt r~·.~i
1
trIH
('all~ld,l
Ipai l,ladt'....
~r£>pJ1
JIPlifllp ... .
"il(oIH!r{jI,Jj.llrnlalhl;l\·t~ ... .
I h·p.u·tnu·uf
qf .\grH'uhur(1.
II
TE(,IIX W.\'L lll"LLETIX X(). 1;;;-0, (',S, D]':I'T. OF A(;l{l(TL'ITHE
[.'11 Wltr: 12, ;':ppdJing~ ,pgrpga' Ill!! fllr lIormal gr('pn rll, \ lI'don" anrl ypllol\' ('()(.I'lcdn[]I'.
TIll' \an,'r al'p t ,.\'1<':<1 "I' ,Ill' plll'll" , YI'P pxpn",p,II,,' any IIf I Ill' .r" .r" .r" .r" :lnd, .r.
gf'IlI'", -('''Ill'!!''1 ['t'lIlrnll';\IH'rlIlH'nl:d Jo'arlll, ('HII:ul:ll)ppartllH'llt IIf A,griellltllrp,
'lttawll, ()nlan... ·
llllltallt pl:lnt-- \q\:< ,.illlilnr to thnt of normal ~r('('n
IJl1t pln'tid" (ook lip ,.taill \I('akh' ill ('ompari"ol\ witil pla:-;tid:-; of
llnrlllnl\p:LYI',., TIt(, tntit \\'a" \'ondit iotH'd hy It "il\\!;k \'('{'('""iy(' g;(,IH' with
tplra,ollti,' inlwritalll'('. 'I'll(' !!PllI' \ras dpsiilltlt(,d xtllltllll-l alld a""i!!;nNi
\Ilf' ,ynll,ol.l',. ('hildl'I''; poill\!',i ollt t Ill' similarity of thi" l\\\lt:\I\\ to til('
tj""1H' ,.trw'lmp flf
\(,H\P",
GENETIC TRAITS IN TE1'RAPLOID AlI."D DIPLOID ALFALFA
15
lethal yellow leaf seedlin)!; trait repOl·ted by Kirk (301, which the latter
interpreted as controlled by two 01' more rece5sive p;enes with disomic
inheritance.. Childers reeakulated l-\:irk's data and found that they sup­
ported his hypothesis of one recessive gene inherited tetrasomically.
Yellow Cotyledons
DeSSllreaux (22) reported foul' genes associated with yellow cotyledons
in alfalfa. Seedlini!:-i with yello\\' ('otyledon:-i usually died before the uni­
foliolate leaf appeared. All foUl' )!;ene,.; were asso('iated with similar pheno­
types and were inherited in a tetrasomic manner. The nulliplex condition
of each g"ne produced yellow ('otyledons. Phenotypes of the p;enes were
similal' to the xantha-l gene des('ribed by Childers (J 5). Therefore,
DessUl'eaux desi/l:nated the foUl' )!;enes xantha-2, -6, -4, and -5 with gene
symbols X2, .C;!, .['4. and .r5, respeetively. Available evidence su)!;gested a
linkage between the .r2 and .ra genes.
Zebra
Lea'
A('('ording to Stanford (,;0), this ahnormalleaf trait was eharacterized
by a ('hlorotic strippin/l: of the leaf, runnin~ at right angles to the midrib
(fig. 13). It was readily identified under all environmental conditions, but
•
FWl'RE
13.-Zebra leaf trait.
(Courtesy Agronomy Department, Univer~ity of California. ) l{')
TE('jj:\}(':\L Bt'LLETI:\ :\0, l:r;-O. L:-\, f)l~P'l', (H' AUHICrL'lTRE
Wl1!' moJ'(' ol)\'io\I:' at lo\\' tplllll(\mhu'l':' \\"11(>11 tit!' t'lIloroth· al'('[1:, \\'('1'(' more
::hnrply lit lillpd. Till' (Ipman'ation:, \\'('rp Ip:,,, pl'onouIH,(·d at !'ummel'
tl'lllppratllJ(':: but ('oltld h(' idl'lttifi('d,
Zphra plnnt:: WPI'l' noti('Nlbly
w('akpl' al1d <lil1'(,I'('d illvial,ility, ,\ ::illglp t£'tra"'oll1i('ally inhpritt'd I!;('nc,
(l('"i!.(lHll(·d'::l hy ~tallford, (oll\l'Il11c·.l tltp iwlll'a 1mi' trait. TIll'lIu\lipl('x
alld ~jlll(llpX ~('not,\'pl':: ('xpn':::,('d till' lIIutant plH'llot,\'pe, ()Oll1illlllH'P of
thp !tol'lIml phpllotY(l<' \l'a" ('xpl'(',,:,('d at til(' dupll'x 1('\'p1. '1'1)(' )!;PIlP iJ!'­
ha\'('d primmil." a . . a r('c'p""i\'(' ('XI'ppt for thp lllutant ('xpn',;,;ioll of the
,.irnpl('x j!;l'llotyp(',
Flower and Seed Traits
Branched Raceme
Th(' brmwl)('cl mC'PIll!' trait wa:; fir:,t Ilotl'd In' \rl':;tgatp (:,:)!. Latr'r
Dudll'yalld \\,il:,j(' il,i, .11 i dl':,c'rill('d a mutallt i)iant tlint hor(' profll,;{'ly
brallt'iIPd pallil'l('-likp intlore';('PlU'PS instC'ad of normal l'tlN'lHC':\, but had
Fu;nn; I·!.·· ·,·1, llranC'lH'd nl('(,II1(' IW\'ing; vpsl i/!;ial no\\,prs; 1/, r:l('PIllP;; havirw; normal
f1u\\,prH, I ('(Jllrll'''Y A/!;ronorny J)ppaJ'i JIll'JlI , lo\\'a t-itnlp l'niver~ily,)
GENETIC TRAITS IN TETRAPLOID Ai':D DIPLOID ALFALFA
primarily all vestigial floral parts (fig. 14).
17
They pl'Oposed symbols A,
Br, Ra, and Ra' for genes ('ontrollill!J; inheritanCE of branched raceme.
O('n('s 11 and Br were assumed to be illiJp.rited in a tetrasomic manner with
random chromosome segre!J;ation; Ra and Rat were postulated as duplicate
disomic genes. Some interaction;; among !J;('I\eS were observed. Branched
raceme and vestigial flower were related genetieally, but the basis for this
relationship eould not he determined.
Childers 6 dis('overrd a plant with branched racemes and normal floral
parts among 8 1 prog('nies of a plant tracing to the alfalfa variety Fla­
mande. Nonr:1.11v the pedicels of a raeeme produee one floret, but the
redieels of the branched rae('me trait !J;l'ew much longer than normal and
l'ac:h produced a clu~ter of from thr('c to seven florets (fig. 15). As many
a1': U 9 florets were observed on a single branehed raceme at Ottawa,
Canada. l~lant growth type was normal until the atypieal flower traits
developed. In the !J;reenhouse, some florets aborted, but seed production
generally was normal. When the branehed raceme mutant was crossed
with n nOlTl,:.t! plant, all FI plants hnd normal raeeme:;. F2 segregation
inciirated genctie l'ontrol by II single rree:;siv(' gene (brl) inherited in a
tetrasomic manner.
Exposed Stigma
According to Markm; and Wilsie (S,5) , this floral abnormality is charac­
t('rized by {'omplete exposure of th(' stigma, which is first observt:hle in
the late bud sta!!,e (fig. 16). Petal size is reduced and the keel never
completely encloses the srxual ('o[ullin. The style appears normal in
length, the filaments appear short, and the anthers shrivelled and non­
dehis('ent. Pollen p;ntins are few and stieky, but appear normal ill aceto­
('armine smeal·S. In the greenhollse the clone was male sterile but
('ompletely femal~ fertile. rnder field conditions it did not set seed,
apparently becau!:'c it was unattra(,tive to pollinating insects. The
authors postulated a single reeessive geM es inherited in a tetrasomic
A
FH:cm: 15.-A, )lormal raceme; B, branched meeme in bud stage; C, brunched
mceme in full bloom. (Courtesy Central Experimental Farm, Canad!l Department
of Agriculture, Ottawa, Ontario.)
6 CIIILDEIIS,
W. R.
February L3, L964.
[Personal correspondence. I
18
TECH~ICAL BI-LLETIN NO. l:r,O, LS. DEPT. OF AGR1CULTTIRE
A
B
15.-A, Rll{'erne with normal f1()ret~; B, rllcenl(' with florets huving exposed
lC'ourll';;Y Agronomy Department, rowa Stllte
L'niV('rsity.)
FlGl"IlE
~Iigrnas charar\l'ristil' (If /'.' gene.
mann(>r. The d(>xignation a wax u~ed in the original publication but was
not int(>ncieci a" a g(>neti(' symbol. The symbol es waR suggested by
\yil~i('.7 Th(> (>xpo::ed :-:tigI1la wa:-; expressed by the llulliplex C'ondition.
('onsi:-;tent defieie Ilciex of th(> Ilulliplex genotype sUI!;/!:ested partial selec­
tion against r(>('('ssiv(' gamet(>s .
.:\ similar kind of (>xpos(>ci stigma was d(>scribed by Xielsen (36). It was
characteriz(>d hy the stigma and anthers I!;rowing through the tip of the
k(>ei petal (fi!J;. Ii). The "tr(>ss on the staminal eolumn waS less, so that
('haraetNistie bending to about 90 degrees, whieh takes place after
trippin!J; in normal 110wrrs, failed to ocelli". Thus, the staminal column of
the abnormal f!o\\"(>rs was :;traight, and aftN tripping turned slowly to­
ward the standard. Expresxioll of the exposeci stigma tmit was greatest
whrll the air was relati\'elv warm and dry, and least when the air' was ('old
and humid. Flower's with rxposed stigma ("ould be pollinated by bees
without trippinf.!. \\'hell tripping o('('urTN!, the bees did not receive the
hard hlow from the stamitJai column u>iually experienced from trippin)!;
normal flower;;. Preliminary stucliE's indicated that the exposed f:ti:!;ll1a
trait waR heritable but ('omplex, bemuse expression of the trait was
variahie and greatly affected by environmental conditions.
Flower Color
::.rorc than 20 Rtuclies of flow(>r color inheritanec in tetraploid alfalfa
have bcen puhlished. Information from them and from studies that have
not been published was summarizcd and reevaluated by Bames (8). A
,summary follo\\'s but for sake of brevity. the original referenees are not
cited.
1 WILsn;, C. P.
Xo\'emlwr 27, 1062.
lPcrsonn! correspondence. I
',Llll
11:.\11 .... 1\ II :1:\!'UIIll \\). !Ji!'UllJI .\I.I.\I.F.\
I)! •"; ,~, "" '.\
["
1
I
i .' I 11 '{
;t"d d:Lfa
j·t~:tJ~
';'l.·"
'"
;,ttT,':::
il:'
j
tr
t
,l"'l)11l!
,I. I ' ! t ,t
i
,~
..
! it'
a'.aila~·!~·' II'
".~: .. !.! 1111' i'l!jI !'italtl'p of
t,·tt'aJ,lc)i!t ~t~~d.. +~t
"'rIll" :t\ .. tilal,!to ,lata
'.\1",-
~,1..:11l1·!~t...
!. f l .• "!" :t-,~ ... ,,;
H ~f'l'q:t' *.. !\;tT!!
tl~ t,
1::;,I'J i~a!:"p ~'It;'
~!dil'Lt~lL('1'
::t-'IJ'
,",,",f
:'~L ~t'!lt·-
)',
1111\\­
and
r
t~'
n. f',·r ...
" .. ", ..
~,\,,~~~~tlt't!
\..
:t~,
,o,pp...,pd ... ';!!rILt...
(~I'nl"it'
('tltltfJd
IIf
this
',,·tr t ' .... \ l)pll;1:"~1\t'fit IIf Plaul t·lllfttft". H'lv:d
~~;! \...'~." .: .• cd (',.l:,,!.!:.·, "iH"I1lia!.!;l';l. i)"IUl1ark
•
•.•• :
I
'1":.I..j.'l1atl\" .<;I'I·t .... \\a~ l'a\I1!I'IL
1:
\
,! 1 t . . . '.\
, , :,. :"j
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1'1
":'.'.I.r·
'L
_ : :.1
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t
I ';'
l!J
I
20
TECHNICAL BULLETIN NO. la7D, l:.S. DEPT. OF' AGRICULTURE
Yariegaled.-l'sually all 1"1 and many 1"2 and Fa progenies f!"Om erosses
betweell purple- and yellow-fiowered plant" have vnrie'mtcd flowers. This
has becn shown to be due to a (·opi$..'1nentation of the pllrple pigment!';
in the epidermal layer of the flower with a bU('kground of yellow pi.gIHents.
Gene dosages fOI' purple, yellow, and lUodifyinl!; pigments, and age of
flowrr:; w('r(' shown to lw fadors that influell('pd dpgn>(' or variegation.
II'hite.~-·\\·hite-flowered plants were des('ribcd as })Cin.U: devoid of
anthocyanill pignH:ntatioll in flowers, secds, stcms, leavcs, and I'oots.
The whitp-flowcl'pd phrnotyp(' was produ(,cd by thc homozygolls n'(,pssive
('ondition of U1(' ('olor-conditioning C gen('. The ('('CC genotype is ppistutie
over the P gene ('On trolling purple flower eolor and the Rd I!;ene ('ontrolling
rrd root (.1),
('rrum.-Crram flow('r ('0101' was due to the homozygous re(,essive
eondition of thr s('vrl'!ll gcm's ('ontrolling yrllow flowrl' eolor and the P
J!;rll(' ('ontrolling Plll'plr flowrr ('0101'. Thr J!;ellotype of (,ream-fiowered
plants did not altC'l' eolor of any oth(,I' plant ol'gan, Cl'pa,m-fiowered
plant,,; \\'C'rp rpudily difl'pl'('ntiutC'd from whit('-flow(,l'ed plantH by the
pr('sPllcC' of pigmentrd flol'al v('ins, antho('yanin,,; in the HtemR, and tan 01'
v('lIow Rt'(>ciR. - Ex('C'pt for t'fl'C'('t,,; of gC'nc dosage, diploids allli t('traploids 111'(' vcr)' ,,;imilar with rC'gnrd to tlw inhC'ritan('(' of purpl{', y{'llow, white, and ('ream flo"'{'r ('olot'. A bett{'r 1IlldcrRtandinl!; of yellow flowC'l' ('0101' inIH~ritllllt,('
and the cfl'pcts of modifying flletor~ ('an be obtained from diploids. (See
p. :3:3.)
Hornless Wing Petals
This abnormality j,,; chara('tprized by wing pptnls that fold around tIl("
k('('1 instead of ('xtending normally (fig. 18) and is ('aused by the absence of
hol'l1s on wing petals. Preliminary geneti(' analysrt; by Bames, A. W.
Hovill, and Clrveiand (data unpllbliHlwd) at l'nivcrsity Park, Pa.,
indi('at(>d that the length of the wing petal horns appeared to be controlled
by 011(' U'lrni'!omi('ally inh('rit('d grill' hi with pmtial dOlniIlHn('('. TI1l'
wing prtals of the nulliplex ).!;('notypc WPl'e hOl'1lIe"" and endoscc\ the
ked prtals. 'rhr phenotype of the simplex was similal' to the nulliplex
(,x('ppl I'DI' t 11<' pre,,;('n('(' of ,,;hort (0,7 [j to 1.2;i mi II iIllet!'rs) horllS, Tht'
wing p(>tal,,; of <!upk·x plants Wl're aPPI'(}ximatply olle-half ('xtt'nd(>d and
had hol'lli'! 1.2;i to I.(j:i millimct(>rs long. Tripl(,x and qtHlcil'llplex
gC'llot.yP('S Wl're difli('ult to difTt'J'entiate h('('allse both had nonl1ally
rxt('I\l/(>d winv; pC't.n.ls alld horns of similar icllp;ths (ahout 1.7fi mil1imeters).
,.\ ('olli'!ist('nt ddieil'Il('y of nulliplex plants was olmerved, The apparent
nlJility to icl(>lItify most g(,lIotypes 011 the hasis of phellotypes may
mak(' this a lIRdul l!;I'IlP Iluukt'l' for many f;tlldi(>s, How(>vpr, its use­
ful!l(>si'! in poll illation studies will he limitpd hp(':tllse most pollinutilll!;
insrcts arc unahle to trip flowen; of lIul1iplex 01' simplex plants.
Male Sterility (Anther Nonclehiscence)
A male stNile (nondehisl'cnt) alfalfa plant was dest'rihed by Childers
(/.1), The sterility was ('haraetcrized by a PI'C'('()('iollS development and
O\'C'I'gl'owth by the tap(>tal tissue, whi('h was uss()('iated with an extreme
vacuolution of tlte l'ytoplasm of the adjacent sporogenous celh:l. This
GEXETIC rfRAITS IX TETRAPLOID A:\,D DIPLOID ALFALFA
..
.,
.. to
21
'
t'
~f
..
• 1
.
~
A
Fwn(t; IS.-Hornless wing petal trait: A, Portion of wing Pl't:l! showing ('omplete
Illek of wing hooks; B. portion of wing pl·tal showing normal length wing hook: C,
ph('!lOtypl' of floret with nlllliplex gl'notype for hi gl~ne ('llntlitioning hornless wing
pl'tals; D, normal floret quntlruplex for hl gene.
Iradg to a dr)J;rn('ration of the pollen mothpr ('rl\s in the early prophase
sta).t'r. Hr::wy-wal\rd pollen grains werr somrtimeg presrnt at maturation
of anth('l's, but the shrunken naturr of thr ant\trrs pre('lucied the possibil­
ity of anthrsis. Inh('l'itanee of this nondehis('PIH'C type of sterility was
attributed to at,tion of ciuplieate genes <.msl and mS2) with di-;omic inheri­
22
TECHNICAL BULIJETIN NO. 1370. U.S. DEPT. OF AGRICULTURE
tanc'e. Plants having a homozygous recessive genotype, mSl mSl mS2 mS2,
were nondehiscent, but the presence of one or more dominant alleles at
either the Jl Sl or Jl S2 locus restored abilitv of anthers to dehisce. Childers
indicated that because F3 populations were not included in the study, no
attempt was made to determine whether tetrasomic inheritance was
operative.
Male Sterility (Pollen-Grain Degeneration)
Childers and ~[('Lennan (16) described an alfalfa plant that was eom­
pletely male sterile under greenhouse and field eonditions. :Male sterility
was eharaeterized by an atypieal behavior after micros pores were released
from tetrads. Complete degener&tion of micrm;pores followed. The stage
at which this degeneration occurred was later than the stage at which the
nondehiscent type of male sterility reported by Childers (J 4) occmred.
Function of the female gametophytes of plants with degenerate micro­
spores was normal. Oenetic studio!'> indieated that eomplete male sterility
was rontrolJed by three reeessive genes, whieh were probably inherited in
a disomie manner. A tetrasomic interpretation was not diseoullted, how­
ever. Xo eytoplasmic factors were assoc-iated with thi5 type of male
sterility. Subsequently, MeLennan and Childers (33) transferred this
mille sterility from the' t.etraploid to the diploid level and showed that
the trait was controlled by OIlC gene IIlSa instead of three disomie genes.
(See p. 83.) Thus, they ('onl'lucled that olle gene with tctrasomie in­
heritante W[lS responsible for this form of male sterility in tetraploid
alfalfa.
Open Keel
Nielsen (86) described alfalfa flowers with abnormally open keels and
separation of keel petals (fig. 19). Expression of this condi­
tion is best at relatively low humidities and high temperatUl"es. Most
flowers with the open keel trait are more easily tripped by honey bees than
are normal flowers. Preliminary studies indicated that inheritance of the
open keel trait is probably simple.
lon~itudinal
Poc/ Hairiness
Ac('ording to Armstrong and Gibson (1), pods of J[edicago glulinosa
Rich. are C'hamcterized hy upright hair!'>, ea('h hair exuding 11 !'>tieky
glohule from thc tip. Arm!'>trong and Gihson !'I'os!'>ed M. glulino.sa with
a plant of :ll. media Pers. that had appressed pod hairs. The;1[. glulinosa
traits were dominant. in thc Fl generation. F2 families :-;egregated in
ratios of either :3 upright : 1 appressed, or appl"Oximately :3 upright : 4
intermediate: 9 appre:-;sed. Arm;;trong and Gibson postulated that. Jr.
gllliinosa earried a dominant factor G for upright hair postUl"e, and that
the M. media parent was homozygous for the recessive g allele and heter­
ozygous for a faetor I. It was also postulated that the [ allele partly
inhibited the expression of O. Thus, the proposed genetic tonstitution of
the 111. gllliinosa and .II. media parents were OOii and ggli, respectively.
Inheritance was based on a disomic scheme. The authors did not test
for tetrasomic inheritance.
GB:XE.TIC TRAITS IX
TI~TRAPL()ID
AXD DIPLOID ALFALFA
23
Hu('rmp with floll'l'r~ showing open kl'pl trait ('m'oll'), «('\lllrtes~'
Ilr'parluwnl "f Plant ('111' "I'l', Itll~'al \'eterinary and Agrieuhu'al College, Copen­
hagen, Denmark,)
FT"r Tn; I!L
Seed Color
:\[a(.Yicar L3j) Ilotrd that ~r('{1 ('0101' of alfalfa wa:; prcdominantly a
bridlt grc'('ni~h yrllow hut that dCIl~ity of ('0101' rangrcl from a ycry light
\'p\low to orang!' 01' light hroWll, Ex('cptiollll.1 plant:; with truc hla('k 01'
tl'lH' \\ hit!' ,,('('d~ \\'('1'(' i:'olat('(1. A j)\a('k-,;C'('l\!':\ plant \\'a" di,,!:On~red in
tile third genemtion :;elfed line of variety Grimm,
24
TECHNICAL BULLETIN NO. 1370, U.S. DEPT. OF AGRICULTURE
Black.-F2 studies by MacVicar indicated that white-seeded plants
were homozygous for a recessive factor V, whieh resulted in the absence of
yellow pigment. Inheritance of the black-seeded trait was faidy eomplex,
requiring a hypothesis of at least three factor pairs. Black color was
attributed to a single /2:ene mutation, whose expres:,;ion wa:,; affe('ted by
two modifyin/2: genes. The genotype of the original blaek-seecled parent
was postulated to be YYC I C I C2C2 Bb, where the genes arc represented by Y
for yellow pigment, B for black pigment, and ('I and O2 fOI' factors that
modify the expression of blaek. Dcfieil'nt'il's, whieh were attributC'd to
elimination by gametic or zY/2:otic lethals, were noted in black and deep
mulatto classes. No reference was made as to the possibility of tetrasomic
inheritance. Seed coat eolor was atIected somewhat by environment.
While.-Alfalfa plants with white seeds were described by MacVieal'
(34), Oldemeyer (88), Risius (46), Stanford (49), and Walch'on (.14). The
mutant plants had albino-white or l'l'eul1ly-white seeds, whieh were
distinetly ditTerent from normal tan or yellow seeds (fi/2:. 20). Plants with
white seeds had white flowers and lacked anthoeyanin pigments in foliage.
'Waldmn stated that white seed color was inherited in the same manner
as white flower ('olor. ::\[a('\,iear reported that white seed ('0101" was
recessive to tan and that the differenee was ('onditioned by either one or
two genes with disomie inheritanee. Oldemeyer studied seed color inheri­
tam'e in 1"2 and backcross generations of crosses between plants having
white seeds and white flowers and both plants having tan seeds and
purple flowers and plant>; having tan seeds alld yellow flowers. He ('on­
clU'led that white seed color was produeed only when a colol' gene c was in
the homozygous recessive condition and when a dominant allele of an
inhibitor gene was present. Howc\'cr, neither l\IaeVi('ar nor Oldemeyer
grew the eritical generations necded to positively establish the number of
genes and type of inheritance. Risius and Stanford later demonstrated
conelusively that white seed color and white flower color were both con­
trolled by the same single recessive gene (c) with tetrasomic inheritance.
FIGURE
20.-A, Normnl yellow seedsi B, white seeds.
GENETIC TRAITS IN TETRAPLOID AND DIPLOID ALFALFA
25
FI(;(THE 21.-Variations in floral structure produced h~' vestiJ1;ial cornlla t.rait. (Cour­
tesy ('entral Experimental Farm, Canada Department of AJ1;riculture, Ottawa,
Ontario.)
Vestigial Corolla
A floral mutant with a variable corolla (fig. 21) was isolated by Pankiw
and Bolton (89) in the SI progeny from an alfalfa variety Vernal plant
with high seed set. Nectar production was below that of the parent.
The nedary was at the ba!'le of the staminal column in some florets, but
was below the anthers in others. Pollen production of this mutant was
limited but pollen was viable. Self-fertility was low but cI'oss-fertility
normal. Honey bees visited the mutant flowers and some seed set
resulted. Pankiw and Bolton (40) studied the seed-product.ion possi­
hilities of this mutant and ('oneiuded that the various types of vestigial
florC'ts produ('ed might bC' useful for imoroving pollination by honey bees.
Pankiw and Goplen (41) reported that the vestigial corolla trait was
('ontrolled by a single reeessive gene (vc) with tetrasomie inheritance.
The expression of the L'C !l;ene was subjected to considerable environmental
influence.
Vestigial Flower
Duelley and Wilsie (!'dS) descrihed a mutant plant with profusely
bran('hed, panicle-like inflorescences (brane·hed raeeme) and vestigial
floral parts. Only an oC'casional petal was normal sized (fig. 14). Seed
sC'tting was not observed to occur in the field. Genetie studies indicated
that the brane'hed raeeme and vestigial flower traits were related, but the
basis for the relationship eould not be determined by the data.
1n a subsequent publieation (24) the same authors proposed symbols
f), 1-, P, and pi for genes associated with the vestigial flower trait. D
and \' were assumed to be tetrasomic genes with random ehromosome
sCl!rC'!!ation; P and pi were assumed to be duplieate disomie genes.
S0111C' genic interactions were noted. The authors C'oncluded that the
vC'stigial flowpr trait would be of little value as a genetie marker heeause
of the difficulty in making erosses and the eomplexity of genetiC' meehan­
isms involved.
26
TECHNICAL BCLLETIN NO. 1370, IT.S. DEPT. OF AGHICULTURE
Plant Resistance Downy Milclew Resistance Infected leaves of alfalfa plants attaC'ked by the downy mildew fungus
Down\" mildew ('auses
si!!nifieant leaf drop and seedling damage durin'~ cold, wet weather.
.Tones and Rmith (28) suggested that susceptibility was dominant to
resistanc'e. PedC'rsen and Rame:; (.13) reported that resistanc'e to down\'
mildC'\\" appearcd to he due to one tetrasomieally inherited !!:cnc with
in('omplete dominan{'e. 'I'his genc was designated Dill. Thc le\'el of
resistalH'C' appeared to be determined hy ac;eulllulati\'c genc action with
gcnotypes as follows: \'('ry :msccptible plant::; = nUlliplcx ~cnotyp(':
moderately :;u:;C'C'ptibl(' = simplex; moderately resistant=dllplex; and
resi,·;tant=triplex or quadruplex.
It was suggested that ('onflieting
l"C'ports as to the modC' of inherittll1('C' of do\\'n~r mildew rpsistull('e in
alfalfa might be C'xplained by thc C'xi:,t(,l1C'C' of hiologic'al m('C'" of P.
Peronospora Ir~roliorllm DBy. be('ome yellow.
lrifoliorlllll.
Pea Aphicl Resistance
The pC'a aphid AC!Jrlhosiphon pisllm I Han'is) eausC':; yellowin~ and
stunting of alfalfa. JonC's, Rri.ggs, and Blanchard (2,9) determined thc
inhC'ritan('e of rC'sistan('C' in plants traeing to the variety C'hilran. Thcy
eagp(\ sel'ond-instar nymphs and ob:;el"\'cd mte of n\'mphal prodtlc,tion
and length of production period. On thc re,·;jstant parent. second-instar
nymphs lIsually failed to reach maturity in the normal time and upon
maturity produccd few, if any, nymphs. The lell)!;th of life did not
eX('('ed 9 days. On the sus('t'ptible parent, from 4 to 9 nymphs were
produced per day for a period of 10 to 15 days. F~ and F:l seg;rc~ations
indieated that rc;;i:-;tanC'e was C'ontrol\ed by one dominant gene Pa and
one rcC'ei'si\'c p;ene pro The desi~natjons A and b were used in the orig;inal
publicatiol1 hut wcre not il1tended as p;eneti(' symbols. The :;ymbol:; Pa
and pr were :;uggested by F. X. Bl"iggs.~ Both gpl\es were a:-;:;umed to be
inherited in a disomie manner. The proportion of homozygous to heter­
ozygous families suggested a linkage between the two genes with a CI:OS8­
over value of about 28 percent. The authors were unable to explain
segrpl!;ation on the basis of random ehromosome segregations of an
autotetraploicL
ReC'ent reports have shown that plant reaction to the pea aphid may be
affected by environmental (·onditions.
Root-Knot Nematode Resistance
Goplen and Stanford (25) used nematode rcpl"Odut'tion (prcsenec of
egg masse:;) as ('I"iterion for e1assifieation of resi:;tanee to root knot (fig.
22), a disease eauscd by species of the p;enus J[eloido{Jyne Goeldi, 1887.
Root l!;alIinl!; al\ci proliferation are eommon symptoms of the disease.
Rtucii('s of rrsistallee in two sclcctiom; from the variety Vrrnal showed
that resistan('e to ,1/. hap/a Chitwood, 1949, was eontroil('d by one domiS BWGGs,
F.:-;.
:-'Illrch 23, 191H.
lPersonal correspundence.]
GENETIC TRAITS IN TETRAPLOID AND DIPLOID ALFALFA
FHH"HE 22.-:\ and C', Plants 8u;;('eptible to root-knot nematode;
n, plant
27
re.~istanl
to root-knot nematode.
nunt gene Rkl with tetrasomic inheritance. Limited genetie data from
two ot\wl" plant selections suggested that Oil(' or two additional f,!;enes also
NHlf(,ITed resistan('('. Similar inheritanc'e studies dcmon!itrated that
r('"istanC'e to .1/. jm'anica jm'anica (Treub, 1885) Chitwood, 1949, was
('ontrollrd by one dominant, tetrasomiC' gene Rk~ and possibly a second
gPIIC'. The Rkl and Rk2 genes were linked, but an estimate of linkage
int('!!sity was not obtained.
Stem Nematocle Resistance
Alfalfa sppdlings attacked by the stem nemutode Dil!flenclLlls dipsaci
Il\:uhn, 1857lFilipp\', 1936, develop a swollen ('otylendonary node and
;;wo\lc'n and stunted leaf petioles (fig. 23). Older plants have swollen
stpms, shoots, and petioles, as well as distorted leaves and petioles.
{;rulldbu('k('r and Sttwford (26') reported that re;;istane(' ill all Imllia!!
introduction, P.I. 141462, and possibly in the variety Talent was condi­
tioned by one dominant gene with tetrasomic inhel'itance, The I'esistant
),!;P[W in th(' Iranian selection was designated Sn hy Stanford. 9 Grund­
lJaekt'r and Stanford (26) reported a second type of resistance controlled
by on(' or more minor gellcsin introductions from Argentina and in
l'('si:-;tant selections from the variety DuPuits. Segregation in progenies
from erosses of the variety Lahontan eould not be illterpreted on a factor­
ial I>u:-:i:-:. Controlled temperatures were necessary because expression of
nematode symptoms was temperature sensitive. Xumbers of nematodes
and Pggs were used as eriteria of resistam'e, Previous studies on stem
npmatod(' rpsistanee by Burkart (12) and Ragonese and ~'lal'('o (45) sug­
gpst£'d a multifactorial system,
9 ~,[,A:-;~'OIW,
E. H. July 10, 1963.
[Personal correspondence.]
28
TECHXICAL BrLLETI~ XO. 1370, c.~. Dl~PT.
FJnl"l!~;
2:t-.t and H. S('('cilings
s\l~("f.'ptihl('
to
~t(,1ll
()l<'
AGRICCLTURJ.;
llPlllatod('; (', ;';I'pdling rpsist:lnt
lo slt'm 1\t'm:tlodt',
DIPLOID ALFALFA (2N = 16)
Leaf and Stem Traits
Cotyledon Chlorosis
Barll(';'; and (')c\'('lan(\ ((lata unpuhli.shcdl at rni\'er:;ity Park. Pa..
ol,s('t'\:('d that s('cdlings from a (TOSS hct\\'C'ctt (\\"O lIlll'clated h\"hrids of
.11 Hlim{lo salim alld .1/. folcala segrcg-ated for grccn, yellow, a;,cl white
c'otyIPdOll ('0101' (fig;, 2,1). CC'nclie .studie:, imlicaH·d that ("0101' was ('Oll­
trollC'd by two inti('pcn(iC'nt gcnes (/1' and }'c, whieh sep;rcgaled in an F~
ratio of 12 greC'11 : ;; .n'lIow : 1 alhino. TIt(, dominant allele of the (Ie
g(,llP was C'pi;.;tati(' to hoth allele:; of the }'e gene alld pl'odu('ed green
('ot\"ledons, In til(' ahsC'Il('e of a dominant (j(" allel(" the dOJl)inant }Oe allele
PI"O'dlJ('C'd yellow ('otyledons. ::-;('edlings that W('l'e hOJl)o7.ygolls re('essl\'e
for both grlle" werc albino and lii('d a fpw lit),)," after pJ1)C'rgclH'e. Ycllow
s('pdling.s dicd within .scveral weeks. Tn addition, cither gameti(' or
7.\'gotic', or hoth. illviahilitiC'.s S('('l11p<I to han' (':uls('d ahout :L ;{;{-p('J'(,plll
tlpfil'ipn('y of yc:lIow ~epd ling!:' and ahout a i)O-IW1TCllt ddiei('IH'Y of alhino
s('('dling!'.
:\n asso('iation was notf'd !Jpf\\'PC'1l ('hloroti(' ~('('dlings and multiple
('otyl('(\on:-;. III thp original (TO!':-;. multip\(' ('ot.~·kdolls ,,"prp ol):-;('I'\'pd on
abollt iO PPI'('['l1t of till' albillo ~('('dlillgs, lO P('I'('('1I1' of thp y('llo\\' sl'edlings.
and Dilly I pcrcellt of the grcl'll .seedlillgs.
'.":
~
.",
., t·
i
n
~'.
30
TECHNICAL BULLETIN NO. 1370 1 U.S. DEPT. OF AGRICULTURE
Crinlcled Leaf
A crinkled leaf trait similar to that shown in figure 2 was observed by
Barnes and Cleveland (data unpublished) at Cniversity Park, Pa., in
the advanced generations of a cross between diploid JI. saliva and diploid
M. falcala. This trait appeared to be phenotypically similar to the one
reported in tetraploid alfalfa by Odland and Lepper (37). In clones
having a severe expression of the trait, the crinkling was apparent at all
stages of growth, but crinkling in clones with a less severe expl·ession
became most apparent on the early aftermath growth of established
plants. F~ progenies segregated 13 normal to 3 crinkled, indicating that
crinkled was controlled by two genes el and Crl. (The el and Crl gene
symbols were selected in order to correspond with E and Cr symbols
suggefited by Odland and Lepper.) Presence of aL least one dominant
allele at each of the two loci or the homozygous recessive condition of the
two genes resulted in normal leaves. Crinkled leaf plants were produced
when one or both of the alleles at the Crl locus were dominant and the el
locus was homozygous recessive.
Lutescent
Coty/eclons
Barnes and Cleveland (data unpublished) at University Park, Pa.,
found seedlings in adyaneed generations of diploid JJ. saliva X diploid
M. falcala hybrids with yellow-green cotyledons at emergence. Several
days later the color of the cotyledons usually darkened in the vicinity of
the cotyledonary axis and veins (fig. 25). About 1 week after emergence,
25.-A, Newly emerged lutescent seedling; B, cotyledons becoming darker
green; C, normal green cotyledons. Chimeral sectoring usually is present in uni­
f oliolate leaves.
FIGt:RE
GENETIC TRAITS IN TETRAPLOID AND DIPLOID ALFALFA
31
th(' cotyledons became normal green throug;hout. Lutescent cotyledon
appeared to be controlled by two complementary genes Lei and LC2.
Plants with the g;enotypes LCI -Lc2 - had normal g;reen eotyledons;
plants with LCI-lc2 /C2, lCI lCI LC2 - , or lCI lCI lC2 /C2 g;enotypes had yellow­
J!reen eotyledons. All g;enetic data were obtained from cotyledon color.
H owevcr, unifoliolate and trifoliolate leaves usually had a sectoring;
trait (fig. 25). The deg;ree of sectoring varied; some plants had slight
::ipdoring on only the lower leaves; others had sectoring throug;hout. It
was assumed that sectoring; was attributable to the same genetic control
as the yellow cotyledon color.
Mu/tifofio/ate Leaves
Bauder (8) reported that some tetraploid alfalfa plants had multi­
foliolate I('avcs instead of the normal trifoliolate lea\'es. Bingham (9)
found plants with this trait in both diploid and tetraploid populations
(fig. 26)' Leaflet numbers ranged from three to nine among tetraploids
and thrc(' to six among; diploids. Diploid genetie studies indicated that a
r('crssive gene (mf) in the homozygous condition was necessary for the
proc1tH'tiol1 of ll\ulti[oliolatC' leaves. Penctrallc'C' ranged ft'om incomplete
for plants with prC'clominately trifoliolate lcaw,; to ('omplctc for those
with prrciol11illat£'ly multifoliolatc leaves. DifTC'rcllees ill penetranee
WPI'(' explnitH'd on thC' basis of two aclditi ve gene,.; with three alleles for
C'llC'h gpfl('. Bingham and :'IIurphy (LO) reported that this trait wa!';
highly herit!lblc in tetraploid alfalfa and the mode of inheritance ap­
pt'are<l ;.;imilar to that at the diploid level.
FH;t"n~:
26.-.\lultifoliolate trait in diploid alfalfa, Expression is similar in tetraploid
alfalfa. (Courtesy Department of Plant Breeding, Cornell University.)
32 TE('IIXIC'AL 13l'LLETI'\" XO. l:j70,
{'.s.
DEPT. (H' Anl{J(TL'lTHlo;
Flower and Seed Traits
Calyx Pigmentation
C'le!11C'llt 10 ollsflrn,d fi('c'b; llf alltho('\'unin pignlC'll!ntion ilig. 2il on till'
c'aJyx of Romp diploid .11. fa/mia, diploid .II. '~(ltil'U. aLld t!'trn.ploid Jf.
salim plantR. TIl(' !I'ait ('orrpspollds "los!'l), to OU(' d(''';c'I'ii>!'d hy SC'hro('k
• ;8- ill l{'(raploid plant;;. fllh!'l'iltUH'(' ,;tlltiip . . ill diploi,l alfalfa hy ('I('L1H'tI[
d('molt~tratr'd thnt ('alyx pignwutn[ioll \\'a~ gm'(,I'!Jpd hy It ;;inl!;l(' dominant
g('tll' ('p. 1'1'!'limlnary data in tt'tmploid alfalfa indl!'atl'd that pkuU'llla­
lion i:-; prohably dl'l('rlllinC'd hy a :-;ingll' dOlllintlllt J!('Jl(' illhl'J'itet/ ill n.
tc'tra"Ol!l it· IlUlIl Itpr; hO\\'('YC'r, data OIl I'l'i t ieal gPIll'rnt iOlls an' Ill'eli{'d
\1('fol'(' tili::; hypoth(>!'iR ('Ull he cBtablislH'd.
.
~
;
,~,
{ •.i:,I:
<
d.
FIf;l"n~: 27.-· Flowf'r hud;: ;:h()wil1~ rhllr:lf'tf'ri,1 il' f1f'('kiIl~ or ('all·... pi~Jllf'nl III inn
pIH'Illltypt'.
GENETIC TRAITS IN TETRAPLOID AND DIPLOID ALFALFA
33
Flower Color
Results of studies of the inheritance of flower color in diploid alfalfa
have' hN'n puhlii'hed by Buker and Davis (I I), Cooper (18), Coo pel" and
Elliott (19,20), and Twamley (53). The information from these studies,
as well as unpuhlii'hed data from other \'esearch worker!>, was summarized
by Barnes (8). A digest of genetic mechanisms conditioning flo we'!' color
follows. For the sake of brevity, further referelH'e is not made to
ol'igi nn.l papers.
Pw·pie.-Chemicai analyses of diploid alfalfa indicated that purple
flower color was due to three antho(·.yanin pigments inherited as a unit and
C'oJltl'OIIed by one dominant gene (P).
YelloU'.- Yellow flowel' color pigments in diploid alfalfa were identified
as being primarily xanthophyll with a small amollnt of f3 C'arotene
pt'('sent. Genetic' data suggested that yellow flower color was controlled
by at least three and probably four genes with ac('umulative effects.
Two of the genes controlling xanthophyll were designated YXl and YX2.
Thr other two genes were designated Ya and Y,I hut were not identified
with any speeifie pigment.
"ariegaled.-AllF\ and many F2 and Fa progenies from erosses between
purple- and yellow-flowered plants have varie)!;ated flowers. This has
1>('('11 ;.:howlI to he due to a ('opi!2:llentation of thc purple pigments in the
t'pidermal layer of the flower with a haekground of yellow pigments.
Deg('ee of variegation was shown to be influen<'ed by dosages of pmple,
yt'\1ow, tlnd modifying pignwnts, ulld hy age of flower.
('ream.-The homozygous recessive eondition of the four genes eondi­
t ioning yellow flower color and the P gene produees a ('ream flower ('olor.
Th(' f!enotype of the (Team-flowered plants did not appear to alter the
pipll('ntation of other orp;ans of the plant.
Whi/e.-\yhite-flowered plants were completely devoid of anthol'yanin
pij!mentation in flowers, seeds, stems, leave;;, and roots. The white
pIH'!lotypc \Va.'; produced by the homozygous l'eee;;sive condition of the
('olor-C'onditioning c !!;ene, which is known to be epistatic to the P and Rd
g(,ll e;.:•
.If oeliJuirtg piamenls.-Nine anthoxanthin pigments were chemically
identified in diploid alfalfa. Three of the anthoxanthins were kaempferol
)..dy('o:,i(\{>:-;; "ix wc'n' quer{'etin gly('oside:,. ~()II(, of the pi!J;mellts appeared
to impaJ't a phenotypically significant color of its own, but each tended to
ha\'(' a modifying efTect when eopip;mcnted with anthocyanin OJ' xantho­
phyll. The inhcritaneo of production of two kaempferol p;ly('osides was
('ontl'olled by two dominant independent !l:enes designated K2 and K a•
No association or linkage was detected among the P, YXI, YX2, K 2 , and
KI genes in diploid alfalfa.
Male Sterility (Pollen-Grain Degeneration)
:\ I ('Lrl\nan find Child('!'s (33) transfrJ'red the ('()\1Ipletely male stet'ile
trait, previously described on page 22, from the tetraploid to the diploid
I('V('\ by crossing the male sterile tetraploid with diploid forms of Jr.
salim, .11. Jatta/a, and .ll. hemicycla Grossh. to producc triploids. Back­
(\,UHse;; to the diploid spceies produ('ed Hi chl'Omosome plants, two-thirds
of whieh produced selfed progenies segregating 3 : 1 for male sterility.
;34
TECHNICAL BCLLETIN NO. laiD}
r.s.
DL;:'PT. OF AGRICULTURE
Further 1"2 and backcross data showed that the ('ompletC' male sterility
factot· was !!;overncd by a single l'eecs;:;ivc gcnc 1I!SI' These data indieatcd
that this form of male sterility ill tetraploid;:; \l'a."; ('ollciitioncci by a single
gene inherited in a tetrasomic manner instead of thrce disomic genes as
originally postulated.
Ovule Number
Si!!;l1ifirant difTerenees for a verav;c ovule numlwl' pCI' floret wcre obsct'ved
by Burnes and Cleveland (5) in plants of tetraploid and diploid alfalfa
(fig.2H). The avera!!;e lIumber of ovules pCI' floret was l'clali\,(oly eonstant
among l'U('cmcs of the samc plant, but difTered slil!;htly amollg f10rcts of
the same l'al'CIl1C. In diploid alfalfa, the average o\'ulc lIumber pel' floret
sCV;l'c!!;ated into 5 distinct ovule number eia;.;;.;('s, whieh averaged approxi­
mately 7.0, 8.5, 10.0, 11.5, alld 13.0 ovules. Four WOlles with accumulative
A
Fll1um; 28.-11, Ovnry having 6 ovules; B, ovary huving 17 ovules.
Id.\Ll'W TH.\IT:-; L\ TETlL\PL()lf) .\\[J IJlI'L()ID ALFALFA
:35
',\,·r'· a--lIl1l1'd for Il"ul" Illllllbp!" '1'111<"/' IIi t111''';P!!;t'IH''':, {)I'l, ()I'~,
-LtJ\\'I·d rwarlv '<[)ll:pld,' t\otnilulIll'" wbih· thl' fOUl'th, ()/'"
"\l'!''''',j llwllwpl,·rt> d(Jllliltall"". Till' 7.IJ-Il\·!I\p ,'la·" \\'a,.: attl'ihtltl'd to
~ !., I ... :;,"/.\ l!1J1J- n""'"ivl' 'IJIHlitioll of all i"'II' !!;!'ltI'", Tit!' PI'P;;l'IH'l' of
•.• !," 11'< IW.j'(' dl)IlIiltallt ulll'h',,; at allY OIH' of til!' illllI' 1')I'i rai:'l'd till' ll\'pl'lVre
',',l;'< 1I'ud·{'J' 1'['1' till!'!'! :tpprl1:xilll~ltl'ly 1 ,-) 0\,111"..;.
,.,
,.!! •. , t-
:u.d (I
Purple Bud Color
\lall', \ 11Iow-floWI'l'l'd alfalfa plant.; pxllil,it tlllth'lI'yallill pi!!;Il1Pllt at
; :.1 t II' Ii:! :!!I
Tlti- pi!.!lllt'nt 1I-lIally fad,,, at all! hl',.:i~, TIH' ()('('UI'­
"'.,., ..f f"l!'!,l!' hlld ,'oltl\' ill.\'I,llow-!I0WI·f'(,d piant..; IIll..; IH'l'lI I'l'po!'tl'd oniy
::. t.1 ":':'·!li..• 01 till' ,'ro--. Plll'p\!'-lIoWI'l'l'd ,l!. ,,1// /I'll .<' ,n·llow-flO\\'('I'('c! Jf.
,:', '7',1
Bill It ("IOIll'\' 1'1 all.! TWallli!'\' .,.) 1l!'-I'ITI,d tlti~ hud-l'oio!'
! .;:r", l:!
Lilt tlPi!!,,'!' d"tl,t'llIilll'd il" Illotil' of ill!H'ritnlll'p, l~a!'I1(''; and
{ ;•. ', ,·;:tllli ,: , i!'[('l'IlIi{H,d t hat purple Illid ('olor \"('q uil'l·d t Itt' pr('~(,Ill'(' of
,i .•
.1. BIlt! .. f nUllw flOII'['1' wilh [llIrplp 1l1lIhfl('\'!lllin pigllH'nl'; at tip; H,
1 ' I '. ,';1..\\ t! .. \\ "I' .!"Yflld IIf \,1~ll,!t, ani hnel'lluin pigllll'nl". ! ('tlllrtl'~,I' ,\groIlOITI.I'
1)"1':11'111"'11', 1"'I1lI~Yh"I!IIa :-\fat<' l'l1iYer"ity.!
II'" ,;:2'1
• 'j'
36
'rECHNICALBULLETINNO. 1370, l!.S. DEPT. OF AGRICULTURE
two dominant genes with complementar:r action and postulated genes
Bs and Bj, one each from JI. saliva and JI. falcata, respectively.
Vein Color 01 Standard Petal
Darkly pigmented veins occur with varying intensity in the standard
petal of most alfalfa flowers. The veins begin in the throat of t.he flower
and extend toward the forward edge of the standard. Because either
purple or green petal color reduces the prominence of floral veins, Barnes
and Cleveland (6) determined the genetics of vein color in yellow­
flowered diploid alfalfa. Some plants had veins throughout the standard
petal; others were completely devoid of floral vein color (fig. 30). The
occurrence of darkly pigmented veins in the standard was controlled by
duplicate genes r 81 and V 82. Presence of one or more dominant alleles
produced darkly pigmented veins. The homozygous recessive condition
of hoth genes was associated with absence of vein color. An association
between pigmentation of veins in standard and wing petals was observed
but was not interpreted genetically.
FIGURE
30.-A, Floret having pigmented veins: B, floret lacking pigmented veins.
(Courtesy Agronomy Department, Pennsylvania State University.)
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