Download Inheritance and genetic mapping of leaf rust resistance genes in the

Inheritance and genetic mapping of leaf rust resistance genes in
the wheat cultivar Buck Manantial
1
Altieri E 1, McCallum B 2, Somers DJ 2, Sacco F 1
Instituto de Genética “E.A.Favret”, INTA Castelar, Argentina . 2 Cereal Research Centre, Agriculture and Agri-Food
Canada, Winnipeg, Canada
ABSTRACT
Leaf rust, caused by the biotrophic fungus Puccini triticina,
is one of the most important diseases of wheat worlwide.
The use of resistance genes is of great interest in numerous
breeding programs. Our objectives were to determine the
number and characterization of resistance genes to wheat
leaf rust present in Buck Manantial, an Argentinian cultivar
that shows durable resistance. Also, we sought to identify
molecular markers that can be used in marker assisted
selection for these resistance genes. A genetic linkage map
of 533 Amplified Fragment Length Polymorphism (AFLP)
and microsatellite markers was developed. We identified
and mapped the genes Lr3, Lr16, Lr17 and an adult plant
resistance gene (APR) named BMP1. The BMP1 showed a
high effective resistance to natural infection of wheat leaf
rust in field test in three different locations during 3 years.
The study of traditional wheat varieties of South America
origin showing durable resistance is of great value, as they
can provide new sources of resistance to this disease.
INTRODUCTION
Leaf rust incited by Puccinia triticina Eriks., is a worldwide
disease of wheat and causes important yield looses in
temperate regions where wheat is grown. Resistance to leaf
rust in wheat cultivars had always been one of the main
objectives in breeding programs. The use of resistance
genes represents a cost effective and environmental-friendly
way to control this disease in wheat. However, this
approach demands a constant effort to identify, characterize
and incorporate resistance genes, mainly due to the great
capability of of rust populations to change (Ingala et al,
2003, McCallum et al, 2005). Durable resistance, based on
the action of minor genes, and composed of seedling and
APR genes, is a desirable trait in current breeding progams
compared with resistance given by simple race-specific
genes. In Argentina, several old cultivars that show durable
resistance as Sinvalocho MA, Pergamino Gaboto, El
Gaucho and Buck Manantial have been identified (Favret et
al 1983). Buck Manantial (released in 1964) has been used
as a source of resistance to wheat leaf rust not only in
Argentina, but also in North America and Eastern Europe.
The complex genotype of this cultivar, composed of several
resistance genes, makes difficult the study and
characterization of APR genes, probably, the main
component of durable resistance. Dyck (1989) determined
by genetic analysis the presence of the seedling resistance
genes Lr3, Lr16 and Lr17, the adult resistance gene Lr13
and one unidentified adult plant gene, suggesting the
presence of Lr34 based on infection type and leaf rust
reaction under natural infection. Saione et al (1993)
concluded that 4 to 7 genes must be defeated to
overcome resistance in Buck Manantial, at seedling
stage.
The use of molecular markers and mapping
softwares can help to develop saturated linkage
maps and determine the genetic position of
resistance genes and study for the presence of
putative QTLs. Linked molecular markers can be
used in the introduction and selection of genes in
breeding programs.
The objectives of the present work were to
determine the number and chacterization of
resistance genes to wheat leaf rust present in Buck
Manantial and also identify molecular markers that
can be used in marker assisted selection.
MATERIALS AND METHODS
An F8 population of 118 recombinant inbred lines
(RILs), coming from a cross between Buck
Manantial and the susceptible genotype
Purplestraw was phenotyped at seedling and flag
leaf stage with different races of P.triticina to
characterize and map the resistance genes.
Procedures for infections and scorings were made
following procedures described by Dieguez et al,
(2006), both for seedling and adult resistance
genes.
A genetic linkage map of 533 AFLP and SSR
(Single Sequence Repeat) molecular markers was
developed with JoinMap v3.0. The AFLP and SSR
analysis was carried out according to Vos et
al.(1995), and Roder et al.(1998) and Somers at al.
(2004), respectively.
RESULTS
Three races, coming from the Instituto de Genética
“E:A.Favret” (INTA) P.triticina collection, were
used to infect the RILs population and the nearisogenic Thacther lines. These races allowed the
identification of seedling resistance genes present
in Buck Manantial. The race Ma-05 Onix detected
the Lr16 (Pχ21:1= 0.92), the race Rq-05 Cronox
detected Lr16 + Lr17 (Pχ23:1= 1) and the race 66
that detected Lr3, Lr16 and Lr17 (Pχ27:1= 0.66).
Another race, Ca2Lr17, was used to detect an adult
plant resistance gene, named BMP1.(Pχ27:1= 0.47).
For genetic mapping of Lr17 and Lr3 genes, the
1
suscetible RILs to Ma-05 Onix and Rq-05 Cronox were
used, respectively, to obtain the phenotypic data.
The Lr3 gene mapped on the distal end of chromosome 6BL
(Fig. 1a), as previously reported Dieguez et al, (2006), the
Lr16 gene on the distal end of 2BS (Fig. 2) and the Lr17 on
the distal end of the 2AS (fig. 1b) also as previously
reported McIntosh et al, (1995). The BMP1 gene mapped
on chromosome 2B and for this reason this chromosome
was saturated with molecular markers (31 AFLPs and 19
SSRs ,Fig. 2). The BMP1 mapped at 1.3 cM from Lr16,
suggesting a closely linked gene to Lr16.
The BMP1 gene showed a high correlation for resistance
under natural infection conditions of wheat leaf rust, as
demonstrated in field tests in three different locations
during 3 years (Test F for pustules/cm2= 0.001).
a)
b)
0.0
P31/M34-120
0.0
g-636-
5.3
7.5
11.4
14.0
P43/M40-186
P35/M32-110
P31/M42-230
P32/M39-125
4.8
5.3
P36/M39-80
b-124b- w-382a-
29.7
34.1
39.3
44.0
48.3
51.1
52.1
52.9
53.6
53.8
54.5
56.1
60.8
61.8
67.1
74.3
75.4
81.6
85.2
85.6
86.0
86.4
86.9
87.4
87.7
89.1
P39/M41-130
P35/M32-155
P34/M37-280
Xgwm626P36/M31-125
P37/M39-105
g-191bg-107cg-193g-133bg-107bP33/M41-273
P34/M41-125
Xgwm219P34/M33-225
P31/M40-190
b-134P38/M31-275
P34/M32-192
P34/M35-120 Lr3
P33/M36-325
P43/M40-202
P33/M40-202
P36/M32-75
P36/M39-170
P31/M40-240
0.0
2.4
4.2
4.8
g-71ag-359P36/M36-85
P36/M32-85
13.4
P34/M42-270
28.2
g-296a-
0.0
w-827a-
9.1
11.7
16.7
17.4
18.1
24.0
Lr17
P33/M33-170
g-4bg-71bP38/M42-318
P34/M42-165
P34/M33-275
0.0
P37/M33-160
8.1
w-181-
13.5
g-356-
17.4
20.3
22.7
P34/M40-84
P34/M40-210
P31/M36-220
28.9
29.9
30.8
P38/M31-80
P32/M42-250
P32/M31-205
35.9
P32/M35-210
Buck Manantial based on the allele detected by this
molecular marker (Fig. 3).
0.0
1.2
1.4
2.0
2.1
2.4
2.6
3.2
3.6
4.5
12.8
14.5
15.0
20.2
32.9
39.9
42.2
42.6
48.4
52.9
53.7
56.4
57.4
64.2
65.4
66.2
67.1
68.8
74.3
77.5
78.2
83.6
85.4
87.2
88.9
90.0
94.2
95.2
113.4
114.8
118.7
121.2
125.2
125.7
126.1
126.4
126.5
127.0
127.5
128.3
131.9
P32/M38-150
w-382bP37/M33-195
w-764w-661w-489bP35/M43-260
Lr16Lr16
P32/M35-125
BMP1
BMP1
w-264P38/M37-200
P38/M32-198
P34/M38-165
w-154P36/M33-148
P38/M37-100
barc318w-597cP36/M36-315
g-429aP33/M41-225
g-148aP37/M31-90
w-474g-403bg-271P32/M40-70
P37/M35-265
g-120ab-101aP34/M32-123
b-308aw-332P34/M42-135
P34/M39-60
P37/M41-90
P37/M31-175
P34/M35-175
P37/M41-300
P37/M39-195
w-317P36/M32-185
P32/M42-215
P36/M36-185
P33/M33-120
P34/M42-330
P34/M36-123
P34/M42-202
P38/M37-80
g-382a-
Fig. 2 Linkage group of chromosome 2B. In bold,
leaf rust resistance genes.
Fig. 1 a Linkage group of chromosome 6B and b linkage
groups of chromosome 2A. Dashed lines represents gaps
between linkage groups. Genetic distances in centimorgans
(cM) by Kosambi function. In bold, leaf rust resistance
genes.
Another race was used that identified the Lr13 gene for
adult plant resistance, but failed to show the presence of this
gene in the Buck Manantial in the present study. Further
analysis is being carried out to confirm the presence of
Lr13. The closely linked marker csLV34 (codominant
sequence tagged site, Lagudah et al, 2006) to Lr34 (located
on chromosome 7D) was used to detect the presence of this
resistance gene in Buck Manantial as hypothesized by Dyck
(1989). The presence of Lr34 could not be confirmed in
2
Fig. 3 PCR amplification of Buck Manantial (BM),
Purlpestraw (P) and the near isogenic Thatcher line
+ Lr34, using the csLV34 primers. M-100 bp ladder
molecular size markers. Amplification product of
230 bp is associated with lines that lack Lr34 and
the product of 150 bp is associated with wheat lines
that carry Lr34.
DISCUSSION
REFERENCES
The study of traditional wheat varieties from South
America showing durable resistance to leaf rust is of
great value, as they can provide new sources of
resistance to this disease. It is probable that in the
development of Buck Manantial seedling and adult
plant resistance genes of major effects have been
accumulated, so the pathogen population could not
overcome resistance in this wheat cultivar. It is of
interest to characterize resistance genes in Buck
Manantial and to have molecular markers linked to
these genes. In the present work three of the known
leaf rust resistance genes were mapped to their
respective chromosome arms and linked molecular
markers were found. In addition we could saturate
chromosome 2B (Fig. 2) with molecular markers that
should be valuable for linkage with Lr16, Lr13
(although not confirmed in this study) and the BMP1.
The order of SSRs and the length of the 2B was quite
similar to that determined by Somers et al, (2004) in a
consensus map of wheat.
It is striking to note that the highly effective resistance
to natural leaf rust infection conferred by Lr16, or the
complex of Lr16 together with BMP1 (if both genes
are alleles or a closely linked cluster needs a more
detailed study) was also shown by the cultivar
Americano 25e (Kolmer et al, 2007). In addition
Americano 25e carries Lr3 gene, one unidentified
seedling resistance gene and at least one APR gene.
Americano 25e is the ancestor of many early South
American wheats, including Buck Manantial.
There are still APR genes to be identified in Buck
Manantial, as suggested by the segregation for race 77,
in the RILs population. This race apparently identifies
2 epistatic genes (duplicate genes), approaching a 3:1
segregation. However, races that can separate both
genes are not available in our Institute. A future
experiment, using only susceptible families, which lack
seedling resistance genes, is underway to elucidate both
the presence of Lr13 gene as well as other unidentified
genes in Buck Manantial.
ACKNOWLEDGEMENTS
This work has been supported by grants from SECYT
(Secretaría de Ciencia y Técnica) and INTA (Instituto
Nacional de Tecnología Agropecuaria, Argentina). We
wish to thank to Lorena Ingala, Micaela Lopez, María
Fernanda Pergolesi and María Jose Dieguez from the
Instituto de Genética “E:Afavret” and to Barbara
Mulock, Pat Seto-Goh, Laura Trump, Yanfen Zheng,
Debbie Miranda and Zlatko Popovic from the Cereal
Research Centre.
Dieguez MJ, Altieri E, Ingala LR, Perera E,
Sacco F and Naranjo T, 2006. Physical
and genetic mapping of amplified
fragment length polymorphisms and the
leaf rust resistance Lr3 gene on
chromosome 6BL of wheat. Theor Appl
Genet. 112: 251-257.
Dyck PL, 1989. The inheritance of leaf rust
resistance in wheat cultivars Kenyon and
Buck Manantial. Can. J. Plant Sci. 69:
1113-1117.
Favret EA, Saione HA y Franzone PM, 1983.
New approaches in breeding for disease
resistance.
Cereak
breeding
and
production Symp. Argentina. Special
report 718. Oregon State University.
Kolmer JA, Oelke LM and Liu JQ, 2007.
Genetics of leaf rust resistance in three
Americano
landrace-derived
wheat
cultivars from Uruguay. Plant Breeding.
126: 152-157.
Lagudah ES, McFadden H, Singh RP, HuertaEspino J, Bariana HS, Spielmeyer W,
2006. Theor Appl Genet. 114: 21-30.
McCallum BD, Seto-Goh P, 2005. Physiologic
specialization of wheat leaf rust (Puccinia
triticina) in Canada in 2002. Can. J. Plant
pathol. 27: 90-99.
McIntosh RA, Wellings CR and Park RF,
1995. Wheat rusts: an atlas of resistance
genes. Ed. by McIntosh RA, Wellings CR
and Park RF. Kluwer Academic
publishers.
Roder MS, Korzum V, Wendehake K ç,
Plashke J, Tixier MH, Leroy P, Ganal
MW, 1998. A microsatellite map of
wheat. Genetics. 149: 2007-2023.
Saione HA, Favret EA, Franzone PM and
Sacco F, 1993. Host genetic analysis by
using Puccinia recondita tritici induced
mutants for increased virulence. J
Phytopathology. 138: 225-232.
Somers DJ, Isaac P, Edwards K, 2004. A highdensity microsatellite consensus map pf
bread wheat (Triticum aestivum L.) Theor
Appl Genet. 109: 1105-1114.
Vos P, Hogers R, Bleeker M, Reijans M, Van
de Lee T, Hornes M Fritjers A, Pot J,
Peleman J, Kuiper M and Zebeau M.
1995. AFLP: a new technique for DNA
fingerprinting. Nucleic Acids Res. 23:
4407-4414.
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