Download Citrus Virus Diseases

Citrus Virus
Diseases
Bill Dawson
All graft-transmissible diseases initially were considered to be caused by viruses
Examples of changes
•Viroids
citrus exocortis
cachexia
xyloporosis
•Phytoplasmas, Spiroplasmas
stubborn
new phytoplasma in Brazil that causes greening symptoms
•Bacteria
greening
citrus varigated chlorosis
http://www.apsnet.org/online/common/names/citrus.asp
VIRAL DISEASES
Citrus mosaic
Satsuma dwarf-related virus
Bud union crease
Virus for some combinations, otherwise genetic or unknown
Citrus leaf rugose
genus Ilarvirus, Citrus leaf rugose virus (CLRV)
Citrus yellow mosaic
genus Badnavirus
Crinkly leaf
Crinkly leaf ilarvirus (strain of citrus variegation virus)
Infectious variegation
genus Ilarvirus, Citrus variegation virus (CVV)
Navel infectious mottling
Satsuma dwarf-related virus
Psorosis
Spirovirus (ophiovirus) proposed new group
Satsuma dwarf
Satsuma dwarf virus (SDV)
Tatter leaf = citrange stunt
genus Capillovirus, Citrus tatter leaf virus (probably a closely related strain of apple stem
grooving capillovirus rather than a distinct virus
Tristeza = decline and stem pitting, seedling yellows
genus Closterovirus, Citrus tristeza virus (CTV)
VIROIDS AND GRAFT-TRANSMISSIBLE PATHOGENS (GTP)
Algerian navel orange virus
Impietratura
GTP
GTP
Blight = young tree decline, rough lemon decline
Indian citrus ringspot
GTP
GTP
Blind pocket
Leaf curl
GTP
GTP
Cachexia
Leathery leaf
Citrus cachexia viroid (Hostuviroid)
GTP
Chlorotic dwarf
Leprosis
White-fly transmitted GTP
GTP associated with Brevipalpus spp. mites
Citrus dwarfing
Measls
Varios viroids
GTP
Citrus yellow mottle
Milam stem-pitting
GTP
GTP
Citrus yellow ringspot
Multiple sprouting disease
GTP
GTP
Concave gum
Nagami kumquat disease
GTP
GTP
Cristacortis
Ringspot diseases
GTP
Various GTPs
Exocortis
Vein enation = woody gall
Citrus exocortis viroid (CEVd) (Pospiviroid)
GTP (possible luteovirus)
Fatal yellows
Xyloporosis = cachexia
GTP
Citrus cachexia viroid (Hostuviroid)
Gummy bark
Yellow vein
GTP, possible viroid
GTP
Gum pocket and gummy pittings
Yellow vein clearing of lemon
GTP, possible viroid
GTP
Edited by
J.O. Whiteside, S.M. Garnsey, and L.W. Timmer
APS Press
The American Phytopathological Society
1988
Endemic Viruses of Concern
•Tatterleaf / Citrange Stunt
•Infectious Variegation
•Citrus Leaf Rugose
•Psorosis complex
•Citrus leaf blotch
•Citrus tristeza decline
Tatter Leaf and Citrange Stunt virus complex
latent infections in Meyer lemons
apparently wide spread in China
•Host Range and Symptoms
when infected cultivars are propagated on trifoliate or hybrids (Swingle
citrumelo, Carrizo, Troyer, and Kuharske citrange), trees are
stunted and chlorotic, virus-induced incompability
can infect a wide range of citrus cultivars
causes mild symptoms if not on trifoliate rootstock
can infect a wild range of herbaceous hosts
Tatter Leaf and Citrange Stunt virus complex continued
•Causal Agent
one positive-sense RNA
two subgenomic RNAs
CP
ORF 1
A(n)
ORF 2
A(n)
A(n)
•Transmission and Epidemiology
graft transmitted by infected budwood
mechanically transmitted to a range of hosts
thought to be aphid transmitted?
•Identification
characteristic bud union creasing
symptoms on herbaceous hosts
•Control
virus-free budwood, difficult to remove
decontaminate tools, knives
use rootstocks other than Poncirus hybrids
Wild type virus infected (8 dpi)
Wild type virus infected (15 dpi)
Healthy
Infectious Variegation – Citrus Variegation Virus (CVV)
•Host Range and Symptoms
can infect most citrus species
lemons, sour orange, citron, and grapefruit develop chlorotic leaf symptoms
and distortion
mild strains exist that cause only mild mottle or chlorotic flecking
trees can be stunted, some fruit may be distorted
symptoms are less in warm weather
can be mechanically transmitted to some cowpeas (chlorotic or necrotic
lesions and beans (chlorotic mottle or veinbanding)
Infectious Variegation – Citrus Variegation Virus (CVV) continued
•Causal Agent
ilarvirus – 4 positive-sense RNAs, sperical particles
Citrus crinkly leaf virus is a mild variant
•Transmission and Epidemiology
grafting – budwood
mechanically inoculate
seed transmitted – apparently rare
pollen transmission?
•Identification
indexing by graft inoculation to lemon or citron
mechanical inoculation to cowpea or bean
•Control
infected budwood can be freed by thermotherapy or shoot tip grafting
then use virus-free budwood
Leaf Rugose – Citrus leaf rugose virus (CLRV)
•Host Range and Symptoms
infects a broad range of citrus hosts
Mexican lime, Eureka lemon, and Duncan grapefruit develop leaf puckering,
pinpoint chlorotic spotting, and stunting
can be mechanically transmitted to a range of noncitrus hosts
Leaf Rugose – Citrus leaf rugose virus (CLRV) continued
•Causal agent
ilarvirus – 4 positive-sense RNAs, isometric particles
•Transmission and Epidemiology
grafting and mechanical transmission
no vector known, but get some local spread
pollen?
•Identification
indexing by grafting Eureka lemon or bush bean
serology
•Control
use virus-free budwood
decontamination of pruning tools
Psorosis (psorosis A, mild; psorosis B, severe; concave gum; )
probably a complex of several diseases, which share common symptoms
usually found present in old-line trees
often bark scaling
•Host Range and Symptoms
symptoms stronger on young leaves ranging from chlorotic flecks, to leaf
mottling and chlorotic patterns
scaling and flaking of bark on the trunk and limbs of sweet orange and
grapefruit and occasionally mandarins -- usually not on other citrus
wood becomes impregnated with gum
concave gum thought to be related, mandarins and sweet oranges are
affected, deep concavities in the trunk and main branches
Concave Gum
Psorosis
Psorosis (psorosis A, mild; psorosis B, severe) continued
•Causal Agent
•Transmission and Epidemiology
graft transmitted
seed transmission rare
apparently some unknown vector
•Identification
field symptoms of bark scaling
indexing by grafting to sweet orange or mandarin seedlings for leaf-flecking
•Control
use virus-free budwood, use seed only from virus-free trees
can use shoot-tip grafting or thermotherapy
decontaminate tools
Citrus ringspot virus (CRSV) – Psorosis B
•Host Range and Symptoms
irregular spots or large, irregular chlorotic patterns on mature leaves
frequently gum impregnated and are slightly raised on the lower surface
fruit may have ringspots
some isolates are mechanically transmitted to Chenopodium spp
Citrus ringspot virus (CRSV) – Psorosis B continued
•Causal Agent
ophiovirus, 3 negative-sense RNAs
very thin thread-like particles
next slide has genome description
•Transmission and Epidemiology
graft transmissible
mechanical transmissible
vector suspected but unknown
•Control
virus-free budwood
decontamination of tools
The complete nucleotide sequence of a Spanish
isolate
of Citrus psorosis virus: comparative analysis
with other ophioviruses
Brief Report
S. Mart´ın1, C. L´opez2, M. L. Garc´ıa3, G. NaumOngan´ıa3,
O. Grau3, R. Flores2, P. Moreno1, and J. Guerri1
Arch Virol (2005) 150: 167–176
Association of citrus psorosis B symptoms
with a sequence variant of the Citrus
psorosis virus RNA 2 Velazquez, K
(Velazquez, K.)1; Pina, JA (Pina, J. A.)1;
Navarro, L (Navarro, L.)1; Moreno, P
(Moreno, P.)1; Guerri, J (Guerri, J.) PLANT
PATHOLOGY 61: 448-456
The virus induces two different syndromes: psorosis A (PsA), characterized by limited bark scaling
lesions in the trunk and main limbs, and a more aggressive form of the disease called psorosis B (PsB)
with rampant bark lesions affecting even thin branches and chlorotic blotches in old leaves. In the
greenhouse, the PsA and PsB syndromes can be induced by graft inoculating healthy citrus seedlings
with non-lesion or with lesion bark inoculum from PsA-affected field trees. PsA- and PsB-inducing
CPsV sub-isolates obtained by this procedure from the same tree showed segments of the RNA 2
enabled discrimination between PsA- and PsB-associated sequence variants. (i) PsA-inducing isolates
contain PsB-associated sequence variants at low frequency, (ii) the PsB-associated sequence variant
is predominant in blistered twigs and gummy pustules affecting old leaves, characteristic of PsB
isolates, and (iii) the PsB-associated sequence variant accumulates preferentially in bark lesions of the
trunk and limbs.
Citrus leaf blotch virus (CLBV)
•Host Range and Symptoms
first found in kumquat on Troyer citrange rootstock with bud union
crease
Spain, France, Japan, Australia, Florida
associated with abnormal bud unions on poncirus hybrid rootstocks
•Causal Agent
filamentous particles
one positive-stranded RNA with 2 subgenomics
p41
p227
p40
Poly-A
Poly-A
•Transmission and Epidemiology
no known vector
seed transmitted
•Control
virus-free budwood
alternative rootstocks if necessary
Poly-A
Citrus tristeza virus
Causes four disease syndromes:
decline – only on sour orange rootstocks
can be quick decline – can be slow
seedling yellows -- usually seen in greenhouse
on sour orange and grapefruit
no disease – mild strains
stem pitting – on all rootstocks
Department of Plant Industry
Budwood certification
Dr. Peggy Sieburth
Winter Haven
Budwood trees tested:
Citrus tristeza virus decline isolate (MCA-13 positive) tested yearly
OK to have budwood with the mild isolate of CTV
Psorosis and Concave gum tested once by biological indexing
now starting to test every 6 years
Citrus leaf blotch virus (Dweet mottle virus) once every 6 years in budwood
source trees and also in seed source trees since it is seed
transmitted
Citrus tatter leaf virus will start test for next year
Infectious variegation virus is not tested for because it is mainly a problem for
lemons which are limited in Florida
Also test for viroids I, II, III, IV, V, and CEV every 6 years
EXOTIC
VIRUSES
Exotic Viruses of Concern
•
•
•
•
•
•
•
Citrus chlorotic dwarf (CCD)
Citrus yellow mosaic
Leprosis
Satsuma Dwarf
Tristeza stem pitting
Vein enation
Sudden death
Vein Enation (Woody Gall)
important commercially only when severe galling occurs on young
trees budded to rough lemon rootstocks
•Host Range and Symptoms
enations on the veins of Mexican lime, sour orange, and rough lemon
swelling or galls on the stems of rough lemon and Mexican lime
Vein Enation (Woody Gall) continued
•Casual Agent
spherical viruslike particles
•Transmission
grafting
aphid transmitted – Myzus persicae, Toxoptera, citricida, and Aphis
gossipii
not mechanically transmitted
•Control
clean budwood
avoid use of rough lemon rootstocks
Leprosis and Zonate Chlorosis
•Host Range and Symptoms
observed primarily on sweet orange
sour orange and mandarins are also show symptoms
other citrus normally do not show symptoms
symptoms are chlorotic lesions, sometimes with a necrotic center
later lesions become flat or raised necrotic areas
leaves and fruit abscise when lesions are abundant, can get twig dieback
can mechanically transmit to Chenopodium spp
Leprosis
Leprosis and Zonate Chlorosis continued
•Causal Agent
controversy – may be two different viruses causing similar diseases
rare nuclear form that is rod shaped and more prevalent cytoplasmic form of
baciliform particles– would be expected to be a rhabdovirus
positive-sense RNA virus with 2 RNAs
virus is a mite virus – Brevipalpus spp. – virus multiplies in mites
•Transmission and Epidemiology
transmitted by mites -- millions of individual infections
graft transmitted with difficulty
virus does not move long distances, systemically
•Control
eliminate sources of inoculum
control mites, acaricides to reduce mite population
Satsuma dwarf virus (SDV)
•Host Range and Symptoms
wide host range in citrus
widely spread in Japan
stunting and narrow, boat- or spoon-shaped leaves in satsuma mandarin
Chenopodium, cowpea, bean, Physalis, Gomphrena
Satsuma dwarf virus (SDV) continued
•Causal Agent
small isometric virus with 2 RNAs
genome on next slide
•Transmission and Epidemiology
graft transmitted by infected budwood
mechanically transmitted to herbaceous hosts
local spread, maybe a soilborne vector
•Control
virus-free budwood
Nucleotide sequences and taxonomy of satsuma dwarf virus
Toru Iwanami,1 Yoshiko Kondo1 and Alexander V. Karasev2
J Gen Virol. 1999 Mar;80 ( Pt 3):793-7.
Citrus Sudden Death
new disease reported in Brazil in 1999
•Host Range and Symptoms
decline disease limited to Rangpur lime and to limited extent on
Volkamer lemon during periods of drought
rapid death of trees during drought
characteristic yellow stain at or below the bud union
Citrus Sudden Death -- continued
•Causal Agent
some controversy, a sobemovirus-like, marafivirus
but CTV association
genome on next slide
• Transmission and Epidemiology
spread looks similar to aphid transmission of CTV
no vector identified
can be grafted?
•Identification
decline – determine whether on Rangpur lime or Volkamer lemon
yellow stain at graft union
•Control
virus-free budwood
irrigation
inarching
Identification and Genomic Characterization of a New Virus (Tymoviridae Family) Associated with Citrus Sudden Death
Disease
Walter Maccheroni,1 Marcos C. Alegria,1 Christian C. Greggio,1 João Paulo Piazza,1 Rachel F. Kamla,1 Paula R. A. Zacharias,1 Moshe Bar-Joseph,1,
Elliot W. Kitajima,2 Laura C. Assumpção,1 Giovana Camarotte,1 Jussara Cardozo,1 Elaine C. Casagrande,1 Fernanda Ferrari,1 Sulamita F. Franco,1
Poliana F. Giachetto,1 Alessandra Girasol,1 Hamilton Jordão Jr.,1 Vitor H. A. Silva,1 Leonardo C. A. Souza,1 Carlos I. Aguilar-Vildoso,1 Almir S. Zanca,1
Paulo Arruda,1 João Paulo Kitajima,1 Fernando C. Reinach,1 Jesus A. Ferro,1 and Ana C. R. da Silva1*
J Virol. 2005 Mar;79(5):3028-37.
Citrus Sudden Death
inarching
Citrus yellow mosaic virus
India, perhaps Japan
•Host Range and Symptoms
mosaic of leaves
does not reduce fruit production, but fruit have less juice and ascorbic
acid
wide citrus host range but apparently does not infect Mexican lime
Citrus yellow mosaic virus
•Causal Agent
badnavirus – double-stranded circular DNA virus
•Transmission and Epidemiology
mechanically transmitted
transmitted by aphids or mealybugs?
Citrus chlorotic dwarf virus (CCD)
found in Turkey
•Host Range and Symptoms
causes crinkled and puckered leaves in lemon, tangelo, and sweet
orange
•Transmission and Epidemiology
transmitted by the bayberry whitefly Parabemisia myricae
grafting of infected budwood
mechanically transmitted
•Identification
can do greenhouse experiments, but no simple identification
•Control
CCD in lemon
CCD in mandarin
CCD in grapefruit
Identification of a single-stranded DNA virus associated with citrus chlorotic
dwarf disease, a new member in the family Geminiviridae
Giuliana Loconsolea, Pasquale Saldarellib, Harshavardhan
Doddapanenic, Vito Savinoa, b, Giovanni P. Martellia, b, Maria Saponarib,
Virology 432: 162-172 (2012)
Citrus Tristeza Virus (CTV) – Decline
•Host Range and Symptoms
can infect most citrus varieties and relatives
Poncirus spp are resistant to most isolates
disease is limited to scions on sour orange rootstocks
Roots of declining tree – no feeder roots
Citrus tristeza virus – decline
•Causal Agent
positive-stranded RNA virus ~ 20,000 nts
RdRp
PRO PRO MT
p6
p61
p18
p20
HEL
p33
HSP70
p27 CP
p13
p23
Gold-labeled CP
antiserum
Gold-labeled CPm
antiserum
CTV virions
From: Tian et al. J. Gen.
Virol.80:1111 (1999)
p27 (minor capsid protein, CPm)
p25 (major capsid protein, CP)
Citrus tristeza virus
ORF
1a
1b
2 3
4
5
6
p33 HSP70h
PRO PRO
MT
7 8 9 10 11
CPm
p18 p20
HEL
IDR
5’ probe
3’ probe
RdRp
Polyprotein: Replicase
p6
(
p61
CP p13 p23
)
()
(
)
(
)
(
+1 Ribosomal frameshift: RdRp
)
(
)
(
)
(
)
(
)
(
Proteins
)
p33
p6
HSP70h
p61
CPm
CP
p18
p13
p20
p23
Citrus tristeza virus (CTV) – decline
•Transmission and Epidemiology
aphid transmitted by a series of aphids, brown citrus aphid best
also melon, cotton aphids
transmitted in a semi-persistent manner – ~ 1 hr to ~ 24 hr
•Identification
in field, identify rootstock – sour orange
bud union staining, scion overgrowth, thickened bark at union
serology – can detect CTV; can differentiate FL mild from decline
biological assay in greenhouse
vein clearing and leaf cupping in Mexican lime
•Control
use alternative rootstock
use virus-free or decline-free budwood
Citrus tristeza virus (CTV) – stem pitting
no severe stem pitting isolates of CTV known to be in Florida
every effort is being made to keep them out
•Host Range and Symptoms
stem pitting does not kill trees
reduces vigor, reduces growth, reduces yield and fruit size
stem pitting is specific to virus isolate and host
some isolates cause stem pitting in grapefruit
some isolates cause stem pitting in sweet orange
some isolates cause stem pitting in both
mandarins are more tolerant
•Control
keep stem pitting isolates out
mild strain cross protection
FS674
on DG
Risk evaluation of exotic pathogens for citrus
Disease
Impact
Intro
Estab
Spread
Estab m
Estab F
Detection
Control
factor 1
factor 2
HLB
10
7
7.1
7
7.03
347.90
2.6
10
1828.7
90454.0
100.00%
100.00%
Blackspot
5.8
6.2
8.7
10
8.30
539.40
3.3
6.9
1096.1
71236.4
59.94%
78.75%
CTV-SP
6.1
5.8
9.8
9.1
8.23
517.24
2.5
5.5
690.6
43383.8
37.76%
47.96%
Canker
7.9
10
7.7
10
9.23
770.00
1
3.5
255.3
21290.5
13.96%
23.54%
7
4.1
10
7.8
7.30
319.80
0.9
8.4
386.3
16923.8
21.13%
18.71%
Phaeoram
5.2
3.2
6.8
9.3
6.43
202.37
2
7.2
481.7
15153.3
26.34%
16.75%
CCD
1.9
2.9
5.1
4.3
4.10
63.60
10
7.1
553.1
8579.2
30.24%
9.48%
Leprosis
2.4
4.2
3.8
3.6
3.87
57.46
4
3.5
129.9
1930.5
7.10%
2.13%
Swt. Scab
1.2
2.7
4.7
4.7
4.03
59.64
1.6
3.2
24.8
366.4
1.36%
0.41%
Vein Enation
0.2
3.1
4.7
7.9
5.23
115.10
2.5
3.6
9.4
207.2
0.52%
0.23%
SDV
0.8
2.6
4.1
3.8
3.50
40.51
1.2
4.8
16.1
186.7
0.88%
0.21%
CYM
1.9
2.1
4.1
3.1
3.10
26.69
1
2.6
15.3
131.9
0.84%
0.15%
ACD
0.2
1.3
2.1
2.4
1.93
6.55
9
8.9
31.0
105.0
1.69%
0.12%
Stubborn
1
4.2
2.1
3.8
3.37
33.52
0.6
4.9
9.9
98.5
0.54%
0.11%
Pow. Mil
0.6
1.3
2.3
4
2.53
11.96
0.8
2.7
3.3
15.5
0.18%
0.02%
LWB
0.7
1.3
1.8
1.9
1.67
4.45
1.7
1.9
3.8
10.1
0.21%
0.01%
Mal Secco
0.4
2.1
1.1
1.8
1.67
4.16
1.3
1.5
1.3
3.2
0.07%
0.00%
CVC
4factRel %
6factRel%
Mild strain cross protection
Purposely inoculate trees with a mild strain of the virus to prevent infection by
severe stem pitting isolate
Common practice in Brazil, South Africa, Australia
How does cross protection work?
different strains of CTV do not cross protect against each other
must find a mild strain that has close sequence to the severe strain
otherwise must make one
CTV-based expression vector
ORF
L1
1a
1b
2
3
p33
L2
MT
IDR
4
5
HSP70h
6
7
CPm
8
9 10 11
p18
p20
HEL
RdRp
p6
p61
CP
p13
p23
Green fluorescent protein
from jellyfish
L1
p33
L2
MT
IDR
gfp
HSP70h
p18
p20
HEL
RdRp
p6
p61
CPm
CP
p13
p23
DIFFERENTIAL SUSCEPTIBILITY OF DIFFERENT HOSTS TO T36
ML
CM
MV
SO
DG
1 mm
C mac
So Orange
No protection against GFP-expressing T36 strain-based virus:
T68-1
T3
T30
VT
T36
Protection
FS 703 protection
FS672 challenge
No protection
FS672 challenge
FS 703 protection
FS701 challenge
No protection
FS701 challenge
What about CTV decline?
•Have to have a mild isolate of the T36 strain
•Probably does not exist in Florida
•Then have to make one
Florida CTV strains
PRO PRO MT
decline
RdRp
p6
p61
HEL
p33 HSP70
PRO PRO MT
mild
p18 p20
RdRp
p6
p27 CP p13
p61
p23
p18 p20
HEL
p33 HSP70
p27 CP p13
p23
Genetic system for CTV
cDNA
Healthy seedling
CTV Infected
tree
dsRNA
Bacteria
Virus particles
in vitro transcription
Protoplast
virus
RNA
Healthy
Seedling yellows reaction
on sour orange plants
rCTV-T36
WT CTV-T36
T36/T30 hybrids
p33
HSP70h
CPm
p18
p20
3’
RdRp
p6
p33
p61
HSP70h
CP
CPm
p13
p18
p23
p20
3’
RdRp
p6
p33
p61
HSP70h
CP
CPm
p13
p23
p20
p18
3’
RdRp
p6
p33
p61
HSP70h
CP
CPm
p13
p23
p20
p18
3’
RdRp
p6
p33
p61
HSP70h
CP
p13
p20
p18
CPm
p23
3’
RdRp
p6
p33
p61
HSP70h
CP
CPm
p13
p18
p23
p20
3’
RdRp
p6
p61
CP
p13
p23
PRO PRO MT
decline
RdRp
p6
p61
PRO PRO MT
RdRp
p6
p27 CP p13
p61
hybrid
*
+
p23
p18 p20
HEL
p33 HSP70
PRO PRO MT
p18 p20
HEL
p33 HSP70
mild
SY
RdRp
p6
p27 CP p13
p61
p23
p18 p20
HEL
p33 HSP70
p27 CP p13
p23
Healthy
T30
T36
P23+NTR of
T30 in T36
Sour Orange
P65+p61 of T30
Substitution of p23 gene + NTR of T30 into genome of T36 creates
cross-protecting isolate against seedling yellows
T36-infected sour orange
Healthy sour orange
In the center – p23+NTR-T30/T36 hybrid-infected sour orange, later challenged with T36
field test to protect citrus
on sour orange rootstocks