Post on 11-May-2015
description
Sources of Resistance to Stripe Rust in Synthetic Hexaploid Wheat
Habte-Mariam Z., A.Badebo and W. Denbel
K. Nazari, O.Francis
EIAR
Stripe/yellow rust
Caused by Puccinia striiformis
Major wheat disease in the temperate regions as well as in the highlands of the tropics and subtropics
Stripe rust in Ethiopia
Reported in 1947
Increased its importance since the late 1970s
Occurs regularly in the highlands >2400masl
Yield loss is severe (58%-96%) when spikes are infected
Importance
Stripe rust in Ethiopia…
In 1970s, on variety, “Laketch”- (Kalyansona ‘S’)
In 1988, on variety, “Dashen” (VEE’S’)
In 2010, on major varieties, including “ Kubsa” (Attila’S’) and “Galema” (4777(2)//FKN/GB/3/PVN’S’)
Major Epidemics
Stripe rust races
Monitored 1973-2003
1973-1992 in IPO, The Netherlands
1998-2003Goettingen/Kulumsa
(6E16) Yr 6, 7, 8
(38E16) Yr6, 7, 8, SD
(38E150) Yr6, 7, 8, SD,6+,7+, 2+
(166E150) Yr6, 7, 8, SD,6+, 7+, 2+ , 9+
(166E158) Yr6, 7, 8, SD, 6+, 7+, 2
+, 9+ , 3N
(230E158)Yr6, 7, 8, SD,
6+, 7+, 2+ , 9+, 3N, SU
(70E16)Yr6,7, 8, SU
(70E150)Yr6,7,6+, 7+, 8, SU, 2+
(82E16)Yr7, 9,10, SU 8
(82E0)
Yr7, 9, 10, SU
(86E0)Yr 7, 9,10, SU, 6
(6E6)Yr6,7, 6+,7+
(70E30)Yr6,7, 8, SU,3N, 6+, 7+
(78E30)Yr6,7, 8, SU,3N, 6+, 7+, 3V
(78E158)Yr6,7, 8, SU,3N, 6+, 7+ 3V, 2+
(206E158)Yr6,7, 8, SU,3N, 6+, 7+, 3V, 2+,
9+
(198E158)Yr6,7,6+, 7+, 8, SU, 2+,3N, 9+
Evolution of YR races in Ethiopia, 1973-2003 (Badebo et al., 2008)
Cultivar Race166E150 – V Dashen
230E150 -V Wabe
230E158 –V Kubsa
Dashen (Vee’s’) + + +
Wabe (MRL’S’/BUC’S’)
- + +
Kubsa (Attia’S’) - - +
Dominant races 1998-2003 in Ethiopia
All the commercial bread wheat succumbed to the ‘Kubsa’ race (230E158) at seedling tests in 1998 (Badebo et al., 2008)
Stripe rust races..
Most of the cultivated bread wheat varieties are susceptible to the prevailing races of stripe rust
Only a few Yr genes are effective: Yr 1 (Chinese 166), Yr4 (Hybrid 46), Yr5 (T.spelta album), Yr17 (Vpm), Yr15 (T. dicoccoides G-25), Yr SP and Yr32 (CV)
Stripe rust Resistance
Searching for new sources of resistance
Landraces
Primitive cultivars - center of diversity
Wild or semi-wild materials- Center of origin
Related mostly wild species
Where to look for?
The objective of this study was to identify new sources of stripe rust resistance in synthetic hexaploid wheat derived from Triticum durum and Aegilops tauschii
Objective
Materials and Method
Planting materials
A total of 764. synthetic hexaploid wheat derived from Aegilops tauschii and Triticum durum and developed in CIMMYT, Australia and ICARDA
Seedling test
Seedling test was carried out in the greenhouse at ICARDA using a local race of P. striiformis virulent on Yr2, Yr6, Yr7, Yr9, YrA, Yr25 and Yr27 genes, 2010
The field test was conducted at two locations in Ethiopia and at Tel-Hadya, Syria in 2010
In Syria, the nursery was planted at Tel-Hadya, ICARDA pathology plot, and evaluated under artificial inoculation
In Ethiopia, the nursery was planted at two locations (Meraro- ca. 2920 masl and Kulumsa-2200 masl) and evaluated under natural epidemics
Field test
Disease assessment
In seedling test, a 0 to 4 scale was used (McIntosh et al., 1995), and IT, 0-2 was considered as resistant and 3-4 as susceptible
In adult plant test, a modified Cobb’s scale was used for severity (%), for infection types (R, MR, MS and S) according Roelfs et al. (1992)
The field severity data were converted to CI by multiplying with constant numbers (R=0.2, MR=0.4, M=0.6, MS=0.8 and S=1) (Stubbs et al., 1986).
The SHWs were categorized into different resistance classes based on the CI values of the check cultivars
Results and DiscussionThere was high pressure of stripe rust both in Syria and Ethiopia in 2010
In Ethiopia, the disease appeared unusually early in the season in Arsi zone
Stripe rust epidemics
The epidemics covered almost all wheat growing regions except in Tigray
Most of the commercial bread wheat cultivars were susceptible
Durum wheat varieties were resistant
Increased in aggressiveness of the existing race (s) reported elsewhere (Milus et al., 2009) ?
New race (s) ? Mono-cropping/buildup of spore load?
Climate change ?
What are the possible causes?
0.020.040.060.080.0
100.0120.0140.0160.0
JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC0.0
50.0100.0150.0200.0250.0300.0
2001-09 (mean)2010
Bekoji, 2870
Kulumsa, 2200masl
Monthly rainfall (mm)distribution
Monthly Minimum Temperature (oC)
Kulumsa
0.0
2.0
4.0
6.0
8.0
10.0
12.0
JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC0.0
2.0
4.0
6.0
8.0
10.0
12.02001-09 2010Bekoji
Challenges and opportunities?
Screening of synthetic hexaploid wheat to stripe rust
Variety Severity CI Value Resistant Group
Kubsa 100S 100 S
Galama 100S 100 S
ET13-A2 3OMS 24 MS
K6295-4A 20MS 16 MR
Kenya Kudu 1oMS 8 R
Meraro 0 0 R
The reaction of check varieties to stripe rust at Meraro, 2010
Field test
The highest disease scores were noted at Meraro followed by Tel-Hadya.
0
20
40
60
80 73.6
11.4 7.1 6.7 1.2
01020304050
21
7.6 11.918.6
40.9
Meraro, N=754
R MR MS MSS S0
10203040 34.3
5.6 7.1
18.6
34.4Tel-Hadya, N=749
Kulumsa , N= 764
Frequency (%) of SHWs under different stripe rust reaction classes at three locations in Ethiopia and Syria, 2010
R MR MS MSS S0
10
20
30
40
50
60
12.1
4.6
10
21.2
52
Frequency (%) of SHWs under different resistance groups at adult plant growth stage across locations
Ethiopia + Syria, N=651
Seedling test
Out of 644 SHWs evaluated, 36.8 % exhibited resistance whereas the rest 63.2% were susceptible at seedling stage
SS/AS SS/AMSS SS/AMS SS/ARMR
SR/ARMR
SR/AMS SR/AMSS SR/AS0
5
10
15
20
25
30
35
40
45
N= 644
SR+ARMR, 11.8%SS+ARMR, 3.3%
Frequency (%) of SHWs under different reaction classes after being tested both at seedling and adult plant growth stage at Tel-Hadya, 2010
Summary and Conclusion
A total of 173 SHWs were identified as Resistant (78), Moderately Resistant (30), and Moderately susceptible (65) Out of these, about 20 % exhibited stem rust resistance (R- MS) including to Ug99 race at Debre Zeit, Ethiopia (Data not included).
In addition, some of the resistant SHWs in this study has been reported to be resistant to the Ethiopian and European (Badebo and Fehrman, 2005)
Based on the results, the SHWs are potential sources of resistance to stripe rust which should be exploited in wheat breeding program.
EIAR in collaboration with ICARDA, have initiated crosses to introgress resistance into adapted cultivars.
Summary and Conclusion…