Correlation of bacterial leaf blight symptoms with presence of Sr2

Bob BowdenSeifollah P. KianiEduard Akhunov

Yr Mist Chamber Conditions

10-15°C, 100% relative humidity for 14-16 hours

Symptoms From Yr Mist Chamber

Bacterial Leaf Blight caused by Pseudomonas syringae pv. syringae

Photo by Bill Willis, KSU

Crosses for BLB Mapping

• Jagger/Thunder CL, n=295, F5 RILs• KS84HW196/Jagger, n=190, F5 RILs

PBC and SM Ratings

0 = no melanism 1 = low; few tillers have mild symptoms2 = moderate; many tillers have mild to

moderate symptoms3 = strong; most tillers have moderate

to strong symptoms

Association Mapping of PBC and SM

Correlation CoefficientsPBC SM BLB

PBC 1.00 0.72*** 0.39***

SM 0.72*** 1.00 0.53***

BLB 0.39*** 0.53*** 1.00

Sr2 STM559(Hayden et al, 2004)

0.49*** 0.44*** 0.29***

Sr2 csSr2(Mago et al, 2010)

0.66*** 0.48*** 0.18*

* p<0.01** p<0.001*** p<0.0001N=221 or 222

Lines with PBC, SM, and BLB• Arlin• Bennett• C004393• Erhardt• KS84HW196• Snowmass• Thunder CL• Wendy

• 2174• Avalanche• BondCL• Centerfield• OK05303• OK04507• OK04415• OK04111• OK06318• HV9W03-1551WP• HV9W03-1596R• MTS0713• Sturdy2K• TAM302

csSr2 (+) csSr2 (-)

SM, PBC, and BLBon 2174

Inoculations for S. nodorum

Summary

• Certain varieties develop symptoms similar to BLB when placed in a dew chamber overnight.

• Inoculation with P. syringae is not required.• BLB-like symptom scores correlate with PBC and SM

scores as well as Sr2 markers• Some Oklahoma varieties like 2174 seem to express

low to moderate BLB, PBC, and SM, but do not carry the diagnostic allele for csSr2 marker (Mago et al, 2010)

• A gene conferring susceptibility to BLB-like lesions appears to be linked to Sr2 on chromosome arm 3BS.