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Title: Characterization of two adult-plant stripe rust resistance genes on chromosomes 3BS and 4BL in soft red winter wheat

Author
item SUBRAMANIAN, NITHYA - University Of Arkansas
item MASON, RICHARD - University Of Arkansas
item MILUS, EUGENE - University Of Arkansas
item MOON, DAVID - University Of Arkansas
item Brown-Guedira, Gina

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/1/2015
Publication Date: 11/23/2015
Citation: Subramanian, N.K., Mason, R.E., Milus, E.A., Moon, D.E., Brown Guedira, G.L. 2015. Characterization of two adult-plant stripe rust resistance genes on chromosomes 3BS and 4BL in soft red winter wheat. Crop Science. 56(1):143-153.

Interpretive Summary: Stripe rust is an important foliar disease of soft red winter wheat (SRWW) in the eastern U.S. However, very few resistance genes have been characterized in the SRWW germplasm pool. The SRWW line VA96W-270 is known to be resistant to stripe rust race PST-100, which was the predominant race in the U.S. from 2003 to 2006. To elucidate the genetic basis of resistance, a recombinant inbred line (RIL) population developed from a cross between VA96W-270 and the susceptible cultivar Coker 9835 was evaluated for response to stripe rust infection in inoculated field nurseries in Fayetteville, AR over a three-year period. The same population of lines was then genotyped with DNA markers. Two major genes were identified, located on wheat chromosomes 3BS and 4BL with both contributed by the VA96W-270 parent. The 3BS and 4BL genes explained up to 28% and 25% of the phenotypic variation for disease, respectively, and appear to be an important source of stripe rust resistance for soft red winter wheat. Lines containing both genes had average disease severity of 6%, compared to 38 to 45% for lines containing one of the two genes and 69% for those containing neither resistance gene. Based on susceptibility of VA96W-270 to stripe rust infection at the seedling stage, the two identified genes appear to be associated with adult-plant resistance. The markers associated with the two genes were polymorphic in various wheat genotypes, suggesting they could be useful in marker assisted selection (MAS) to develop wheat cultivars with improved stripe rust resistance.

Technical Abstract: Stripe rust, caused by Puccinia striiformis f. sp. tritici, is an important foliar disease of soft red winter wheat (SRWW) in the eastern U.S. However, very few resistance genes have been characterized in the SRWW germplasm pool. The SRWW line VA96W-270 is known to be resistant to stripe rust race PST-100, which was the predominant race in the U.S. from 2003 to 2006. To elucidate the genetic basis of resistance, a recombinant inbred line (RIL) population developed from a cross between VA96W-270 and the susceptible cultivar Coker 9835 was evaluated for response to stripe rust infection in inoculated field nurseries in Fayetteville, AR over a three-year period. Disease severity scores were used to calculate area under the disease progress curve (AUDPC). Following parental screening with simple sequence repeat (SSR) markers, a bulked segregant analysis was performed on resistant and susceptible bulks each consisting of five lines. The RIL population was then genotyped with stripe rust-linked SSR markers and 90K single nucleotide polymorphism (SNP) markers. Two major QTL were identified, located on chromosomes 3BS and 4BL with both contributed by the VA96W-270 parent. The 3BS and 4BL QTL explained up to 28% and 25% of the phenotypic variation for AUDPC, respectively, and appear to be an important source of stripe rust resistance for soft red winter wheat. RILs containing both QTL had average disease severity of 6%, compared to 38 to 45% for lines containing one of the two QTL and 69% for those containing neither QTL. Based on susceptibility of VA96W-270 to stripe rust infection at the seedling stage, the two identified genes appear to be associated with adult-plant resistance. The markers associated with the two QTL were polymorphic in various wheat genotypes, suggesting they could be useful in marker assisted selection (MAS) to develop wheat cultivars with improved stripe rust resistance.