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ARS Home » Plains Area » Fargo, North Dakota » Edward T. Schafer Agricultural Research Center » Sunflower and Plant Biology Research » Research » Publications at this Location » Publication #314974
Title: Map saturation and SNP marker development for the rust resistance genes (R4, R5, R13a, and R13b) in sunflower (Helianthus annuus L.)

Author
item Qi, Lili
item LONG, YUNMING - North Dakota State University
item MA, GUOJIA - North Dakota State University
item MARKELL, SAME - North Dakota State University

Submitted to: Molecular Breeding
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/10/2015
Publication Date: 10/7/2015
Citation: Qi, L.L., Long, Y.M., Ma, G.J., Markell, S.G. 2015. Map saturation and SNP marker development for the rust resistance genes (R4, R5, R13a, and R13b) in sunflower (Helianthus annuus L.). Molecular Breeding. 35:196.

Interpretive Summary: Sunflower rust is the most common disease in Australia, Argentina, South Africa, and North America. Yield losses to rust can be very high and are closely related to increasing disease severity. In epidemic scenarios, up to 80% losses have been reported in North America. While yield losses to rust can be mitigated with fungicide applications, genetic resistance is a more economically and environmentally desirable management tool. The objective of this study was to develop molecular markers linked to three independent genes, R5, R4, and R13 with two alleles R13a and R13b discovered in sunflower that are promising sources of resistance to rust. The genotyping of the mapping populations with these genes resulted in the identification of molecular markers tightly linked to the genes. To increase durability of the rust resistance genes, an confection sunflower carrying the rust gene R5 was crossed with confection sunflower carrying genes R13a creating a “double-resistant” population. Markers for these rust genes will facilitate markers-assisted selection in sunflower breeding programs. The double-resistant line developed in this study will provide a source of durable resistance to manage rust in confection sunflower and will help mitigate selection pressure on the genes by the pathogen.

Technical Abstract: Sunflower rust, which is incited by the fungus Puccinia helianthi Schwein., is the most common disease in Australia, Argentina, South Africa, and North America. Three independent genes, R5, R4, and R13 with two alleles R13a and R13b, were discovered in sunflower and are promising sources of resistance to rust. R5 was previously mapped to linkage group (LG) 2, and R4 and R13 were mapped to LG13 of the sunflower genome using simple sequence repeat (SSR) markers. The objective of this study was to finely map R5, R4, R13a, and R13b using newly developed single nucleotide polymorphism (SNP) markers in four F2 populations previously used for SSR mapping. Of the 67 LG2 SNP markers screened, two SNPs, SFW03654 and NSA_000267, flanked R5 at a genetic distance of 0.6 cM and 1.2 cM, respectively. This flanking narrowed the genetic interval containing R5 from 5.1 to 1.8 cM in length. A total of 69 LG13 SNP markers were analyzed in the R4, R13a, and R13b populations. In the R4 consensus map, the gene R4 was flanked by seven SNP loci; three co-segregating SNPs are on one side (0.7 cM proximal) and four on the other side (0.6 cM distal). Similarly, SNP markers that are tightly linked to both R13a and R13b were identified. R13a was flanked by SNP markers at genetic distances of 0.4 and 0.2 cM. The SNP SFW00757 was co-segregated with R13b, and another three co-segregating SNPs were 2.4 cM proximal to R13b. A total of 368 F2 plants from the cross between a resistant BC3F2 plant carrying R5 with HA-R6 carrying R13a were first screened by SSR markers to identify “double-resistant” lines. Twelve F2 plants were identified to be homozygous for a combination of R5 and R13a, which was further confirmed with additional SNP markers developed in the present study. The double-resistant line developed in this study may provide a source of durable resistance to manage rust in confection sunflower production and will help mitigate selection pressure on each gene by the pathogen.