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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 #331085
Title: Discovery and introgression of the wild sunflower-derived novel downy mildew resistance gene Pl19 in confection sunflower (Helianthus annuus L.)

Author
item ZHANG, ZHIWEI - Inner Mongolian Agriculture University
item MA, GUOJIA - North Dakota State University
item ZHAO, JUN - Inner Mongolian Agriculture University
item MARKELL, SAM - North Dakota State University
item Qi, Lili

Submitted to: Theoretical and Applied Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/30/2016
Publication Date: 1/1/2017
Citation: Zhang, Z.W., Ma, G.J., Zhao, J., Markell, S.G., Qi, L.L. 2017. Discovery and introgression of the wild sunflower-derived novel downy mildew resistance gene Pl19 in confection sunflower (Helianthus annuus L.). Theoretical and Applied Genetics. 130:29-39.

Interpretive Summary: Downy mildew (DM) caused by Plasmopara halstedii is one of the most destructive diseases to sunflower production in the world. Historically, host genetic resistance has provided an economically and environmentally friendly method for controlling downy mildew. However, the main drawback of using resistance genes to control disease is that their effects are often not durable given the rapid evolution of DM pathogen. This limitation necessitates the continued search for new sources of resistance and the design of new strategies for more durable resistance. Wild sunflower species are an important source of downy mildew resistance genes. A wild Helianthus annuus accession PI 435414 exhibits resistance to downy mildew. This resistance was introduced into confection sunflower. Genetic analysis indicated that a single dominant gene, named Pl19 controls downy mildew resistance in the mapping population. Pl19 is located on linkage group 4 of the sunflower genome and is flanked by two single nucleoid polymorphism (SNP) markers, NSA_003564 and NSA_006089 at 0.6 cM from each side, which is well suitable for marker-assisted selection in molecular breeding. This new gene is highly effective against the most predominant and virulent races of downy mildew currently identified in North America. The developed resistant germplasm in this study provides a novel gene for use in confection sunflower breeding programs.

Technical Abstract: Wild Helianthus annuus accession PI 435414 exhibited resistance to downy mildew, which is one of the most destructive diseases to sunflower production globally. Evaluation of the 140 BC1F2:3 families derived from the cross of CMS CONFSCLB1 and PI 435414 against Plasmopara halstedii race 734 revealed that a single dominant gene controls downy mildew resistance in the population. Bulked segregant analysis conducted in the BC1F2 population with 860 simple sequence repeat (SSR) markers indicated that the resistance derived from wild H. annuus was associated with SSR markers located on linkage group (LG) 4 of the sunflower genome. To map and tag this resistance locus, designated Pl19, 140 BC1F2 individuals were used to construct a linkage map of the gene region. Two SSR markers, ORS963 and HT298, were linked to Pl19 within a distance of 4.7 cM. After screening 27 additional single nucleotide polymorphism (SNP) markers previously mapped to this region, two flanking SNP markers, NSA_003564 and NSA_006089, were identified as surrounding the Pl19 gene at a distance of 0.6 cM from each side. Genetic analysis indicated that Pl19 is different from Pl17, which had previously been mapped to LG4, but is closely linked to Pl17. This new gene is highly effective against the most predominant and virulent races of P. halstedii currently identified in North America and is the first downy mildew resistance gene that has been transferred to confection sunflower. The selected resistant germplasm derived from homozygous BC2F3 progeny provides a novel gene for use in confection sunflower breeding programs.