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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 #338613
Title: Genotyping-by-sequencing targeting of a novel downy mildew resistance gene Pl20 from wild Helianthus argophyllus for sunflower (Helianthus annuus L.)

Author
item MA, GUOJIA - North Dakota State University
item MARKELL, SAM - North Dakota State University
item Song, Qijian
item Qi, Lili

Submitted to: Theoretical and Applied Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/7/2017
Publication Date: 4/21/2017
Citation: Ma, G.J., Markell, S.G., Song, Q.J., Qi, L.L. 2017. Genotyping-by-sequencing targeting of a novel downy mildew resistance gene Pl20 from wild Helianthus argophyllus for sunflower (Helianthus annuus L.). Theoretical and Applied Genetics. 130(7):1519-1529.

Interpretive Summary: Global sunflower production is plagued by many diseases among them downy mildew (DM) being one of the most destructive. Current management tools include removing volunteer sunflower plants that serve as a host, fungicides applied as seed treatments, and planting DM-resistant hybrids; the latter being the most economically and environmentally-friendly tool. New races of DM are continually emerging rendering the current resistant sunflower hybrids ineffective necessitating the search for new resistance sources. A new source of resistance was discovered in a wild annual silver leaf sunflower from Texas. It is highly effective against the most predominant and virulent races of downy mildew currently identified in North America. Resistance is controlled by a single dominant gene, named Pl20, making it easier to transfer into cultivated sunflower. The molecular markers for the novel gene were identified that can be used in sunflower breeding programs. The discovery of a new source of resistance to DM will provide a more efficient, durable, and environmentally friendly host plant resistance to sustain sunflower as economically viable crop.

Technical Abstract: Downy mildew (DM) caused by Plasmopara halstedii is one of the most destructive diseases in the world that severely impacts sunflower production. Management tools for DM include the destruction of volunteer sunflower plants, fungicides applied as seed treatments, and planting DM-resistant hybrids; the latter being the most economically and environmentally-friendly tool. New DM races are continually emerging due to the co-evolution of plant hosts and pathogens, rendering the current resistant sunflower hybrids ineffective. There is a continuing need to expand and diversify the DM resistance gene pool for cultivated hybrid sunflower breeding efforts. DM resistance was identified in wild Helianthus argophyllus accession PI 494578 (silver leaf sunflower). Phenotypic analysis of the BC1F2:3 population revealed that a single dominant gene, Pl20, controls DM resistance. Genotyping-by-sequencing (GBS) analysis conducted in the BC1F2 population indicated that the Pl20 gene derived from the wild H. argophyllus was located on the linkage group 8 of the sunflower genome and co-segregated with four single nucleoid polymorphism markers. The new gene is highly effective against the most predominant and virulent races of downy mildew currently identified in North America. Resistant germplasm with the Pl20 gene developed in the present study provides a novel gene for use in sunflower breeding programs.