Li Gong, Sam Markell, Brandy Vick, Brent Hulke, Thomas Gulya Jr and Lili Qi
Abstract: Sunflower rust (Puccinia helianthi) emerged as a serious disease in the last few years. Confection sunflower is particularly vulnerable to the disease due to the lack of resistance sources. The objectives of this project are to transfer rust resistance genes from oil sunflower to confectionery sunflower and to molecularly mark the rust resistance genes. After screening the resistance of a total of 104 entries to rust race 336 (the predominant race in North America) and race 777 (the most virulent race currently known), we selected three oil sunflower inbred lines, MC29 (R2 gene), HA-R3 (R4), and HA-R2 (R5) as resistance gene donors. Two USDA recently released confection inbred lines, CONFSCL B1 and CONFSCL R5, served as recurrent parents. The BC3F1 will be obtained in the spring of 2011. The identified molecular markers linked to R2, R4, and R5 genes will facilitate the rust resistance gene introgression. Four other inbred lines, HA-R6, HA-R8, RHA397, and RHA464, were identified to resist both rust races 336 and 777. They were crossed with HA89 (a highly rust susceptible type) to create four F2 populations for mapping these new rust resistance genes. Eight hundred seventy previously mapped SSR markers showed approximately 50% polymorphism among each of the four lines with HA89. F2:3 families (twenty plants for each family) derived from the cross of HA89 and RHA 464 were tested for their reaction to rust race 336 in greenhouse trials to confirm the phenotype and assign the genotype of the F2 plants.
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