Brent Hulke, Thomas Gulya Jr. and Jinguo Hu
Abstract: Work was conducted in 2008 to determine the stalk rot resistance of RILs from the RHA 280 x RHA 801 population, as well as to begin introgression of previously identified QTL for head rot resistance into elite sunflower germplasm lines. The stalk rot RILs and their testcrosses with cms HA 89 were tested in two environments in 2008. Only one environment produced good differentiation of lines and testcrosses, the other was uninformative. This data, taken together with previous data from 2006 and the greenhouse, is not enough to release lines from this population. Analysis with molecular markers in this population has found six putative QTL for stalk rot resistance, although the stalk rot resistance data going into the model had a large error variance. The work to begin introgression of the head rot QTL into elite germplasm began this year with the final purification of a RIL line with a large number of the QTL alleles of interest, and the formation of F1 populations in both confection and oilseed backgrounds. As of December, work was underway to genotype the F1 plants and parent lines to confirm genomic constitution at the loci of interest, as well as to produce BC1F1 seed to continue population development. An additional backcross will be attempted in 2009, with line development and field testing to follow.
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