1a.Objectives (from AD-416):
The objective of the project is to transfer an identified gene for rust (Puccinia helianthi) resistance into an acceptable confectionery sunflower genetic background and make it available to the private seed industry for incorporation into finished commercial hybrids.
1b.Approach (from AD-416):
Three known rust resistance genes, R2, R5, and Radv, will be introduced into suitable confectionery sunflower inbred lines. Sunflower line CM29 containing the R2 gene will be crossed with inbred line CONFSCL B1; line HAR-2 containing the R5 gene will also be crossed with inbred line CONFSCL B1; and line RHA 340 containing the Radv gene will be crossed with line CONFSCL R5. Both the CONFSCL B1 and CONFSCL R5 lines are confectionery sunflower inbred lines with resistance to Sclerotinia disease. The progeny of these crosses will be planted for further backcrossing in the summer 2010 season. The goal for the first year of this projected three-year project is to have the BC1 (first backcross generation) available for planting in the greenhouse in the winter of 2010-11 for production of the BC2 (second backcross generation). At each generation, the progeny will be screened for rust resistance. This should allow the development of pure inbred lines with rust resistance after only a few generations, and the lines can be released to the sunflower seed industry by 2012.
The goal of the proposed project is to transfer rust resistant genes (R2, R4, and R5) into confection sunflower breeding material, pyramid these genes with a new rust resistance gene in HA-R6 and create plants with more broad-spectrum and long-lasting resistance features. To date we have obtained the homozygous BC3F4 and BC4F4 plants harboring the rust resistance genes R5 and R4 in confection sunflower background, respectively. These homozygous plants were confirmed by progeny rust test and DNA marker test and are ready to be released. We developed DNA markers linked to rust resistance genes R13a in HA-R6 and R13b in RHA 397. In our gene pyramiding project, we screened a total of 368 F2 plants from the cross between an R5 line and an R13a line using DNA markers linked to them, and obtained 13 F2 plants with the combination of R5 and R13a at the homozygous state. These double-resistant F2 plants were grown in the field to advance to F3 generation.