Project Number: 5442-21000-034-03
Project Type: Specific Cooperative Agreement

Start Date: Aug 12, 2005
End Date: Jun 30, 2009

Objective:
1. To identify sunflower wild species with resistance to Sclerotinia; 2. Develop Sclerotinia resistance germplasm by incorporating resistant genes from wild species into cultivated background.

Approach:
Twenty wild sunflower accessions of H. maximiliani and H. nuttallii previously identified as having Sclerotinia resistance will be reevaluated, and the resistant accessions crossed with cultivated inbred lines. Embryo rescue will be utilized to establish all the F1 hybrids. Seedlings will be treated with colchicine to induce chromosome doubling and to produce amphiploids. Amphiploids will be evaluated for Sclerotinia head rot resistance by artificial inoculation with ascospores and growth under mist irrigation to optimize environmental conditions. Similar procedures will be followed for the stalk rot resistance gene transfer. Evaluations will be made with inoculum consisting of Sclerotinia mycelium grown on millet grains, which are then deposited in the soil beside each plant in the field, and below the plant roots for greenhouse pots.