Location: Corn Insects and Crop Genetics Research2010 Annual Report
1a. Objectives (from AD-416)
Objective 1: Identify and utilize fertility/sterility mutants in a phenotypic recurrent selection program for insect-mediated cross-pollination to increase hybrid seed production. Objective 2: Identify phenotypes/genotypes that can be characterized and molecularly mapped that contribute to insect-pollinator attraction and reward.
1b. Approach (from AD-416)
Soybean accessions in the USDA germplasm collection will be crossed with known cytoplasmic restorer lines to identify cytoplasmic male sterile cytoplasms. Sterility mutants (nuclear) obtained via gene tagging from the w4-mutable system will be characterized genetically. Both the cytoplasmic and nuclear sterility mutants will be used in a phenotypic recurrent selection system, with insect-mediated cross-pollination, to increase hybrid seed production. The plant factors that contribute to the increased attraction/reward of the insect pollinators will be identified, characterized, and molecularly mapped.
3. Progress Report
Progress was made on all objectives and their sub-objectives. Progress was made on cytoplasmic male sterility (a type of plant sterility that would greatly enhance hybrid breeding in soybean) in the USDA-ARS soybean germplasm. In 2010, the search for maintainer and restorer soybean germplasm was initiated to preserve our supposed cytoplasmic male-sterile germplasm. Additional fertility/sterility mutants will be molecularly mapped. Plant structural and chemical traits associated with soybean insect-pollinator attraction and reward were identified and characterized at our Nebraska location. For the CRADA, they will identify and characterize traits that contribute to insect-mediated out-crossing, a postdoctoral candidate was identified and will begin work August 2010. Soybean accessions in the USDA germplasm collection were crossed with known cytoplasmic restorer lines to identify cytoplasmic male sterile germplasm. Sterility mutants will be characterized genetically. Cytoplasmic (or extra-nuclear) and nuclear sterility mutants will be used in a plant breeding system using generational selections that will take advantage of insect-mediated cross-pollination, to increase hybrid seed production.
1. Identification of soybean germplasm with supposed cytoplasmic male-sterility (CMS). Identification of soybean germplasm with cytoplasmic male-sterility will be useful to produce hybrid soybean seed commercially. No cytoplasmic male-sterility system has been documented within the USDA-ARS soybean germplasm based upon our cross-pollinations. Eight sterility mutants were mapped molecularly in soybean. The location of these sterility mutants expands our knowledge about the chromosomal distribution of sterility mutants. There are clusters of sterility mutants in certain chromosome regions. At present, the significance of this clustering is not known. The discovery and characterization of cytoplasmic male sterility and nuclear male sterility provides the genetic material to evaluate the possibility of commercializing hybrid soybean. Hybrid seed should enhance agronomic performance and result in increased seed yield, and hopefully increased profits.