Description

A poster presented at the 2012 Global Pulse Researchers Meeting, Kigali, Rwanda- “Transforming Grain-Legume Systems to Enhance Nutrition and Livelihoods”. Abstract: Dry bean genotypes with increased efficiency for biological nitrogen fixation (BNF) are sought for improving dry bean production on low fertility soils. Our Goal is to identify QTL and candidate genes which condition increased BNF in dry bean leading to improved breeding strategies. BNF capacity is difficult to measure phenotypically and molecular markers offer the potential to improve screening for this trait. Our first objectives was to characterize genotypic variability for BNF capacity in bean lines that are parents of existing recombinant inbred line populations. Approximately 50 dry bean genotypes have been screened for BNF capacity measured in terms of plant biomass and nitrogen levels when grown under low N conditions. One line with exceptional BNF capacity, Puebla 152, has been used in bi-parental crosses with commercially acceptable black, pinto, and great northern beans. These populations are being advanced. In addition, to better understand the variability for BNF in African germplasm an association mapping population comprised of about 300 dry bean accessions of Andean origin will be genotyped with 6000 SNPs and phenotyped for BNF ability in field and greenhouse screens. A third strategy is to investigate RNA expression levels in contrasting genotypes for candidate genes for BNF capacity. These include genes in the de-novo purine biosynthesis pathway which are precursors of ureide biosynthesis. These strategies for identifying QTL and genes for BNF in dry bean will be elucidated and preliminary results reported.