Graduate Research Assistant University of Florida GAINESVILLE, Florida
Body of Abstract: Since the Green Revolution, the extensive use of synthetic fertilizers has been the most common strategy to alleviate the limitation of nitrogen availability on crop yields. Synthetic fertilizer production negatively impacts the environment, economic costs, and the environmental footprint of bioenergy crops. Sorghum is an attractive bioenergy crop due to its ability to produce high biomass yields with minimal inputs ,while also withstanding biotic and abiotic stresses. Select sorghum accessions form mucilage-producing aerial roots – adventitious roots that are formed from stem nodes and do not touch the soil – that harbor nitrogen-fixing bacteria enabling biological nitrogen fixation (BNF). A genome-wide association study (GWAS) employing two genetically diverse panels, the sorghum minicore (235 landraces) and the sorghum association panel (338 modern cultivars), detected two loci that appear to be associated with the number of nodes forming aerial roots linked to genes encoding transcription factors. The effect of nitrogen fertilization level and location (Florida vs. Wisconsin) on aerial root formation were evaluated with an analysis of variance (ANOVA), indicating that genotype and environment influence aerial root production. In parallel, we have developed an F2 population of bioenergy sorghums that produce aerial roots to evaluate the mode of inheritance and validate the loci identified by the GWAS. This F2 population is also used for the selection of nitrogen-fixing bioenergy sorghums that display high biomass yields on marginal lands, with minimal inputs. Furthermore, we propose transgenic experiments with the detected loci to gain a more comprehensive understanding of the molecular mechanisms underlying BNF in sorghum.