Assistant Professor of Practice University of Nebraska-Lincoln
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Sorghum [Sorghum bicolor L. Moench] exhibits greater tolerance of heat and drought than its close relative, maize, allowing it to thrive in marginal land with fewer inputs. As a result, sorghum plays an important role in the agricultural economy of the arid west in the United States, and a critical role in food security in Africa and South Asia. While maize and sorghum are close relatives they exhibit divergent inflorescence (flowering structure) morphology. The morphology of both sorghum panicles and maize ears contributes to a number of important yield component traits in each species, while selection for higher yield in maize may also have selected for reductions in tassel size and/or branch number. Previous studies that have examined genes controlling variation in sorghum inflorescence architecture has focused primary on gross traits including inflorescence length, inflorescence width, rachis length, number of nodes, and branch length. Variation in these aggregate traits results from phenotypic variation in other more specific characteristics of the sorghum inflorescence. We phenotyped ten inflorescence architecture traits across the diverse lines of the Sorghum Association Panel (SAP), over two separate field seasons. Genome-wide Association Studies identified statistically significant trait associated SNPs for each of the ten traits scored. Some of these SNPs are linked to loci that are homologous to characterized loci known to control inflorescence architecture (e.g. Ra2 and Apo1) in other plant species, including maize. Other significant SNPs are linked to loci shown previously to be important determinants of plant height and maturity in sorghum (e.g. Dw2 and Ma1). Currently, functional validation is being pursued for key candidate genes in sorghum, as well as syntenic orthologous genes in maize, through plant transformation using CRISPR/Cas9.
