Gene Expression Changes in Root Tissues of Sweet Sorghum (Sorghum bicolor L. Moench) in Response to Waterlogging.

Abstract

Sweet sorghum (Sorghum bicolor L. Moench) is a promising bioenergy crop. Some of the attributes of sweet sorghum that suggest great potential include rapid growth and a short growing season, adaptation to water-scarce conditions, tolerance of low-fertility environments, as well as production of sugars that can be fermented without prior enzymatic treatment. Periodic short-term flooding can be quite common in low-lying areas, which may be used for production of sweet sorghum as a bioenergy feedstock, along rivers in the US Midwest. However, very little is known about sweet sorghum waterlogging tolerance and associated molecular mechanisms. Therefore, 200 sweet sorghum genotypes were evaluated for the response to waterlogging under field conditions. After the first year, the most tolerant and most susceptible genotypes were tested further under field and greenhouse conditions. Based on these results, two contrasting genotypes (tolerant vs susceptible) were selected to study gene expression responses in apical and basal root zones in response to waterlogging. Waterlogging and control conditions were imposed on 30 days old greenhouse-grown plants of the two genotypes. Tissue samples from the growth zone and basal region of nodal roots of waterlogged and control plants were sampled after 18 hours and after 4 days of waterlogging and used for RNA-seq analysis. Results of the differentially expressed genes (DEG) analyses will be presented and discussed. This study will provide new insight into sweet sorghum responses to waterlogging and candidate genes for the development of tolerant cultivars.

Key word: Sweet sorghum, Waterlogging, RNA-seq, Differentially expressed genes, Candidate genes.