microRNA and Gene Regulatory Networks Governing Soybean Nodule Development

Lateral roots and nodules are root lateral organs produced by leguminous plants. Unlike shoot lateral organs, lateral roots and nodules are formed away from the root apical meristem via de novo differentiation. While commonalities in some developmental features led to the speculation that nodules might have adopted the developmental pathways of lateral roots, hormonal requirement of these organs are rather distinct. We evaluated global transcriptome profiles of soybean lateral roots and nodules at two distinct stages of development. We observed distinct enrichment of transcription factors, and hormone biosynthesis and signaling components. Specifically, we observed distinct enrichment of auxin and cytokinin biosynthesis and signaling components in lateral root and nodule tissues respectively. Functional evaluation indicated that a regulatory module consisting of miR160 directed developmental stage specific auxin-cytokinin balance during nodule development. Application of two different network inference algorithms into one ensemble solution identified seven highly confident GRN modules of co-regulated genes potentially involved in nodule development in soybean. Results from functional analysis and network prediction will be presented and discussed.