Gene coexpression analysis identifies genes associated with chlorophyll content and relative water content in pearl millet

Pearl millet is a significant crop tolerant to abiotic stresses and is a staple food of arid regions. However, its underlying mechanisms of stress tolerance is not fully understood. Plant survival is regulated by the ability to perceive a stress signal and induce appropriate physiological changes. Here, we screened for genes regulating physiological changes such as chlorophyll content (CC) and relative water content (RWC) in response to abiotic stress. Using weighted gene co-expression network analysis (WGCNA) and clustering associated changes in physiological traits, i.e., CC and RWC with gene expression. A group of genes showing correlation with traits was identified as modules, and different color names were used to denote a particular module. In WGCNA, the darkgreen module (7082 genes) showed a significant positive correlation with CC, and the black (1393 genes) module was negatively correlated with CC and RWC. Analysis of the module positively correlated with CC highlighted ribosome synthesis and plant hormone signaling as the most significant pathways. Potassium transporter 8 and monothiol glutaredoxin were reported as the topmost hub genes in the darkgreen module. In Clust analysis, 2987 genes were found to display a correlation with increasing CC and RWC. Further, the pathway analysis of these clusters identified ribosome and thermogenesis as positive regulators of RWC and CC, respectively. Our study provides novel insights into the molecular mechanisms regulating CC and RWC in pearl millet.