Functional Genomic Analyses Reveal Molecular Systems Underlying Chilling Response in Cold-tolerant and Cold-susceptible Sorghums

Tropical crops are extremely sensitive to low temperatures, which is a limiting factor for their cultivation in temperate regions. To understand the molecular basis of chilling adaptation in sorghum, transcriptome and lipidome analyses were conducted on the chilling-tolerant Chinese accession Niu Sheng Zui (NSZ) and chilling-susceptible US accession BTx623 subjected to optimal temperature and chilling stress individually. During chilling stress, upregulation of cold-response regulator CBF/DREB (C-repeat binding factor/dehydration responsive element binding) transcription factor and genes involved in ROS detoxification, jasmonic acid (JA) biosynthesis, lipid reorganization is observed in NSZ compared to BTx623. The lipidome analysis revealed alterations in galactolipids, phospholipids and higher storage lipids (triacylglycerols) in NSZ during chilling. These two functional genomics approaches suggest lipid remodeling mediated JA signaling may lead to activation of CBFs, which possibly activates downstream cold regulated (COR) genes to provide chilling tolerance in sorghum. Upregulation of JA, CBFs and COR genes could a mechanism of chilling adaptation in Chinese sorghums. The functional genomics data obtained from our research can aid in developing early-season chilling tolerance in tropical crops.