Genome-wide identification and characterization of UGT family in pigeonpea (Cajanus cajan) and expression analysis in abiotic stress

Family 1 UDP-glycosyltransferases (UGTs; EC 2.4.1.x) are enzymes that glycosylate aglycones into glycoside-associated compounds. They play an important role in plant resistance to abiotic stresses by regulating the synthesis of plant hormones and secondary metabolites. However, in pigeonpea, the UGT family has not yet been reported. Here, 120 CcUGT genes were identified from the pigeonpea genome, which all contained the plant secondary product glycosyltransferase motif (PSPG). According to the phylogenetic relationship, 120 CcUGTs can be classified into 11 major groups. The CcUGTs are distributed on 10 chromosomes except chromosome 5. Homology modeling of CcUGT proteins and conserved motif search were used to predict the structure of 120 UGTs. Most protein structures can be predicted with high accuracy. After that, 11 representative CcUGT genes were selected for further analysis. We measured their specific expression in different tissues and the changes in transcription levels after stress. The results show that 11 genes are specific in different tissues and the expression of genes in leaves is higher than that of other tissues. In roots, CcUGT69 genes were highly expressed in salt and osmotic stresses, and CcUGT110 was up-regulated in low temperature injury. In leaves, most of the genes were up-regulated after stress treatment, and only CcUGT6, 37, 56 had little change in transcription levels. Overall, this study systematically analyses the UGT gene family in pigeonpea for the first time and provides some useful clues for further functional studies of UGT genes.