Identification and expression analysis of the IGT gene family in Brassica rapa

The IGT gene family regulates the branching angle of plants and is important for plant yield, biomass, and ornamental effects. In this study, we analyzed the physicochemical properties, chromosomal localization, subcellular localization prediction, evolutionary relationship, cis-element prediction, covariance, and expression pattern of the IGT gene family at the genome-wide level based on the genome sequence information of Brassica rapa and Arabidopsis thaliana. A total of 11 IGT genes were identified in B. rapa, which were classified into seven branches, each of which comprised similar conserved motifs. Chromosomal localization and covariance analyses indicated that the chromosomes of the family members did not experience any significant changes during hybridization and polyploidization and that fragment duplication and homologous copying might be the primary modes of their expansion. Light-responsive elements predominated in most IGT promoters, followed by abscisic acid- and methyl jasmonate-responsive elements, indicating that the IGT promoter may be inducible. Transcriptome analysis revealed that the IGT genes of B. rapa had different expression patterns in different tissues (callus, flowers, leaves, roots, siliques, and stems); in particular, the TAC1 gene (BraIGT-11) had a higher expression level in flowers, followed by leaves and stems, suggesting that TAC1 may be important in regulating other aspects such as branching angle and flower development. In summary, this study provides a theoretical basis for the subsequent study of BraIGT gene function and provides a reference for breeding ideal plant types and the molecular breeding of B. rapa.