Genome-Wide Identification and Analysis of BrTCP Transcription Factor Family Genes Involved in Cold Stress Tolerance in Winter Rapeseed (Brassica rapa L.)

TCP transcription factors are important during plant growth and stress responses. However, their role in the cold stress response of <i>Brassica rapa</i> L. remains poorly understood. In this research, we identified the <i>TCPs</i> gene family in <i>B. rapa</i> to learn the features of the <i>BrTCP</i> gene family, functionally annotating the interacting proteins of TCP4 and analyzing their expression levels. Our results illustrated the presence of 19 members of the <i>BrTCPs</i> family in <i>B. rapa</i>, exhibiting molecular weights ranging from 27,367.45 to 59,433.64 Da. All identified proteins were classified as unstable, with isoelectric points ranging from 5.5 to 9.48. Subcellular localization forecasted that TCP proteins were all positioned in the nucleus. The <i>BrTCP</i> gene structure is relatively simple, with only seven members possessing introns, and none of the members contain UTR regions. <i>BrTCPs</i> comprise hormone-, light-, and stress-responsive elements. We found that the frequency of photoresponsive elements was greatest in the promoter region, suggesting that <i>BrTCP</i> genes are regulated by light signals and function synergistically with plant growth and development. In addition, five candidate interaction proteins of <i>BrTCP4</i> were identified using yeast two-hybrid screening. RNA-Seq and q-PCR analyses of the interacting genes revealed differential expression of <i>BrTCP</i> family genes across various tissues following cold stress. Significant responses were observed under low-temperature stress, drought stress, and rehydration treatment, suggesting that these genes play crucial roles as regulators of the molecular network mechanisms responding to stress. This study enhances our understanding of the <i>BrTCP</i> family and provides significant insights into the stress tolerance mechanisms of <i>B. rapa.</i>