Unveiling kiwifruit TCP genes: evolution, functions, and expression insights

The <i>TEOSINTE-BRANCHED1/CYCLOIDEA/PROLEFERATING-CELL-FACTORS</i> (TCP) gene family is a plant-specific transcriptional factor family involved in leaf morphogenesis and senescence, lateral branching, hormone crosstalk, and stress responses. To date, a systematic study on the identification and characterization of the <i>TCP</i> gene family in kiwifruit has not been reported. Additionally, the function of kiwifruit TCPs in regulating kiwifruit responses to the ethylene treatment and bacterial canker disease pathogen (<i>Pseudomonas syringae</i> pv. <i>actinidiae</i>, Psa) has not been investigated. Here, we identified 40 and 26 <i>TCP</i> genes in <i>Actinidia chinensis</i> (Ac) and <i>A. eriantha</i> (Ae) genomes, respectively. The synteny analysis of <i>AcTCPs</i> illustrated that whole-genome duplication accounted for the expansion of the <i>TCP</i> family in Ac. Phylogenetic, conserved domain, and selection pressure analysis indicated that <i>TCP</i> family genes in Ac and Ae had undergone different evolutionary patterns after whole-genome duplication (WGD) events, causing differences in <i>TCP</i> gene number and distribution. Our results also suggested that protein structure and <i>cis</i>-element architecture in promoter regions of TCP genes have driven the function divergence of duplicated gene pairs. Three and four <i>AcTCP</i> genes significantly affected kiwifruit responses to the ethylene treatment and Psa invasion, respectively. Our results provided insight into general characters, evolutionary patterns, and functional diversity of kiwifruit <i>TCPs</i>.