The cotton gene family encoding translationally controlled tumor proteins and the role of GhTCTP5 in salt tolerance.

Translationally controlled tumor proteins (TCTPs) are highly conserved proteins found in virtually all eukaryotes, and their expression is intricately linked with numerous biochemical processes and cellular activities. However, intriguingly, within the realm of key cash crops, investigations of the TCTP gene in cotton are relatively limited. This study sought to elucidate the evolutionary relationships and structural functions of the TCTP gene in cotton with a whole-genome analysis approach. Within Gossypium arboreum (G. arboreum), Gossypium raimondii (G. raimondii), Gossypium barbadense (G. barbadense), and Gossypium hirsutum (G. hirsutum), we found three, three, six, and five TCTP domain sequences, respectively. A detailed examination of their genetic architecture and evolutionary history revealed a strikingly conserved progression among TCTP family members. Notably, segmental duplications emerged as a pivotal mechanism in the expansion of the cotton TCTP family, with virtually no evidence of tandem duplications. The assessment of the cis-acting elements within the TCTP gene promoters suggested that these genes might be influenced by plant hormones and various environmental stresses. By applying virus-induced gene silencing (VIGS) and RNA-seq, we determined that GhTCTP5 plays a critical role. Specifically, the response of cotton to salt stress is most likely regulated by its participation in the phenylpropanoid metabolic synthesis pathway, which adds to our understanding of its functional complexity. These results provide insights for understanding the evolution of TCTP genes in cotton, thus establishing a robust foundation for the subsequent exploitation of these genes to increase crop salt tolerance.