Teosinte branched1/cycloidea/proliferating cell factor1 (TCP) is a plant-specific protein family member involved in plant growth and development. However, the functions of most members of the cotton TCP family are unknown. In this study, the GbTCP5 gene encodes a sea-island cotton class II TCP CIN subclass transcription factor. The GbTCP5 transcription factor is located in the nucleus, has transcriptional activation activity, and can bind to TCP II cis-acting elements. GbTCP5 was widely expressed in tissues with the highest transcript level in the calyx. GbTCP5 is expressed at different developmental stages of the fiber and has significantly high transcriptional level expression in the fibers at 20, 30 and 35 days post anthesis (DPA). Heterologous overexpression of the GbTCP5 gene increased root hair length, root hair and stem trichome density, and stem lignin content in transgenic Arabidopsis compared to the wild type (WT). GbTCP5 binds the promoters of the GL3, EGL3, CPC, MYB46, LBD30, CesA4, VND7, CCOMT1, and CAD5 genes to upregulate their expression. Moreover, the homologous genes of these genes are expressed in the fibers of different developmental stages of the sea-island cotton fiber. These results indicate that GbTCP5 regulates root hair development and secondary wall formation in Arabidopsis and may be a candidate gene for improving cotton fiber quality.

Teosinte branched1 / cycloidea / proliferating cell factor1（TCP）是涉及植物生长和发育的植物特异性蛋白质家族成员。但是，棉TCP系列大多数成员的功能尚不清楚。在这项研究中，GbTCP5基因编码一个海岛棉II类TCP CIN亚类转录因子。GbTCP5转录因子位于细胞核中，具有转录激活活性，可以与TCP II顺式作用元件结合。GbTCP5在花萼中转录水平最高的组织中广泛表达。千兆TCP5在花粉的20、30和35天后（DPA），在纤维的不同发育阶段中表达了α-β-糖蛋白，并且在纤维中具有显着高的转录水平表达。与野生型（WT）相比，GbTCP5基因的异源过表达增加了转基因拟南芥中的根毛长度，根毛和茎毛毛密度以及茎木质素含量。GbTCP5结合的发起人GL3，EGL3，CPC，MYB46，LBD30，CesA4，VND7，CCOMT1和CAD5基因上调其表达。而且，这些基因的同源基因在海岛棉纤维的不同发育阶段的纤维中表达。这些结果表明，GbTCP5调节拟南芥中根毛的发育和次生壁的形成，并且可能是改善棉纤维质量的候选基因。