Naturally colored cotton (NCC; Gossypium spp.) does not require additional chemical dyeing and is an environmentally friendly textile material with great research potential and applications. Our previous study using linkage and association mapping identified TRANSPARENT TESTA 2 (Gh_TT2) as acting on the proanthocyanin synthesis pathway. However, limited information is available about the genetic regulatory network of NCC. Here, we verified the effectiveness of Gh_TT2 and the roles of Gh_TT2 and red foliated mutant gene (Re) in pigment formation and deposition of brown fiber cotton (BFC). Variations in Gh_TT2 derived from interspecific hybridization between Gossypium barbadense acc. Pima 90-53 and Gossypium hirsutum acc. Handan208 resulted in gene expression differences, thereby causing phenotypic variation. Additionally, the MYB-bHLH-WD complex was found to be negatively modulated by TRANSPARENT TESTA 16/ARABIDOPSIS BSISTER (TT16/ABS). RNA-seq suggested that differential expression of homologous genes of key enzymes in the proanthocyanin synthesis pathway strongly contributes to the color rendering of natural dark brown and light brown cotton. Our study proposes a regulatory model in BFC, which will provide theoretical guidance for the genetic improvement of NCC.

中文翻译：

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透明 TESTA 16 与 MYB-bHLH-WD40 转录复合物合作生产棕色纤维棉


天然色棉 （NCC;棉属）不需要额外的化学染色，是一种具有巨大研究潜力和应用的环保纺织材料。我们之前使用连锁和关联图谱的研究确定 TRANSPARENT TESTA 2 （Gh_TT2） 作用于原花青素合成途径。然而，关于 NCC 遗传调控网络的信息有限。在这里，我们验证了 Gh_TT2 的有效性以及 Gh_TT2 和红色叶状突变基因 （Re） 在棕色纤维棉 （BFC） 色素形成和沉积中的作用。Gh_TT2 来源于 Gossypium barbadense acc. 之间的种间杂交的变异。Pima 90-53 和 Gossypium hirsutum acc.Handan208 导致基因表达差异，从而引起表型变异。此外，发现 MYB-bHLH-WD 复合物受到 TRANSPARENT TESTA 16/ARABIDOPSIS BSISTER （TT16/ABS） 的负调控。RNA-seq 表明，原花青素合成途径中关键酶同源基因的差异表达强烈促进了天然深棕色和浅棕色棉花的显色性。本研究提出了一种 BFC 调控模型，将为 NCC 的遗传改良提供理论指导。