Abstract：
The monotonicity of color type in naturally colored cottons (NCCs) has become the main limiting factor to their widespread use, simultaneously coexisting with poor fiber quality. The synchronous improvement of fiber quality and color become more urgent and crucial as the demand for sustainable development increases. The homologous gene of wild cotton Gossypium stocksii LAC15 in G. hirsutum, GhLAC15, was also dominantly expressed in the developing fibers of brown cotton XC20 from 5 DPA (day post anthesis) to 25 DPA, especially at the secondary cell wall thickening stage (20 DPA and 25 DPA). In XC20 plants with downregulated GhLAC15 (GhLAC15i), a remarkable reduction in proanthocyanidins (PAs) and lignin contents was observed. Some of the key genes in the phenylpropane and flavonoid biosynthesis pathway were down-regulated in GhLAC15i plants. Notably, the fiber length of GhLAC15i plants showed an obvious increase and the fiber color was lightened. Moreover, we found that the thickness of cotton fiber cell wall was decreased in GhLAC15i plants and the fiber surface became smoother compared to that of WT. Taken together, this study revealed that GhLAC15 played an important role in PAs and lignin biosynthesis in naturally colored cotton fibers. It might mediate fiber color and fiber quality by catalyzing PAs oxidation and lignin polymerization, ultimately regulating fiber colouration and development.
摘要：
自然色棉(NCC)颜色类型的单调性已经成为其广泛应用的主要限制因素,同时共存，纤维质量差。随着可持续发展需求的增加，纤维质量和颜色的同步改善变得更加紧迫和关键。陆地棉野生棉花LAC15的同源基因，GhLAC15在棕色棉XC20从5DPA（花后日）到25DPA的发育纤维中也主要表达，特别是在次生细胞壁增厚阶段（20DPA和25DPA）。在具有下调的GhLAC15（GhLAC15i）的XC20植物中，观察到原花青素（PAs）和木质素含量显着降低。在GhLAC15i植物中，苯丙烷和类黄酮生物合成途径中的一些关键基因被下调。值得注意的是,GhLAC15i植株的纤维长度明显增加，纤维颜色变浅。此外，我们发现，与WT相比，GhLAC15i植物的棉纤维细胞壁厚度减少，纤维表面变得更光滑。一起来看,这项研究表明，GhLAC15在天然有色棉纤维中的PAs和木质素生物合成中起重要作用。它可能通过催化PAs氧化和木质素聚合来调节纤维颜色和纤维质量，最终调节纤维的着色和发展。
