College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, 430000, Hubei, China.
National Key Laboratory of Cotton Bio-Breeding and Integrated Utilization, Institute of Cotton Research, Chinese Academy of Agricultural Sciences, Anyang, 455000, Henan, China.
Plant J. 2024 Feb;117(3):694-712. doi: 10.1111/tpj.16523. Epub 2023 Nov 21.
Xyloglucan, an important hemicellulose, plays a crucial role in maintaining cell wall structure and cell elongation. However, the effects of xyloglucan on cotton fiber development are not well understood. GhMUR3 encodes a xyloglucan galactosyltransferase that is essential for xyloglucan synthesis and is highly expressed during fiber elongation. In this study, we report that GhMUR3 participates in cotton fiber development under the regulation of GhMYB30. Overexpression GhMUR3 affects the fiber elongation and cell wall thickening. Transcriptome showed that the expression of genes involved in secondary cell wall synthesis was prematurely activated in OE-MUR3 lines. In addition, GhMYB30 was identified as a key regulator of GhMUR3 by Y1H, Dual-Luc, and electrophoretic mobility shift assay (EMSA) assays. GhMYB30 directly bound the GhMUR3 promoter and activated GhMUR3 expression. Furthermore, DAP-seq of GhMYB30 was performed to identify its target genes in the whole genome. The results showed that many target genes were associated with fiber development, including cell wall synthesis-related genes, BR-related genes, reactive oxygen species pathway genes, and VLCFA synthesis genes. It was demonstrated that GhMYB30 may regulate fiber development through multiple pathways. Additionally, GhMYB46 was confirmed to be a target gene of GhMYB30 by EMSA, and GhMYB46 was significantly increased in GhMYB30-silenced lines, indicating that GhMYB30 inhibited GhMYB46 expression. Overall, these results revealed that GhMUR3 under the regulation of GhMYB30 and plays an essential role in cotton fiber elongation and secondary wall thickening. Additionally, GhMYB30 plays an important role in the regulation of fiber development and regulates fiber secondary wall synthesis by inhibiting the expression of GhMYB46.
木葡聚糖是一种重要的半纤维素，在维持细胞壁结构和细胞伸长中起着关键作用。然而，木葡聚糖对棉花纤维发育的影响尚不清楚。GhMUR3 编码一种木葡聚糖半乳糖基转移酶，该酶对于木葡聚糖的合成是必不可少的，并且在纤维伸长过程中高度表达。在这项研究中，我们报告 GhMUR3 在 GhMYB30 的调控下参与棉花纤维发育。过表达 GhMUR3 影响纤维伸长和细胞壁增厚。转录组分析表明，OE-MUR3 系中涉及次生细胞壁合成的基因表达过早激活。此外，通过 Y1H、双荧光素酶和电泳迁移率变动分析（EMSA）实验鉴定出 GhMYB30 是 GhMUR3 的关键调控因子。GhMYB30 直接结合 GhMUR3 启动子并激活 GhMUR3 表达。此外，通过 DAP-seq 分析鉴定了 GhMYB30 在全基因组中的靶基因。结果表明，许多靶基因与纤维发育有关，包括细胞壁合成相关基因、BR 相关基因、活性氧途径基因和 VLCFA 合成基因。表明 GhMYB30 可能通过多种途径调控纤维发育。此外，通过 EMSA 证实 GhMYB46 是 GhMYB30 的靶基因，并且在 GhMYB30 沉默系中 GhMYB46 显著增加，表明 GhMYB30 抑制了 GhMYB46 的表达。总之，这些结果表明，GhMUR3 在 GhMYB30 的调控下在棉花纤维伸长和次生壁增厚中发挥重要作用。此外，GhMYB30 通过抑制 GhMYB46 的表达在纤维发育的调控中起重要作用，并调节纤维次生壁合成。
