Thuy Nguyen Thi, Kim Hyun-Jung, Hong Suk-Whan
Department of the Integrative Food, Bioscience, and Biotechnology, College of Agriculture and Life Sciences Chonnam National University Gwangju Korea.
Plant Direct. 2024 Mar 23;8(3):e580. doi: 10.1002/pld3.580. eCollection 2024 Mar.
Plant genomes contain numerous genes encoding chitinase-like (CTL) proteins, which have a similar protein structure to chitinase belonging to the glycoside hydrolase (GH) family but lack the chitinolytic activity to cleave the -1,4-glycosidic bond in chitins, polymers of -acetylglucosamine. mutations found in rice and have caused pleiotropic developmental defects, including altered cell wall composition and decreased abiotic stress tolerance, likely due to reduced cellulose content. In this study, we identified () as a genetic suppressor of the mutation in . The mutation in restored almost all examined defects to nearly wild-type levels or at least partially. encodes a Golgi-located type II membrane protein with glycosyltransferase (GT) activity, and its mutations lead to a reduction in cellulose content and hypersensitivity to cellulose biosynthesis inhibitors, although to a lesser extent than mutation. The promoter fused with the GUS reporter gene exhibited GUS activity in interfascicular fibers and xylem in stems; meanwhile, the mutation significantly increased this activity. Our findings provide genetic and molecular evidence that the antagonistic activities of CTL1 and SUH1 play an essential role in assembling the cell wall in .
植物基因组包含众多编码几丁质酶样（CTL）蛋白的基因，这些蛋白具有与属于糖苷水解酶（GH）家族的几丁质酶相似的蛋白质结构，但缺乏切割几丁质（β-1,4-连接的N-乙酰葡糖胺聚合物）中β-1,4-糖苷键的几丁质分解活性。在水稻和拟南芥中发现的CTL1突变导致了多效性发育缺陷，包括细胞壁组成改变和非生物胁迫耐受性降低，这可能是由于纤维素含量减少所致。在本研究中，我们鉴定出SUH1作为拟南芥中CTL1突变的遗传抑制因子。SUH1突变几乎将所有检测到的CTL1缺陷恢复到接近野生型水平或至少部分恢复。SUH1编码一种具有糖基转移酶（GT）活性的定位于高尔基体的II型膜蛋白，其突变导致纤维素含量降低以及对纤维素生物合成抑制剂超敏，尽管程度小于CTL1突变。与GUS报告基因融合的SUH1启动子在茎的束间纤维和木质部中表现出GUS活性；同时，CTL1突变显著增加了这种活性。我们的研究结果提供了遗传和分子证据，表明CTL1和SUH1的拮抗活性在拟南芥细胞壁组装中起重要作用。
