Chen Xingxiang, Liu Kui, Luo Tingting, Zhang Baolei, Yu Jinyu, Ma Dan, Sun Xiaoqian, Zheng Huawei, Xin Boning, Xia Jixing
State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Life Science and Technology, Guangxi University, Nanning 530004, China.
Plant Cell. 2024 Dec 23;37(1). doi: 10.1093/plcell/koae278.
In response to variable environments, rice (Oryza sativa) roots have developed lignified and suberized diffusion barriers at the endodermis to permit selective nutrient uptake for optimal growth. Here, we demonstrate that endodermal suberization and nonlocalized lignification are redundantly regulated by 4 MYB transcription factors: OsMYB39a, OsMYB41, OsMYB92a, and OsMYB92b. These transcription factors function downstream of the OsMYB36a/b/c, CASPARIAN STRIP INTEGRITY FACTOR (OsCIF)-SCHENGEN3 (OsSGN3), and stress-inducible signaling pathways in rice. Knockout of all 4 MYB genes resulted in the complete absence of endodermal suberin lamellae (SL) and almost no lignin deposition between the Casparian strip and the cortex-facing lignified band at cell corners under all conditions examined. In contrast, endodermis-specific overexpression of any of these MYB genes was sufficient to induce strong endodermal suberization and nonlocalized lignification near the root tip. Furthermore, OsMYB92a-overexpressing lines showed an altered ionomic profile and enhanced salinity tolerance. Transcriptome analysis identified 152 downstream genes regulated by OsMYB39a/41/92a/92b, including the key SL formation gene OsCYP86A1 and other genes involved in endodermal lignification and suberization under normal and stress conditions. Our results provide important insights into the molecular mechanisms underlying suberization and nonlocalized lignification at the root endodermis and their physiological significance in ion homeostasis and acclimation to environmental stress.
为响应多变的环境，水稻（Oryza sativa）根系在内皮层形成了木质化和栓质化的扩散屏障，以实现选择性养分吸收，从而实现最佳生长。在此，我们证明内皮层栓质化和非局部木质化由4个MYB转录因子冗余调控：OsMYB39a、OsMYB41、OsMYB92a和OsMYB92b。这些转录因子在水稻的OsMYB36a/b/c、凯氏带完整性因子（OsCIF）-SCHENGEN3（OsSGN3）和胁迫诱导信号通路的下游发挥作用。在所有检测条件下，敲除所有4个MYB基因导致内皮层栓质化层（SL）完全缺失，并且在细胞角隅处的凯氏带与面向皮层的木质化带之间几乎没有木质素沉积。相反，这些MYB基因中的任何一个在内皮层特异性过表达足以诱导根尖附近强烈的内皮层栓质化和非局部木质化。此外，过表达OsMYB92a的株系显示出离子组学特征改变和耐盐性增强。转录组分析鉴定出152个受OsMYB39a/41/92a/92b调控的下游基因，包括关键的SL形成基因OsCYP86A1以及在正常和胁迫条件下参与内皮层木质化和栓质化的其他基因。我们的结果为根内皮层栓质化和非局部木质化的分子机制及其在离子稳态和适应环境胁迫中的生理意义提供了重要见解。
