Javed Sidra, Chai Xiangzheng, Huang Liuying, Wang Junzhe, Xu Shengbao
State Key Laboratory for Crop Stress Resistance and High-Efficiency Production, College of Agronomy, Northwest A&F University, Yangling, 712100, Shaanxi, China.
Plant Cell Rep. 2025 Jun 30;44(7):162. doi: 10.1007/s00299-025-03532-8.
The Radiation Sensitive 23B (RAD23B) protein functions upstream of the E3 ubiquitin ligase Embryo Sac Development Arrest 40 (EDA40), collaborating to regulate root architecture and affects the length of the root apical meristem. An optimal root system architecture plays a crucial role in water and mineral uptake in plants, primarily governed by the regulation of primary and lateral root development. Radiation Sensitive 23B (RAD23B), an ubiquitin-like/ubiquitin-associated (UBL/UBA) shuttle protein, mediates protein degradation through the ubiquitin/26S proteasome system (UPS) and is essential for plant root development. However, the mechanisms by which RAD23B regulates root development and whether this regulation depends on the UPS, are still unclear. In this study, an activation tagging-based suppressor screen was performed in the rad23b background, leading to the identification of Embryo Sac Development Arrest 40 (EDA40) as a new root growth regulator. EDA40 encodes an E3 ubiquitin ligase, which serves as a part of UPS. The overexpression of EDA40 rescues the root growth defects of rad23b, while the eda40 null mutant exhibits obvious root developmental defects. However, the overexpression of RAD23B is unable to suppress the root defects of eda40. Notably, the rad23b eda40 double mutant displays a root defect as severe as rad23b, suggesting that RAD23 may function upstream of EDA40. Together, these findings uncover a novel genetic relationship between RAD23B and EDA40 in root development and offer new insights into the role of the UPS in shaping root system architecture.
辐射敏感23B（RAD23B）蛋白在E3泛素连接酶胚囊发育停滞40（EDA40）的上游发挥作用，协同调节根系结构，并影响根顶端分生组织的长度。最佳的根系结构在植物吸收水分和矿物质方面起着至关重要的作用，这主要由主根和侧根发育的调控来决定。辐射敏感23B（RAD23B）是一种泛素样/泛素相关（UBL/UBA）穿梭蛋白，通过泛素/26S蛋白酶体系统（UPS）介导蛋白质降解，对植物根系发育至关重要。然而，RAD23B调节根系发育的机制以及这种调节是否依赖于UPS，目前仍不清楚。在本研究中，在rad23b背景下进行了基于激活标签的抑制子筛选，从而鉴定出胚囊发育停滞40（EDA40）作为一种新的根系生长调节因子。EDA40编码一种E3泛素连接酶，它是UPS的一部分。EDA40的过表达挽救了rad23b的根系生长缺陷，而eda40缺失突变体表现出明显的根系发育缺陷。然而，RAD23B的过表达无法抑制eda40的根系缺陷。值得注意的是，rad23b eda40双突变体表现出与rad23b一样严重的根系缺陷，这表明RAD23可能在EDA40的上游发挥作用。总之，这些发现揭示了RAD23B和EDA40在根系发育中的一种新的遗传关系，并为UPS在塑造根系结构中的作用提供了新的见解。
