Department of Applied Biology, Chonnam National University, Gwangju, Republic of Korea.
Department of Rural and Biosystems Engineering, Agricultural Robotics and Automation Research Center, Chonnam National University, Gwangju, Republic of Korea.
J Exp Bot. 2021 Feb 2;72(2):636-653. doi: 10.1093/jxb/eraa458.
Proline (Pro) metabolism plays important roles in protein synthesis, redox balance, and abiotic stress response. However, it is not known if cross-talk occurs between proline and brassinosteroid (BR) signaling pathways. Here, an Arabidopsis intergenic enhancer double mutant, namely proline content alterative 41 (pca41), was generated by inserting a T-DNA tag in the Arabidopsis thaliana ring zinc finger 1 (atrzf1 ) mutant background. pca41 had a T-DNA inserted at the site of the gene encoding BES1/BZR1 Homolog 3 (BEH3). pca41 has a drought-insensitive phenotype that is stronger than atrzf1 under osmotic stress, including high Pro accumulation and decreased amounts of reactive oxygen species. Analysis of physiological, genetic, and molecular networks revealed that negative regulation of BEH3 during abiotic stress was linked to the BR signaling pathway. Our data also suggest that AtRZF1, an E3 ubiquitin ligase, might control osmotic stress, abscisic acid, and BR responses in a BEH3-dependent manner. Under darkness, pca41 displays a long hypocotyl phenotype, which is similar to atrzf1 and beh3, suggesting that BEH3 acts in the same pathway as AtRZF1. Overexpression of BEH3 results in an osmotic stress-sensitive phenotype, which is reversed by exogenous BR application. Taken together, our results indicate that AtRZF1 and BEH3 may play important roles in the osmotic stress response via ubiquitination and BR signaling.
脯氨酸（Pro）代谢在蛋白质合成、氧化还原平衡和非生物胁迫响应中起着重要作用。然而，脯氨酸和油菜素内酯（BR）信号通路之间是否存在串扰尚不清楚。在这里，通过在拟南芥环锌指 1（atrzf1）突变体背景中插入 T-DNA 标签，生成了一个拟南芥基因间增强子双突变体，即脯氨酸含量改变 41（pca41）。pca41 有一个 T-DNA 插入到编码 BES1/BZR1 同源物 3（BEH3）的基因位点。pca41 在渗透胁迫下表现出比 atrzf1 更强的抗旱表型，包括脯氨酸积累增加和活性氧物质减少。生理、遗传和分子网络分析表明，BEH3 在非生物胁迫下的负调控与 BR 信号通路有关。我们的数据还表明，E3 泛素连接酶 AtRZF1 可能以依赖于 BEH3 的方式控制渗透胁迫、脱落酸和 BR 反应。在黑暗中，pca41 表现出长下胚轴表型，与 atrzf1 和 beh3 相似，表明 BEH3 与 AtRZF1 处于相同的途径。BEH3 的过表达导致对渗透胁迫敏感的表型，而外源 BR 的应用可逆转该表型。总之，我们的结果表明，AtRZF1 和 BEH3 可能通过泛素化和 BR 信号在渗透胁迫反应中发挥重要作用。
