Key Laboratory of Biology and Genetic Improvement of Maize in Southwest Region, Ministry of Agriculture, Maize Research Institute, Sichuan Agricultural University, Chengdu, 611130, China.
International Maize and Wheat Improvement Center (CIMMYT), Texcoco, 56237, Mexico.
Plant Physiol Biochem. 2023 Dec;205:108188. doi: 10.1016/j.plaphy.2023.108188. Epub 2023 Nov 14.
Drought stress is a common abiotic factor and restricts plant growth and development. Exploring maize stress-related genes and their regulatory mechanisms is crucial for ensuring agricultural productivity and food security. The BRI1-EMS1 suppressor (BES1)/brassinazole-resistant 1 (BZR1) transcription factors (TFs) play important roles in plant growth, development, and stress response. However, maize ZmBES1/BZR1s are rarely reported. In the present study, the ZmBES1/BZR1-1 gene was cloned from maize B73 and functionally characterized in transgenic Arabidopsis and rice in drought stress response. The ZmBES1/BZR1-1 protein possessed a conserved bHLH domain characterized by BES1/BZR1 TFs, localized in the nucleus, and showed transcription activation activity. The expression of ZmBES1/BZR1-1 exhibited no tissue specificity but drought-inhibitory expression in maize. Under drought stress, overexpression of ZmBES1/BZR1-1 resulted in the enhancement of drought sensitivity of transgenic Arabidopsis and rice with a lower survival rate, reactive oxygen species (ROS) level and relative water content (RWC) and a higher stomatal aperture and relative electrolyte leakage (REL). The RNA-seq results showed that 56 differentially expressed genes (DEGs) were regulated by ZmBES1/BZR1-1 by binding to E-box elements in their promoters. The GO analysis showed that the DEGs were significantly annotated with response to oxidative stress and oxygen level. The study suggests that the ZmBES1/BZR1-1 gene negatively regulates drought stress, which provides insights into further underlying molecular mechanisms in the drought stress response mediated by BZR1/BES1s.
干旱胁迫是一种常见的非生物因素，限制了植物的生长和发育。探索与玉米胁迫相关的基因及其调控机制对于确保农业生产力和粮食安全至关重要。BRI1-EMS1 抑制子（BES1）/油菜素内酯抗性 1（BZR1）转录因子（TFs）在植物生长、发育和胁迫响应中发挥重要作用。然而，玉米 ZmBES1/BZR1s 很少被报道。本研究从玉米 B73 中克隆了 ZmBES1/BZR1-1 基因，并在转基因拟南芥和水稻中对其在干旱胁迫响应中的功能进行了表征。ZmBES1/BZR1-1 蛋白具有 BES1/BZR1 TFs 特征的保守 bHLH 结构域，定位于细胞核内，具有转录激活活性。ZmBES1/BZR1-1 的表达没有组织特异性，但在玉米中表现出干旱抑制表达。在干旱胁迫下，过表达 ZmBES1/BZR1-1 导致转基因拟南芥和水稻的抗旱性增强，存活率降低，活性氧（ROS）水平和相对含水量（RWC）升高，气孔开度和相对电解质泄漏（REL）升高。RNA-seq 结果表明，56 个差异表达基因（DEGs）受 ZmBES1/BZR1-1 调控，通过结合其启动子中的 E-box 元件。GO 分析表明，DEGs 显著注释为响应氧化应激和氧水平。该研究表明，ZmBES1/BZR1-1 基因负调控干旱胁迫，为进一步深入了解 BZR1/BES1s 介导的干旱胁迫响应的分子机制提供了依据。
