College of Life Sciences, Nanjing Agricultural University, Nanjing, 210095, China.
State Key Laboratory of Crop Genetics & Germplasm Enhancement and Utilization, Nanjing Agricultural University, Nanjing, 210095, China.
J Integr Plant Biol. 2024 Jun;66(6):1068-1086. doi: 10.1111/jipb.13662. Epub 2024 Apr 12.
Drought stress is a crucial environmental factor that limits plant growth, development, and productivity. Autophagy of misfolded proteins can help alleviate the damage caused in plants experiencing drought. However, the mechanism of autophagy-mediated drought tolerance in plants remains largely unknown. Here, we cloned the gene for a maize (Zea mays) selective autophagy receptor, NEXT TO BRCA1 GENE 1 (ZmNBR1), and identified its role in the response to drought stress. We observed that drought stress increased the accumulation of autophagosomes. RNA sequencing and reverse transcription-quantitative polymerase chain reaction showed that ZmNBR1 is markedly induced by drought stress. ZmNBR1 overexpression enhanced drought tolerance, while its knockdown reduced drought tolerance in maize. Our results established that ZmNBR1 mediates the increase in autophagosomes and autophagic activity under drought stress. ZmNBR1 also affects the expression of genes related to autophagy under drought stress. Moreover, we determined that BRASSINOSTEROID INSENSITIVE 1A (ZmBRI1a), a brassinosteroid receptor of the BRI1-like family, interacts with ZmNBR1. Phenotype analysis showed that ZmBRI1a negatively regulates drought tolerance in maize, and genetic analysis indicated that ZmNBR1 acts upstream of ZmBRI1a in regulating drought tolerance. Furthermore, ZmNBR1 facilitates the autophagic degradation of ZmBRI1a under drought stress. Taken together, our results reveal that ZmNBR1 regulates the expression of autophagy-related genes, thereby increasing autophagic activity and promoting the autophagic degradation of ZmBRI1a under drought stress, thus enhancing drought tolerance in maize. These findings provide new insights into the autophagy degradation of brassinosteroid signaling components by the autophagy receptor NBR1 under drought stress.
干旱胁迫是限制植物生长、发育和生产力的关键环境因素。错误折叠蛋白的自噬可以帮助减轻植物在经历干旱时所受到的损害。然而，植物中自噬介导的耐旱机制在很大程度上仍然未知。在这里，我们克隆了一个玉米（Zea mays）选择性自噬受体 NEXT TO BRCA1 GENE 1（ZmNBR1）的基因，并确定了它在响应干旱胁迫中的作用。我们观察到干旱胁迫会增加自噬体的积累。RNA 测序和反转录定量聚合酶链反应显示，ZmNBR1 明显受到干旱胁迫的诱导。ZmNBR1 的过表达增强了玉米的耐旱性，而其敲低则降低了玉米的耐旱性。我们的结果表明，ZmNBR1 介导了干旱胁迫下自噬体和自噬活性的增加。ZmNBR1 还影响干旱胁迫下与自噬相关的基因的表达。此外，我们确定了 BRASSINOSTEROID INSENSITIVE 1A（ZmBRI1a），一种 BRASSINOSTEROID 受体 BRI1 样家族的成员，与 ZmNBR1 相互作用。表型分析表明，ZmBRI1a 负调控玉米的耐旱性，遗传分析表明，ZmNBR1 在调控耐旱性方面位于 ZmBRI1a 的上游。此外，ZmNBR1 促进了干旱胁迫下 ZmBRI1a 的自噬降解。综上所述，我们的结果表明，ZmNBR1 调节自噬相关基因的表达，从而增加自噬活性，并促进干旱胁迫下 ZmBRI1a 的自噬降解，从而增强玉米的耐旱性。这些发现为自噬受体 NBR1 在干旱胁迫下调节 BRASSINOSTEROID 信号成分的自噬降解提供了新的见解。
