State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan, 430072, China.
Ezhou Seed Technology Research Institute of Hubei Province, Ezhou, 436043, China.
Plant Cell Rep. 2022 Jan;41(1):221-232. doi: 10.1007/s00299-021-02804-3. Epub 2021 Oct 25.
ipa1 enhances rice drought tolerance mainly through activating the ABA pathway. It endows rice seedlings with a more developed root system, smaller leaf stomata aperture, and enhanced carbon metabolism. Drought is a major abiotic stress to crop production. IPA1 (IDEAL PLANT ARCHITECTURE 1)/OsSPL14 encodes a transcription factor and has been reported to function in both rice ideal plant architecture and biotic resistance. Here, with a pair of IPA1 and ipa1-NILs (Near Iso-genic Lines), we found that ipa1 could significantly improve rice drought tolerance at seedling stage. The ipa1 plants had a better-developed root system and smaller leaf stomatal aperture. Analysis of carbon-nitrogen metabolism-associated enzyme activity, gene expression, and metabolic profile indicated that ipa1 could tip the carbon-nitrogen metabolism balance towards an increased carbon metabolism pattern. In both the control and PEG-treated conditions, ABA content in the ipa1 seedlings was significantly higher than that in the IPA1 seedlings. Expression of the ABA biosynthesis genes was detected to be up-regulated, whereas the expression of ABA catabolism genes was down-regulated in the ipa1 seedlings. In addition, based on yeast one-hybrid assay and dual-luciferase assay, IPA1 was found to directly activate the promoter activity of OsHOX12, a transcription factor promoting ABA biosynthesis, and OsNAC52, a positive regulator of the ABA pathway. The expression of OsHOX12 and OsNAC52 was significantly up-regulated in the ipa1 plants. Combined with the previous studies, our results suggested that ipa1 could improve rice seedling drought tolerance mainly through activating the ABA pathway and that regulation of the ipa1-mediated ABA pathway will be an important strategy for improving drought resistance of rice.
要点：ipa1 主要通过激活 ABA 途径增强水稻的耐旱性。它赋予水稻幼苗更发达的根系、更小的叶片气孔孔径和增强的碳代谢。干旱是作物生产的主要非生物胁迫之一。IPA1（理想植物结构 1）/OsSPL14 编码一种转录因子，已被报道在水稻理想植物结构和生物抗性中发挥作用。在这里，我们使用一对 IPA1 和 ipa1-NILs（近等基因系），发现 ipa1 可以显著提高水稻幼苗期的耐旱性。ipa1 植株具有更发达的根系和更小的叶片气孔孔径。对碳氮代谢相关酶活性、基因表达和代谢谱的分析表明，ipa1 可以使碳氮代谢平衡向增加碳代谢模式倾斜。在对照和 PEG 处理条件下，ipa1 幼苗中的 ABA 含量明显高于 IPA1 幼苗。检测到 ABA 生物合成基因的表达上调，而 ABA 分解代谢基因的表达下调。此外，基于酵母单杂交测定和双荧光素酶测定，发现 IPA1 可以直接激活促进 ABA 生物合成的转录因子 OsHOX12 和 ABA 途径的正调节剂 OsNAC52 的启动子活性。ipa1 植株中 OsHOX12 和 OsNAC52 的表达明显上调。结合以前的研究，我们的结果表明，ipa1 主要通过激活 ABA 途径来提高水稻幼苗的耐旱性，调节 ipa1 介导的 ABA 途径将是提高水稻耐旱性的重要策略。
