Sanya Institute of China Agricultural University, Sanya 572025, China.
Key Laboratory of Sweet Potato Biology and Biotechnology, Ministry of Agriculture and Rural Affairs/Beijing Key Laboratory of Crop Genetic Improvement/Laboratory of Crop Heterosis & Utilization and Joint Laboratory for International Cooperation in Crop Molecular Breeding, Ministry of Education, College of Agronomy & Biotechnology, China Agricultural University, Beijing 100193, China.
Plant Physiol. 2024 Jan 31;194(2):787-804. doi: 10.1093/plphys/kiad532.
Root development influences plant responses to environmental conditions, and well-developed rooting enhances plant survival under abiotic stress. However, the molecular and genetic mechanisms underlying root development and abiotic stress tolerance in plants remain unclear. In this study, we identified the MYB transcription factor-encoding gene IbMYB73 by cDNA-amplified fragment length polymorphism and RNA-seq analyses. IbMYB73 expression was greatly suppressed under abiotic stress in the roots of the salt-tolerant sweet potato (Ipomoea batatas) line ND98, and its promoter activity in roots was significantly reduced by abscisic acid (ABA), NaCl, and mannitol treatments. Overexpression of IbMYB73 significantly inhibited adventitious root growth and abiotic stress tolerance, whereas IbMYB73-RNAi plants displayed the opposite pattern. IbMYB73 influenced the transcription of genes involved in the ABA pathway. Furthermore, IbMYB73 formed homodimers and activated the transcription of ABA-responsive protein IbGER5 by binding to an MYB binding sites I motif in its promoter. IbGER5 overexpression significantly inhibited adventitious root growth and abiotic stress tolerance concomitantly with a reduction in ABA content, while IbGER5-RNAi plants showed the opposite effect. Collectively, our results demonstrated that the IbMYB73-IbGER5 module regulates ABA-dependent adventitious root growth and abiotic stress tolerance in sweet potato, which provides candidate genes for the development of elite crop varieties with well-developed root-mediated abiotic stress tolerance.
根系发育影响植物对环境条件的响应，发达的根系增强了植物在非生物胁迫下的生存能力。然而，植物根系发育和非生物胁迫耐受性的分子和遗传机制仍不清楚。在这项研究中，我们通过 cDNA 扩增片段长度多态性和 RNA-seq 分析鉴定了 MYB 转录因子编码基因 IbMYB73。在耐盐甘薯（Ipomoea batatas）ND98 根中，IbMYB73 的表达在非生物胁迫下受到极大抑制，其启动子活性在根中被脱落酸（ABA）、NaCl 和甘露醇处理显著降低。IbMYB73 的过表达显著抑制不定根生长和非生物胁迫耐受性，而 IbMYB73-RNAi 植物则表现出相反的模式。IbMYB73 影响参与 ABA 途径的基因的转录。此外，IbMYB73 形成同源二聚体并通过结合其启动子中的 MYB 结合位点 I 基序激活 ABA 响应蛋白 IbGER5 的转录。IbGER5 的过表达显著抑制不定根生长和非生物胁迫耐受性，同时 ABA 含量降低，而 IbGER5-RNAi 植物则表现出相反的效果。总之，我们的研究结果表明，IbMYB73-IbGER5 模块调节甘薯中 ABA 依赖的不定根生长和非生物胁迫耐受性，为开发具有发达根系介导的非生物胁迫耐受性的优良作物品种提供了候选基因。
