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.
Sanya Institute of China Agricultural University, Sanya, 572025, China.
J Integr Plant Biol. 2024 Feb;66(2):176-195. doi: 10.1111/jipb.13612. Epub 2024 Jan 31.
Sweet potato (Ipomoea batatas [L.] Lam.) is a crucial staple and bioenergy crop. Its abiotic stress tolerance holds significant importance in fully utilizing marginal lands. Transcriptional processes regulate abiotic stress responses, yet the molecular regulatory mechanisms in sweet potato remain unclear. In this study, a NAC (NAM, ATAF1/2, and CUC2) transcription factor, IbNAC087, was identified, which is commonly upregulated in salt- and drought-tolerant germplasms. Overexpression of IbNAC087 increased salt and drought tolerance by increasing jasmonic acid (JA) accumulation and activating reactive oxygen species (ROS) scavenging, whereas silencing this gene resulted in opposite phenotypes. JA-rich IbNAC087-OE (overexpression) plants exhibited more stomatal closure than wild-type (WT) and IbNAC087-Ri plants under NaCl, polyethylene glycol, and methyl jasmonate treatments. IbNAC087 functions as a nuclear transcriptional activator and directly activates the expression of the key JA biosynthesis-related genes lipoxygenase (IbLOX) and allene oxide synthase (IbAOS). Moreover, IbNAC087 physically interacted with a RING-type E3 ubiquitin ligase NAC087-INTERACTING E3 LIGASE (IbNIEL), negatively regulating salt and drought tolerance in sweet potato. IbNIEL ubiquitinated IbNAC087 to promote 26S proteasome degradation, which weakened its activation on IbLOX and IbAOS. The findings provide insights into the mechanism underlying the IbNIEL-IbNAC087 module regulation of JA-dependent salt and drought response in sweet potato and provide candidate genes for improving abiotic stress tolerance in crops.
甘薯（Ipomoea batatas [L.] Lam.）是一种重要的主食和生物能源作物。其对非生物胁迫的耐受性在充分利用边际土地方面具有重要意义。转录过程调控非生物胁迫响应，但甘薯中的分子调控机制尚不清楚。本研究鉴定了一个 NAC（NAM、ATAF1/2 和 CUC2）转录因子 IbNAC087，该基因在耐盐和耐旱种质中普遍上调表达。过表达 IbNAC087 通过增加茉莉酸（JA）积累和激活活性氧（ROS）清除来提高盐和干旱耐受性，而沉默该基因则导致相反的表型。富含 JA 的 IbNAC087-OE（过表达）植物在 NaCl、聚乙二醇和茉莉酸甲酯处理下比野生型（WT）和 IbNAC087-Ri 植物表现出更多的气孔关闭。IbNAC087 作为核转录激活因子，直接激活关键 JA 生物合成相关基因脂氧合酶（IbLOX）和丙二烯氧化物合酶（IbAOS）的表达。此外，IbNAC087 与 RING 型 E3 泛素连接酶 NAC087-INTERACTING E3 LIGASE（IbNIEL）发生物理相互作用，负调控甘薯的耐盐和耐旱性。IbNIEL 泛素化 IbNAC087 以促进 26S 蛋白酶体降解，从而削弱其对 IbLOX 和 IbAOS 的激活。这些发现为 IbNIEL-IbNAC087 模块调节甘薯中依赖 JA 的盐和干旱响应的机制提供了深入了解，并为提高作物非生物胁迫耐受性提供了候选基因。
