Department of Biology and Geology, CIAIMBITAL Research Centers. University of Almería, 04120 Almería, Spain.
Department of Chemistry and Physics, CAESCG Research Centers. University of Almería, 04120 Almería, Spain.
Plant Sci. 2023 Nov;336:111853. doi: 10.1016/j.plantsci.2023.111853. Epub 2023 Sep 1.
The squash gain-of-function mutant etr2b disrupts the ethylene-binding domain of ethylene receptor CpETR2B, conferring partial ethylene insensitivity, changes in flower and fruit development, and enhanced salt tolerance. In this paper, we found that etr2b also confers a growth advantage as well as a physiological and metabolomic response that make the mutant better adapted to drought. Mutant plants had a higher root and leaf biomass than WT under both well-watered and drought conditions, but the reduction in growth parameters in response to drought was similar in WT and etr2b. Water deficit reduced all gas-exchange parameters in both WT and etr2b, but under moderate drought the mutant increased photosynthesis rate in comparison with control conditions, and showed a higher leaf CO concentration, transpiration rate, and stomata conductance than WT. The response of etr2b to drought indicates that ethylene is a negative regulator of plant growth under both control and drought. Since etr2b increased ABA content in well-watered plant, but prevented the induction of ABA production in response to drought, it is likely that the etr2b response under drought is not mediated by ABA. A H NMR metabolomic analysis revealed that etr2b enhances the accumulation of osmolytes (soluble sugars and trigonelline), unsaturated and polyunsaturated fatty acids, and phenolic compounds under drought, concomitantly with a reduction of malic- and fumaric-acid. The role of CpETR2B and ethylene in the regulation of these drought-protective metabolites is discussed.
蔓绿绒黄化突变体 etr2b 破坏了乙烯受体 CpETR2B 的乙烯结合域，导致部分乙烯不敏感、花和果实发育改变以及增强的耐盐性。在本文中，我们发现 etr2b 还赋予了生长优势以及生理和代谢组学响应，使突变体更好地适应干旱。在充分浇水和干旱条件下，突变体植物的根和叶生物量均高于 WT，但 WT 和 etr2b 对干旱的生长参数降低相似。水分亏缺降低了 WT 和 etr2b 中的所有气体交换参数，但在中度干旱下，与对照条件相比，突变体增加了光合作用速率，并表现出比 WT 更高的叶片 CO2 浓度、蒸腾速率和气孔导度。etr2b 对干旱的响应表明，乙烯是控制和干旱条件下植物生长的负调节剂。由于 etr2b 在充分浇水的植物中增加了 ABA 含量，但防止了 ABA 产量对干旱的诱导，因此，etr2b 在干旱下的响应可能不是由 ABA 介导的。1H NMR 代谢组学分析表明，etr2b 在干旱下增强了渗透调节剂（可溶性糖和千里光碱）、不饱和和多不饱和脂肪酸以及酚类化合物的积累，同时减少了苹果酸和延胡索酸。讨论了 CpETR2B 和乙烯在这些干旱保护代谢物调节中的作用。
