Key Laboratory of Horticultural Crop Biology and Germplasm Innovation in South China, Ministry of Agriculture, College of Horticulture, South China Agricultural University, Guangzhou 510642, China.
Institute of Bioengineering, Guangdong Academy of Sciences, Guangzhou 510316, China.
Int J Mol Sci. 2021 Mar 25;22(7):3347. doi: 10.3390/ijms22073347.
Auxin response factors (ARFs) play important roles in various plant physiological processes; however, knowledge of the exact role of ARFs in plant responses to water deficit is limited. In this study, SlARF4, a member of the ARF family, was functionally characterized under water deficit. Real-time fluorescence quantitative polymerase chain reaction (PCR) and -glucuronidase (GUS) staining showed that water deficit and abscisic acid (ABA) treatment reduced the expression of . was expressed in the vascular bundles and guard cells of tomato stomata. Loss of function of SlARF4 () by using Clustered Regularly Interspaced Short Palindromic Repeats/Cas 9 (CRISPR/Cas 9) technology enhanced plant resistance to water stress and rehydration ability. The mutant plants exhibited curly leaves and a thick stem. Malondialdehyde content was significantly lower in mutants than in wildtype plants under water stress; furthermore, mutants showed higher content of antioxidant substances, superoxide dismutase, actual photochemical efficiency of photosystem II (PSII), and catalase activities. Stomatal and vascular bundle morphology was changed in mutants. We identified 628 differentially expressed genes specifically expressed under water deficit in mutants; six of these genes, including ABA signaling pathway-related genes, were differentially expressed between the wildtype and mutants under water deficit and unlimited water supply. Auxin responsive element (AuxRE) elements were found in these genes' promoters indicating that SlARF4 participates in ABA signaling pathways by regulating the expression of and , thereby influencing stomatal morphology and vascular bundle development and ultimately improving plant resistance to water deficit.
生长素响应因子 (ARF) 在各种植物生理过程中发挥重要作用；然而，ARF 在植物对水分亏缺响应中的确切作用知之甚少。在这项研究中，SlARF4，ARF 家族的一员，在水分亏缺下的功能特征进行了研究。实时荧光定量聚合酶链反应 (PCR) 和β-葡萄糖醛酸酶 (GUS) 染色显示，水分亏缺和脱落酸 (ABA) 处理降低了 的表达。 在番茄气孔的维管束和保卫细胞中表达。使用成簇规律间隔短回文重复/ Cas9 (CRISPR/Cas9) 技术使 SlARF4 () 功能丧失增强了植物对水分胁迫和再水合能力的抗性。SlARF4 突变体 () 表现出卷曲的叶片和粗壮的茎。在水分胁迫下，突变体中的丙二醛含量明显低于野生型；此外，突变体表现出更高含量的抗氧化物质、超氧化物歧化酶、实际光系统 II (PSII) 的光化学效率和过氧化氢酶活性。突变体中的气孔和维管束形态发生变化。我们鉴定了 628 个在突变体中水分亏缺下特异性表达的差异表达基因；其中 6 个基因，包括 ABA 信号通路相关基因，在水分亏缺和无限供水下，野生型和突变体之间的表达存在差异。在这些基因的启动子中发现了生长素响应元件 (AuxRE) 元件，表明 SlARF4 通过调节 和 的表达参与 ABA 信号通路，从而影响气孔形态和维管束发育，最终提高植物对水分亏缺的抗性。
