Laboratory of Molecular Biology of Tomato, Bioengineering College, Chongqing University, Chongqing, PR China.
College of Agriculture/Mudan, Henan University of Science and Technology, Henan Province, PR China.
Plant Physiol Biochem. 2022 Dec 15;193:139-152. doi: 10.1016/j.plaphy.2022.10.026. Epub 2022 Nov 4.
High salinity and drought stresses often cause plants to produce ROS, including hydrogen peroxide (HO) and superoxide (O), which interfere with plant growth and affect crop yield. The transcription factors of the MYB family are involved in responses to biotic and abiotic stresses. Here, we isolated the R2R3-MYB transcription factor gene SlMYB50 and found that silencing of SlMYB50 increased resistance to PEG 6000, mannitol and salt. In addition, the resistance of transgenic tomatoes increased under high salt and drought stress. After stress treatment, the relative water content, chlorophyll content (critical for carbon fixation) and root vitality of the SlMYB50-RNAi lines were higher than those of the wild-type (WT). The opposite was true the water loss rate, relative conductivity, and MDA (as a sign of cell wall disruption). Under drought stress conditions, SlMYB50-silenced lines exhibited less HO and less O accumulation, as well as higher CAT enzyme activity, than were exhibited by the WT. Notably, after stress treatment, the expression levels of chlorophyll-synthesis-related, flavonoid-synthesis-related, carotenoid-related, antioxidant-enzyme-related and ABA-biosynthesis-related genes were all upregulated in SlMYB50-silenced lines compared to those of WT. A dual-luciferase reporter system was used to verify that SlMYB50 could bind to the CHS1 promoter. In summary, this study identified essential roles for SlMYB50 in regulating drought and salt tolerance.
高盐和干旱胁迫通常会导致植物产生 ROS，包括过氧化氢 (HO) 和超氧阴离子 (O)，这会干扰植物生长并影响作物产量。MYB 家族的转录因子参与了生物和非生物胁迫的反应。在这里，我们分离了 R2R3-MYB 转录因子基因 SlMYB50，并发现 SlMYB50 的沉默增加了对 PEG 6000、甘露醇和盐的抗性。此外，转基因番茄在高盐和干旱胁迫下的抗性增加。胁迫处理后，SlMYB50-RNAi 系的相对水含量、叶绿素含量（对碳固定至关重要）和根活力均高于野生型（WT）。相反，失水率、相对电导率和 MDA（作为细胞壁破坏的标志）则更低。在干旱胁迫条件下，SlMYB50 沉默系的 HO 和 O 积累较少，CAT 酶活性较高，而 WT 则相反。值得注意的是，胁迫处理后，SlMYB50 沉默系中与叶绿素合成、类黄酮合成、类胡萝卜素相关、抗氧化酶相关和 ABA 生物合成相关的基因表达水平均高于 WT。双荧光素酶报告系统验证了 SlMYB50 可以结合 CHS1 启动子。综上所述，本研究鉴定了 SlMYB50 在调节干旱和耐盐性方面的重要作用。
