Cold stress severely affects the growth and quality of tomato. 5-Aminolevulinic acid (ALA) can effectively improve tomato's cold stress tolerance. In this study, a tomato glutathione S-transferase gene, SlGSTU43, was identified. Results showed that ALA strongly induced the expression of SlGSTU43 under cold stress. SlGSTU43-overexpressing lines showed increased resistance to cold stress through an enhanced ability to scavenge reactive oxygen species. On the contrary, slgstu43 mutant lines were sensitive to cold stress, and ALA did not improve their cold stress tolerance. Thus, SlGSTU43 is a key gene in the process of ALA improving tomato cold tolerance. Through yeast library screening, SlMYB4 and SlMYB88 were preliminarily identified as transcription factors that bind to the SlGSTU43 promoter. Electrophoretic mobility shift, yeast one-hybrid, dual luciferase, and chromatin immunoprecipitation assays experiments verified that SlMYB4 and SlMYB88 can bind to the SlGSTU43 promoter. Further experiments showed that SlMYB4 and SlMYB88 are involved in the process of ALA-improving tomato’s cold stress tolerance and they positively regulate the expression of SlGSTU43. The findings provide new insights into the mechanism by which ALA improves cold stress tolerance. SlGSTU43, as a valuable gene, could be added to the cold-responsive gene repository. Subsequently, it could be used in genetic engineering to enhance the cold tolerance of tomato.

中文翻译：

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5-氨基乙酰丙酸通过调节SlMYB4/SlMYB88-SlGSTU43模块清除番茄中的活性氧提高抗寒性

低温胁迫严重影响番茄的生长和品质。5-氨基乙酰丙酸（ALA）能有效提高番茄的冷胁迫耐受性。在这项研究中，鉴定出了番茄谷胱甘肽 S-转移酶基因 SlGSTU43。结果表明，ALA在冷胁迫下强烈诱导SlGSTU43的表达。SlGSTU43过表达株系通过增强清除活性氧的能力而表现出对冷应激的抵抗力增强。相反，slgstu43突变株系对冷胁迫敏感，ALA并没有提高其冷胁迫耐受性。由此可见，SlGSTU43是ALA提高番茄耐寒性过程中的关键基因。通过酵母文库筛选，初步鉴定SlMYB4和SlMYB88为与SlGSTU43启动子结合的转录因子。电泳迁移率变动、酵母单杂交、双荧光素酶和染色质免疫沉淀实验验证了SlMYB4和SlMYB88可以与SlGSTU43启动子结合。进一步实验表明，SlMYB4和SlMYB88参与了ALA提高番茄冷胁迫耐受性的过程，并正向调控SlGSTU43的表达。这些发现为 ALA 提高冷应激耐受性的机制提供了新的见解。SlGSTU43作为一个有价值的基因，可以添加到冷响应基因库中。随后，它可以用于基因工程，以增强番茄的耐寒性。