INTRODUCTION Tomato (Solanum lycopersicum), a significant warm-season and water-dependent vegetable crop, is extensively cultivated worldwide. Whether grown in open fields or protected environments, tomatoes frequently encounter various environmental stresses, including drought and low temperatures, which significantly impact their yield and quality. Transcription factors play a pivotal role in plant stress responses by modulating the expression of specific target genes, thereby transmitting perceived stress signals downstream. WRKY transcription factors in tomatoes are known to regulate responses to multiple abiotic stresses. However, the specific role of the tomato SlWRKY45 in abiotic stress responses remains unclear.
RATIONALEStudies have demonstrated that WRKY transcription factors play a crucial regulatory role in plant responses to abiotic stress. As an important economic vegetable crop, tomato is susceptible to various environmental stresses during its growth and development. By genetically overexpressing SlWRKY45 in tomato and investigating its function under low-temperature and drought stress conditions, the findings can provide a theoretical foundation for understanding the complex regulatory mechanisms of WRKY transcription factors. Additionally, this research offers valuable candidate genes for breeding stress-resistant tomato varieties.
RESULTSExpression analysis revealed that low-temperature, drought, and abscisic acid (ABA) treatments significantly induced the expression of SlWRKY45. Overexpression of SlWRKY45 enhanced the resistance of tomato plants to drought and low-temperature stresses. Under drought and low-temperature conditions, the photosynthetic indices, antioxidant enzyme activities, and proline (Pro) contents in SlWRKY45 overexpression lines were significantly higher than those in wild-type (WT) plants. Conversely, the accumulation of reactive oxygen species (ROS) and malondialdehyde (MDA) levels in SlWRKY45-OE plants was significantly lower than in WT plants under the same stress conditions. Transcriptome data analysis indicated that SlWRKY45 regulates tomato's response to low-temperature stress primarily by influencing antioxidant enzyme activities and stress response pathways. Dual-luciferase assays demonstrated that SlWRKY45 could directly activate the expression of SlPOD1. Furthermore, the interaction between SlWRKY45 and SlWRKY46 was confirmed through yeast two-hybrid (Y2H) and bimolecular fluorescence complementation (BiFC) assays.
CONCLUSIONOur findings demonstrate that SlWRKY45 positively regulates drought resistance and low-temperature tolerance in tomato. Additionally, SlWRKY45 can interact with SlWRKY46 and directly activate the expression of SlPOD1. These results offer valuable insights for further research into the regulatory mechanisms underlying abiotic stress responses and provide potential gene resources for genetic improvement through molecular breeding.
Phenotypes of SlWRKY45-overexpressing and wild-type plants under drought and low-temperature treatments
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |