番茄(Solanum lycopersicum)在生长发育过程中常受到低温、干旱等多种非生物胁迫的影响。WRKY转录因子参与调控植物多种非生物胁迫响应过程, 而SlWRKY45在番茄非生物胁迫中功能尚不清楚。表达分析发现低温、干旱和ABA处理均可显著诱导SlWRKY45的表达; 过表达SlWRKY45可提高番茄对干旱和低温的抗性; 在干旱和低温处理下, 过表达株系光合指标、抗氧化酶活性和脯氨酸(Pro)含量显著高于野生型, 活性氧(ROS)积累和丙二醛(MDA)含量显著低于WT。转录组数据分析表明, SlWRKY45主要通过影响抗氧化酶活性和胁迫响应途径调控番茄对低温胁迫的响应。双荧光素酶试验分析发现, SlWRKY45可直接激活SlPOD1的表达。酵母双杂交(Y2H)和双分子荧光互补(BiFC)试验结果发现, SlWRKY45与SlWRKY46存在相互作用。上述研究表明SlWRKY45可能通过直接调控抗氧化酶途径增强转基因番茄的抗逆性, 为番茄的遗传改良提供了可用的候选基因资源。

Tomato is usually affected by various abiotic stresses such as low temperature and drought during its growth and development. WRKY transcription factors are involved in the regulation of different plant abiotic stress responses. However, the function of tomato SlWRKY45 in abiotic stress response remains unknown. The expression analysis showed that low temperature, drought and abscisic acid (ABA) treatments could significantly induced the expression of SlWRKY45. Overexpression of SlWRKY45 improved the resistance of tomato to drought and low temperature stresses. The photosynthetic indices, antioxidase activities and proline (Pro) contents of overexpression lines (SlWRKY45-OE) were significantly higher than those of wild type (WT) under drought and low temperature treatments. While the accumulation of reactive oxygen species (ROS) and malondialdehyde (MDA) contents of SlWRKY45-OE were significantly lower than those of WT under drought and low temperature treatments. The transcriptome data analysis showed that SlWRKY45 regulated tomato response to low temperature stress mainly by affecting antioxidase activities and stress response pathways. The analysis of double luciferase assay showed that SlWRKY45 could directly activate the expression of SlPOD1. Moreover, the interaction between SlWRKY45 and SlWRKY46 was confirmed by yeast two-hybrid (Y2H) and bimolecular fluorescence complementation (BiFC). These findings indicate that SlWRKY45 plays important roles in tomato resistance to low temperature and drought stresses, and provide potential gene resource in genetic improvement through molecular breeding.