Abstract：
Drought is a major handicap for plant growth and development. WRKY proteins comprise one of the largest families of plant transcription factors, playing important roles in plant growth and stress tolerance. In tomato (Solanum lycopersicum L.), different WRKY transcription factors differentially (positively or negatively) regulate drought tolerance, however, the role of SlWRKY6 in drought response and the associated molecular mechanisms of stress tolerance remain unclear. Here we report that SlWRKY6, a member of the WRKYII-b group, is involved in the functional aspects of drought resistance in tomato. Transcriptional activation assays show that SlWRKY6 is transcriptionally active in yeast cells, while the subcellular localization assay indicates that SlWRKY6 is localized in the nucleus. Overexpression of SlWRKY6 in tomato plants resulted in stronger antioxidant capacity and drought resistance as manifested by increased photosynthetic capacity and decreased reactive oxygen species accumulation, malondialdehyde content and relative electrolyte leakage in transgenic tomato plants compared with wild-type under drought stress. Moreover, increased abscisic acid (ABA) content and transcript abundance of ABA synthesis and signaling genes (NCED1, NCED4, PYL4, AREB1 and SnRK2.6) in the transgenic tomato plants indicated potential involvement of the ABA pathway in SlWRKY6-induced drought resistance in tomato plants. Inspection of 2-kb sequences upstream of the predicted binding sites in the promoter of SlNCED1/4 identified two copies of the core W-box (TTGACC/T) sequence in the promoter of SlNCED1/4, which correlates well with the expression of these genes in response to drought, further suggesting the involvement of ABA-dependent pathway in SlWRKY6-induced drought resistance. The study unveils a critical role of SlWRKY6, which can be useful to further reveal the drought tolerance mechanism and breeding of drought-resistant tomato varieties for sustainable vegetable production in the era of climate change.
摘要：
干旱是植物生长发育的主要障碍。WRKY蛋白是植物转录因子的最大家族之一,在植物生长和抗逆性中起着重要作用。在番茄（SolanumlycopersicumL.）中，不同的WRKY转录因子差异（正或负）调节耐旱性，然而,SlWRKY6在干旱响应中的作用以及相关的抗逆分子机制尚不清楚。在这里，我们报告了WRKYII-b组的成员SlWRKY6，涉及番茄抗旱性的功能方面。转录激活实验表明，SlWRKY6在酵母细胞中具有转录活性，而亚细胞定位分析表明SlWRKY6位于细胞核中。在番茄植株中过度表达SlWRKY6导致更强的抗氧化能力和抗旱性，表现为光合能力增加和活性氧积累减少。与干旱胁迫下的野生型相比，转基因番茄植株中的丙二醛含量和相对电解质渗漏。此外，转基因番茄植物中脱落酸（ABA）含量和ABA合成和信号基因（NCED1，NCED4，PYL4，AREB1和SnRK2.6）的转录本丰度增加，表明ABA途径可能参与SlWRKY6诱导的番茄抗旱性。检查SlNCED1/4启动子中预测结合位点上游的2-kb序列，确定了SlNCED1/4启动子中核心W-box（TTGACC/T）序列的两个拷贝，这与这些基因的表达密切相关响应干旱，进一步表明ABA依赖性途径参与SlWRKY6诱导的抗旱性。该研究揭示了SlWRKY6的关键作用，该研究有助于进一步揭示干旱机制和抗旱番茄品种的选育，以实现气候变化时代的可持续蔬菜生产。
