The WRKY transcription factor family is involved in responding to biotic and abiotic stresses. Its members contain a typical WRKY domain and can regulate plant physiological responses by binding to W-boxes in the promoter regions of downstream target genes. We identified the sweet sorghum SbWRKY50 (Sb09g005700) gene, which encodes a typical class II of the WRKY family protein that localizes to the nucleus and has transcriptional activation activity. The expression of SbWRKY50 in sweet sorghum was reduced by salt stress, and its ectopic expression reduced the salt tolerance of Arabidopsis thaliana plants. Compared with the wild type, the germination rate, root length, biomass and potassium ion content of SbWRKY50 over-expression plants decreased significantly under salt-stress conditions, while the hydrogen peroxide, superoxide anion and sodium ion contents increased. Real-time PCR results showed that the expression levels of AtSOS1, AtHKT1 and genes related to osmotic and oxidative stresses in over-expression strains decreased under salt-stress conditions. Luciferase complementation imaging and yeast one-hybrid assays confirmed that SbWRKY50 could directly bind to the upstream promoter of the SOS1 gene in A. thaliana. However, in sweet sorghum, SbWRKY50 could directly bind to the upstream promoters of SOS1 and HKT1. These results suggest that the new WRKY transcription factor SbWRKY50 participates in plant salt response by controlling ion homeostasis. However, the regulatory mechanisms are different in sweet sorghum and Arabidopsis, which may explain their different salt tolerance levels. The data provide information that can be applied to genetically modifying salt tolerance in different crop varieties.

中文翻译：

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甜高粱SbWRKY50通过调节离子稳态而负参与盐反应。

WRKY转录因子家族参与对生物和非生物胁迫的反应。它的成员包含一个典型的WRKY结构域，可以通过结合下游靶基因启动子区域的W-boxs来调节植物的生理反应。我们确定了甜高粱SbWRKY50（Sb09g005700）基因，该基因编码WRKY家族蛋白的典型II类，该蛋白定位于细胞核并具有转录激活活性。盐胁迫降低了甜高粱中SbWRKY50的表达，其异位表达降低了拟南芥植物的耐盐性。与野生型相比，盐胁迫条件下SbWRKY50过表达植物的发芽率，根长，生物量和钾离子含量显着下降，而过氧化氢，超氧阴离子和钠离子含量增加。实时PCR结果表明，在盐胁迫条件下，过表达菌株中AtSOS1，AtHKT1及与渗透压和氧化胁迫相关基因的表达水平降低。萤光素酶互补成像和酵母一杂交试验证实，SbWRKY50可以直接结合拟南芥中SOS1基因的上游启动子。然而，在甜高粱中，SbWRKY50可以直接结合SOS1和HKT1的上游启动子。这些结果表明，新的WRKY转录因子SbWRKY50通过控制离子稳态来参与植物盐反应。然而，甜高粱和拟南芥的调节机制不同，这可能解释了它们对盐的耐受性水平不同。