Plant Gene Research Center, National Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China.
Plant J. 2010 Apr;62(2):316-29. doi: 10.1111/j.1365-313X.2010.04146.x. Epub 2010 Jan 27.
Receptor-like kinases (RLKs) play essential roles in plant growth, development and responses to environmental stresses. A putative RLK gene, OsSIK1, with extracellular leucine-rich repeats was cloned and characterized in rice (Oryza sativa). OsSIK1 exhibits kinase activity in the presence of Mn(2+), and the OsSIK1 kinase domain has the ability to autophosphorylate and phosphorylate myelin basic protein (MBP). OsSIK1 promoter-GUS analysis revealed that OsSIK1 is expressed mainly in the stem and spikelet in rice. The expression of OsSIK1 is mainly induced by salt, drought and H(2)O(2) treatments. Transgenic rice plants with overexpression of OsSIK1 show higher tolerance to salt and drought stresses than control plants. On the contrary, the knock-out mutants sik1-1 and sik1-2, as well as RNA interference (RNAi) plants, are sensitive to drought and salt stresses. The activities of peroxidase, superoxide dismutase and catalase are enhanced significantly in OsSIK1-overexpressing plants. Also, the accumulation of H(2)O(2) in leaves of OsSIK1-overexpressing plants is much less than that of the mutants, RNAi plants and control plants, as measured by 3,3'-diamino benzidine (DAB) staining. We also show that OsSIK1 affects stomatal density in the abaxial and adaxial leaf epidermis of rice. These results indicate that OsSIK1 plays important roles in salt and drought stress tolerance in rice, through the activation of the antioxidative system.
类受体激酶（RLKs）在植物生长、发育和对环境胁迫的响应中发挥着重要作用。在水稻（Oryza sativa）中克隆并鉴定了一个具有细胞外亮氨酸丰富重复的假定 RLK 基因 OsSIK1。OsSIK1 在存在 Mn2+的情况下表现出激酶活性，并且 OsSIK1 激酶结构域具有自身磷酸化和磷酸化髓鞘碱性蛋白（MBP）的能力。OsSIK1 启动子-GUS 分析表明，OsSIK1 在水稻中的茎和小穗中表达主要。OsSIK1 的表达主要受盐、干旱和 H2O2 处理诱导。过表达 OsSIK1 的转基因水稻植株比对照植株对盐和干旱胁迫具有更高的耐受性。相反，敲除突变体 sik1-1 和 sik1-2 以及 RNAi 植株对干旱和盐胁迫敏感。过表达 OsSIK1 的植株中过氧化物酶、超氧化物歧化酶和过氧化氢酶的活性显著增强。此外，通过 3,3'-二氨基联苯胺（DAB）染色测量，过表达 OsSIK1 的植株叶片中 H2O2 的积累量明显少于突变体、RNAi 植株和对照植株。我们还表明，OsSIK1 影响水稻叶片背腹表皮的气孔密度。这些结果表明，OsSIK1 通过激活抗氧化系统在水稻的耐盐和耐旱性中发挥重要作用。
