Plant Molecular Biology & Proteomics Lab, Institute of Biotechnology, Hangzhou Academy of Agricultural Sciences, Hangzhou 310024, PR China.
BMC Plant Biol. 2011 Feb 16;11:34. doi: 10.1186/1471-2229-11-34.
High Salinity is a major environmental stress influencing growth and development of rice. Comparative proteomic analysis of hybrid rice shoot proteins from Shanyou 10 seedlings, a salt-tolerant hybrid variety, and Liangyoupeijiu seedlings, a salt-sensitive hybrid variety, was performed to identify new components involved in salt-stress signaling.
Phenotypic analysis of one protein that was upregulated during salt-induced stress, cyclophilin 2 (OsCYP2), indicated that OsCYP2 transgenic rice seedlings had better tolerance to salt stress than did wild-type seedlings. Interestingly, wild-type seedlings exhibited a marked reduction in maximal photochemical efficiency under salt stress, whereas no such change was observed for OsCYP2-transgenic seedlings. OsCYP2-transgenic seedlings had lower levels of lipid peroxidation products and higher activities of antioxidant enzymes than wild-type seedlings. Spatiotemporal expression analysis of OsCYP2 showed that it could be induced by salt stress in both Shanyou 10 and Liangyoupeijiu seedlings, but Shanyou 10 seedlings showed higher OsCYP2 expression levels. Moreover, circadian rhythm expression of OsCYP2 in Shanyou 10 seedlings occurred earlier than in Liangyoupeijiu seedlings. Treatment with PEG, heat, or ABA induced OsCYP2 expression in Shanyou 10 seedlings but inhibited its expression in Liangyoupeijiu seedlings. Cold stress inhibited OsCYP2 expression in Shanyou 10 and Liangyoupeijiu seedlings. In addition, OsCYP2 was strongly expressed in shoots but rarely in roots in two rice hybrid varieties.
Together, these data suggest that OsCYP2 may act as a key regulator that controls ROS level by modulating activities of antioxidant enzymes at translation level. OsCYP2 expression is not only induced by salt stress, but also regulated by circadian rhythm. Moreover, OsCYP2 is also likely to act as a key component that is involved in signal pathways of other types of stresses-PEG, heat, cold, or ABA.
高盐度是影响水稻生长和发育的主要环境胁迫因素。为了鉴定新的参与盐胁迫信号转导的成分，对耐盐杂交品种汕优 10 幼苗和盐敏感杂交品种两优培九幼苗的杂交水稻 Shoot 蛋白进行了比较蛋白质组学分析。
在盐诱导胁迫过程中上调的一种蛋白质（环孢菌素 2（OsCYP2））的表型分析表明，OsCYP2 转基因水稻幼苗对盐胁迫的耐受性强于野生型幼苗。有趣的是，野生型幼苗在盐胁迫下最大光化学效率明显降低，而 OsCYP2 转基因幼苗则没有观察到这种变化。OsCYP2 转基因幼苗的脂质过氧化产物水平较低，抗氧化酶活性较高。OsCYP2 的时空表达分析表明，它可以在汕优 10 和两优培九幼苗中被盐胁迫诱导，但汕优 10 幼苗的 OsCYP2 表达水平较高。此外，汕优 10 幼苗中 OsCYP2 的昼夜节律表达比两优培九幼苗更早发生。PEG、热或 ABA 处理诱导汕优 10 幼苗中 OsCYP2 的表达，但抑制两优培九幼苗中 OsCYP2 的表达。冷胁迫抑制汕优 10 和两优培九幼苗中 OsCYP2 的表达。此外，OsCYP2 在两种水稻杂交品种的茎中强烈表达，但在根中很少表达。
综上所述，这些数据表明，OsCYP2 可能作为一个关键的调节剂，通过调节抗氧化酶的活性来控制 ROS 水平。OsCYP2 的表达不仅受到盐胁迫的诱导，还受到昼夜节律的调节。此外，OsCYP2 还可能作为一个关键成分，参与其他类型胁迫（PEG、热、冷或 ABA）的信号通路。
