We analysed the cellular and molecular changes in the leaf growth zone of tolerant and sensitive rice varieties in response to suboptimal temperatures. Cold reduced the final leaf length by 35% and 51% in tolerant and sensitive varieties, respectively. Tolerant lines exhibited a smaller reduction of the leaf elongation rate and greater compensation by an increased duration of leaf growth. Kinematic analysis showed that cold reduced cell production in the meristem and the expansion rate in the elongation zone, but the latter was compensated for by a doubling of the duration of cell expansion. We performed iTRAQ proteome analysis on proliferating and expanding parts of the leaf growth zone. We identified 559 and 542 proteins, of which 163 and 210 were differentially expressed between zones, and 96 and 68 between treatments, in the tolerant and sensitive lines, respectively. The categories protein biosynthesis and redox homeostasis were significantly overrepresented in the up-regulated proteins. We therefore measured redox metabolites and enzyme activities in the leaf growth zone, demonstrating that tolerance of rice lines to suboptimal temperatures correlates with the ability to up-regulate enzymatic antioxidants in the meristem and non-enzymatic antioxidants in the elongation zone.

中文翻译：

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水稻叶片生长区的氧化还原稳态在耐寒性中起关键作用。

我们分析了耐温和敏感水稻品种叶片生长区中细胞和分子的变化，以适应最适度的温度。寒冷使耐性和敏感品种的最终叶片长度分别减少了35％和51％。耐性品系表现出较小的叶片伸长率降低幅度，并通过增加叶片的生长时间获得更大的补偿。运动学分析表明，冷降低了分生组织中的细胞产量，降低了伸长区中的扩增速率，但后者却因细胞扩增持续时间加倍而得到了补偿。我们对叶片生长区域的增殖和扩展部分进行了iTRAQ蛋白质组分析。我们鉴定出559和542种蛋白质，其中163和210在区域之间差异表达，在处理之间96和68差异表达，分别在宽容和敏感线上。在上调的蛋白质中，蛋白质生物合成和氧化还原稳态的类别明显过高。因此，我们测量了叶片生长区中的氧化还原代谢产物和酶活性，表明水稻品系对最适温度的耐受性与上调分生组织中酶抗氧化剂和延伸区中非酶抗氧化剂的能力有关。