Equipe IBIOS, UMR 7618 Bioemco, Université Paris Est-Créteil, 61 Avenue du Général de Gaulle, 94010 Créteil Cedex, France.
Chemosphere. 2012 May;87(7):789-95. doi: 10.1016/j.chemosphere.2011.12.081. Epub 2012 Jan 25.
Maize plants (Zea mays L. cv. NK Perform) were exposed to O(3)-enriched air, using a new field fumigation system. Transcriptional changes for three type II-metacaspase genes were studied in the leaves (ranks 10 and 12), using quantitative real-time PCR. Global metacaspase activity was measured using metacaspase-specific synthetic tripeptide Boc-GRR-AMC. Aging had little effect on mRNA accumulation whereas four to six-fold increases were observed for the most O(3)-responsive type II metacaspase genes, in the older leaves 10. Global metacaspase activity increased by 257% and 333% in leaves 12 and 10, respectively, in response to the highest cumulated concentration. In non-fumigated plants, metacaspase activity progressively increased over the course of the experiment and always was higher in the older leaves 10. Together, these results suggest that metacaspase-mediated proteolysis is a crucial step in leaf responses to both O(3) and age-mediated senescence.
玉米植株（Zea mays L. cv. NK Perform）在一种新的田间熏气系统中暴露于富含 O3 的空气中。使用定量实时 PCR 研究了叶片（第 10 和 12 级）中三种 II 型半胱天冬酶基因的转录变化。使用半胱天冬酶特异性合成三肽 Boc-GRR-AMC 测量全局半胱天冬酶活性。衰老对 mRNA 积累几乎没有影响，而在较老的叶片 10 中，最易受 O3 响应的 II 型半胱天冬酶基因的表达增加了四到六倍。在叶片 12 和 10 中，全局半胱天冬酶活性分别增加了 257%和 333%，以响应最高累积浓度。在未熏气的植物中，半胱天冬酶活性在实验过程中逐渐增加，并且在较老的叶片 10 中总是更高。这些结果表明，半胱天冬酶介导的蛋白水解是叶片对 O3 和年龄介导的衰老的反应的关键步骤。
