Ozone and aging up-regulate type II metacaspase gene expression and global metacaspase activity in the leaves of field-grown maize (Zea mays L.) plants

Rafiq Ahmad (1) , Yasmine Zuily-Fodil (1) , Chantal Passaquet (1) , Olivier Bethenod (2) , Romain Roche (2) , Anne Repellin (1)

1 IBIOS
2 EGC - Environnement et Grandes Cultures

Maize plants (Zea mays L. cv. NK Perform) were exposed to O3-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 metacaspasespecific synthetic tripeptide Boc-GRR-AMC. Aging had little effect on mRNA accumulation whereas four to six-fold increases were observed for the most O3-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 O3 and age-mediated senescence.

Mots clés: type II metacaspases; Zea mays L.; RT-qPCR; global metacaspase activities; tropospheric O3

Mots clés: Zea mays L

Domaines: Milieux et Changements globaux

Rafiq Ahmad, Yasmine Zuily-Fodil, Chantal Passaquet, Olivier Bethenod, Romain Roche, et al.. Ozone and aging up-regulate type II metacaspase gene expression and global metacaspase activity in the leaves of field-grown maize (Zea mays L.) plants. Chemosphere, 2012, 87 (7), pp.789-795. ⟨10.1016/j.chemosphere.2011.12.081⟩. ⟨hal-01003248⟩