Ozone tolerance in Phaseolus vulgaris depends on more than one mechanism

摘要

Two bean cultivars with different sensitivity to ozone, i.e. the 03-sensitive Cannellino and the 03-tolerant Top Crop, were exposed to acute O_3-stress (165 nL L~(-1)) with the aim of evaluating physiological and biochemical traits that may confer O_3-tolerance. Stomatal conductance was smaller and the ability to dissipate excess energy, via regulated and unregulated nonphotochemical quenching mechanisms was greater in Top Crop than in Cannellino. These morphological and physiological-traits allowed the O_3-tolerant cultivar to compensate for the light-induced declines in Φ_(PSII), to preserve photosystem II from excitation-energy, and likely to prevent the generation of ROS to a superior degree than the O_3-sensitive cultivar. Furthermore, the potential capacities to reducing the superoxide anion and H_2O_2 were significantly greater in Top Crop than in Cannellino. These findings are consistent with the early accumulation of H_2O_2, the almost complete disruption of cell structure, and irreversible damages to the photosynthetic apparatus observed in the O_3-sensitive cultivar.