Antioxidative response of Golden Agave leaves with different degrees of variegation under high light exposure

Variegated mutants are spotted rare in wild, and especially in the high light (HL) conditions. In addition, these plants are cultivated by a growing number of horticulturists due to their high economic value. In this experiment, the antioxidative response of both albino and green tissues from a mutant plant Golden Agave, which possesses leaves with different degrees of variegation, was investigated under normal or HL exposure, respectively. Severe oxidative stress was observed in green tissues of high albinism leaves (30-40 % albino tissues, muy) over low albinism counterparts (less than 10 % albino tissues, mug). Compared with green tissues, low oxidative damage (relative electrolyte leakage and protein damage) and antioxidant enzyme (SOD, CAT, APX, and GR) activities were observed in the albino than in the adjacent green tissues. Photoinactivation of the CAT and the APX enzyme activities were observed in the albino tissues to a significantly level under HL exposure. In addition, lower redox values (ASC/DHA and GSH/GSSG) and higher levels of reactive oxygen species (ROS) were monitored in the green tissues of the muy over mug mutant even under normal light conditions. This work could help us to understand the HL sensitivity of variegated mutant plants better and allow us to improve variegated mutant plant cultivation skills. At last, the oxidative stress hypothesis was introduced to illustrate the reduced evolutionary advantage of plant variegation phenomenon in the discussion.