Relationship between leaf reddening, ROS and antioxidants in Buxus microphylla during overwintering
2016
Jiang, Xue-ru | Peng, Jin-gen | Jia, Meng-xue | Liu, Yan | Guo, Ling | Gao, Rong-fu
To provide a theoretical basis for revealing the mechanism of winter leaf reddening in evergreen species, the relationships between winter leaf reddening, reactive oxygen species (ROS) and the antioxidant system of Buxus microphylla ‘Wintergreen’ were studied. The pigment changes, ROS production, lipid peroxidation and antioxidants activities of sun leaves during the reddening and regreening processes were investigated, using green shade leaves as controls. The carotenoids in the sun leaves increased linearly with reddening but decreased with the regreening. There was no significant difference in either the superoxide anions (O ₂ ⁻·) or malondialdehyde (MDA) changes between the sun and shade leaves, and their O ₂ ⁻· contents were positively correlated with MDA. In contrast to the shade leaves, the sun leaves showed a trend in which the hydrogen peroxide (H₂O₂) changes were closely related to the reddening process and positively correlated with carotenoids content but not with the MDA content. A similar trend was observed for catalase (CAT) and ascorbate peroxidase (APX) activity between the sun and shade leaves, but superoxide dismutase (SOD) and peroxidase (POD) activity and the ascorbate (AsA) content differed between these two ecotypes. Furthermore, the sun leaves had higher CAT activity and AsA content than the corresponding shade leaves. These results suggested that H₂O₂ might play an important role in the winter reddening of sun leaves by promoting the accumulation of carotenoids. In addition, SOD, POD and AsA probably play a photoprotective role in winter-red sun leaves, while the changes in O ₂ ⁻· , CAT and APX were independent of winter leaf reddening and were more likely responses to stress caused by low temperatures.
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