Chin J Plant Ecol ›› 2008, Vol. 32 ›› Issue (5): 985-993.DOI: 10.3773/j.issn.1005-264x.2008.05.002

• Original article • Previous Articles     Next Articles

SEASONAL CHANGES IN THE FOLIAR ANTIOXIDANT SYSTEMS IN CYCLOBALANOPSIS HELFERIANA AND TERMINTHIA PANICULATA IN THE HOT-DRY VALLEY OF THE YUANJIANG RIVER, CHINA

ZHU Jun-Jie1,2, CAO Kun-Fang1,*()   

  1. 1Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Kunming 666303, China
    2Graduate University of Chinese Academy of Sciences, Beijing 100049, China
  • Received:2007-09-10 Accepted:2008-03-21 Online:2008-09-10 Published:2008-09-30
  • Contact: CAO Kun-Fang

Abstract:

Aims Hot-dry valleys in southwestern China are adverse habitats. The foliar antioxidant system of plants growing there must play an important role in protecting their photosynthetic apparatus against photo-oxidation. Our aim was to characterize the responses of the antioxidant system to seasonal changes of multiple abiotic stresses in two dominant tree species in the hot-dry valley of the Yuanjiang River, Yunnan.

Methods We chose two savanna species with different photosynthetic rates for study: the evergreen Cyclobalanopsis helferiana(oak) and drought-deciduous Terminthia paniculata(sumach). We examined changes of the two main antioxidants, ascorbate (ASC) and glutathione contents and the activities of all of the antioxidant enzymes of the water-water and ASC-glutathione cycle in these two species from the hot-rainy season to the chill-dry season and to the warm-dry season.

Important findings Both species showed the highest antioxidant activity in the chill-dry season; however, they had the highest activities of glutathione transferase and glutathione peroxidase in the subsequent warm-dry season. They had similar ASC and glutathione contents and activity of SOD, the initial enzyme of water-water cycle, but sumach displayed higher activities of most antioxidant enzymes in the water-water and ASC-glutathione cycles in all seasons compared to oak. Overall, sumach activated its antioxidant system more actively than oak, yet oak had more persistent antioxidant activity than sumach. Compared with activities of antioxidant systems of plants growing in other adverse conditions, the two study species have stronger antioxidant capacity, which is consistent with their absolutely lower contents of malondialdehyde in all seasons.

Key words: chilling, drought, multiple stresses, photo-oxidation