Enhanced antioxidant protection at the early stages of leaf expansion in ginkgo under natural environmental conditions

• Published in: Biologia plantarum Vol. 56; no. 1; pp. 181 - 186
• Main Authors: Yang, X. -S., Chen, G. -X., Wei, X. -D., Xie, K. -B.
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01.03.2012; Institute of Experimental Botany of the Czech Academy of Sciences
• Subjects: ascorbate peroxidase; Biomedical and Life Sciences; Brief Communication; carotenoids; catalase; chlorophyll fluorescence; chloroplast ultrastructure; ginkgo biloba; Life Sciences; net photosynthetic rate; peroxidase; Plant Sciences; superoxide dismutase; net photosynthetic rate; ascorbate peroxidase; carotenoids; peroxidase; chlorophyll fluorescence; superoxide dismutase; catalase; chloroplast ultrastructure
• ISSN: 0006-3134; 1573-8264
• DOI: 10.1007/s10535-012-0039-9

Photosynthetic pigments, gas exchange, chlorophyll (Chl) a fluorescence kinetics, antioxidant enzymes and chloroplast ultrastructure were investigated in ginkgo ( Ginkgo biloba L.) leaves from emergence to full size. Under natural conditions, the net photosynthetic rate (P N ), contents of Chl a , Chl b and total soluble proteins and fresh and dry leaf mass gradually increased during leaf expansion. The maximum photochemical efficiency of photosystem (PS) 2 (variable to maximum fluorescence ratio, F v /F m ) was considerably higher at the early stages of leaf development than in fully expanded leaves. During daily course, only reversible decrease in F v /F m was distinguished at various stages, implying that no photo-damage occurred. Absorption flux per cross section (CS) and trapped energy flux per CS were significantly lower in newly expanding leaves compared with fully expanded ones, however, dissipated energy flux per CS was only slightly lower in expanding leaves. The ratio of carotenoids (Car)/Chl decreased gradually during leaf expansion due to increasing Chl content. Moreover, activities of the antioxidant enzymes, such as superoxide dismutase, ascorbate peroxidase, catalase and peroxidase, increased at the early stages of leaf expansion. The appearance of osmiophilic granules in fully expanded leaves further proves that photo-protection is significantly strengthened at the early stages of leaf expansion.