Physiological response of rare and endangered seven-son-flower (Heptacodium miconioides) to light stress under habitat fragmentation

Seven-son flower (Heptacodium miconioide) is a prized, useful and well-accepted landscape plant in North America and some European countries but only grows in East China. Unfortunately, the distribution region, population size and individual numbers of seven-son flower rapidly decrease in the wild. It is a particular rare, highly severe endangered and protective plant. Here we investigated the physiological responses of seven-son flower at eight different sites under fragmental habitats in the Beishan mountains (Zhejiang, China), one of two only areas where the communities of seven-son flower currently are discovered. This was to determine the effect of light stress under fragmental habitat on the physiology and to explore the endangering mechanism of seven-son flower. The study shows that strong light brought by habitat fragmentation obviously inhibited the photosynthesis rates reduced antioxidant enzymes (superoxide dismutase (SOD), catalase (CAT), peroxidase (POD) and ascorbate peroxidase (APX)) activities and promoted electrical conductivity and MDA content of seven-son flower leaves. The characteristics of leaves were also affected by light intensity in fragmental habitat. Intense light in fragmental habitat is disadvantageous to photosynthesis and antioxidant enzymes of the flower. Our results suggest that biodiversity conservation of seven-son flower is timely needed and the light intensity should be considered carefully when biodiversity conservation of seven-son flower to be carried out, especially in the transplant conservation of seven-son flower from deteriorative area in the wild.