Responses in the morphology, physiology and biochemistry of Taxus chinensis var. mairei grown under supplementary UV-B radiation.

The effects of supplemental UV-B radiation on Taxus chinensis var. mairei were studied. Leaf traits, gas exchange parameters and the concentrations of photosynthetic pigments, cellular defense system products, secondary metabolites and ultrastructure were determined. UV-B radiation significantly decreased leaf area (p<0.05). Leaf number, secondary branch number, leaf weight per plant and leaf moisture all increased dramatically (p<0.05). Neither the leaf weight nor the specific leaf weight (SLW) exhibited significant differences between ambient and enhanced UV-B radiation. Gas exchange parameters were all dramatically reduced by enhanced UV-B radiation (p<0.05). The contents of chlorophyll and the chlorophyll a/b ratio were not distinctly affected by UV-B radiation, while carotenoids content significantly decreased (p<0.05). Supplemental UV-B treatment induced significant flavonoid accumulation (p<0.05), which was able to protect plant from radiation damage. Meanwhile, the appendage content, abaxial stomatal density, papilla density and particulate matter content in substomatic chambers increased noticeably by supplemental UV-B radiation, whereas the aperture size of single stomata was diminished. The number and area of plastoglobuli were apparently reduced by UV-B radiation, but stroma and grana lamellae were not destroyed. Our results demonstrated that T. chinensis var. mairei can activate several defense mechanisms against oxidative stress injury caused by supplemental UV-B radiation.

[Quantitative changes of anti-cancer active components in Taxus chinensis var. mairei branches and leaves].

The quantitative changes of anti-cancer ingredients such as taxol, cephalomannine, baccatin III and 10-deacetylbaccatin III in the branches and leaves of Taxus chinensis var. mairei during one growth season were measured by HPLC. The results showed that the contents of these anticancer ingredients had an obvious change from April when the new branches began to germinate to November when the branches basically stopped growing. The contents of taxol and cephalomannine in the branches and leaves of T. chinensis had the same change pattern, with the peaks appeared in May, and those of Baccatin III and 10-deacetylbaccatin III had the same change trend, with the highest values appeared in September and April, respectively. There was a significant positive correlation between the contents of taxol and cephalomannine (P <0.05), and a negative correlation between the contents of cephalomannine and 10-deacetylbaccatin III (P <0.05).