Growth, photosynthesis and podophyllotoxin accumulation of Dysosma versipellis in response to a light gradient and conservation implications

Dysosma versipellis (Hance) M. Cheng ex Ying (Berberidaceae) is a rare and vulnerable, perennial herb endemic to China with pharmaceutical significance. Increasing habitat loss and over-exploitation of the plant has severely affected the plant’s in situ conservation, necessitating ex situ conservation and commercial cultivation. The light regime is a critical environmental factor contributing to successful ex situ conservation via efficient production of biomass and secondary metabolites. We investigated the responses of 2-year-old D. versipellis plants to a light gradient in terms of leaf morphology, growth, biomass production, photosynthesis and podophyllotoxin (PTOX) accumulation. D. versipellis responded to the light gradient in terms of plant height, leaf size, leaf photosynthesis and PTOX accumulation. Plants demonstrated optimal vegetative growth, photosynthetic capability, and PTOX production, under a light intensity equal to 30% full sunlight. Half full sunlight led to the lowest production of PTOX despite having no obviously different effects on growth. Full sunlight was able to cause leaf death in mid-summer (July), although these plantlets did not significantly differ in growth or biomass production before July and new leaves emerged in August. D. versipellis is therefore proposed to be a shade-tolerant plant, well adapted to variations in irradiance. Irradiance of 10%–50%, particularly ca. 30% full sunlight is strongly recommended for ex situ conservation and commercial cultivation.