Abstract: Ormosia hosiei is an endangered and precious timber species in South China. Its wood is a top-grade material for furniture, ornament, and sculpture. By using ISSR molecular markers, the genetic diversity and differentiation of five naturally reserved O. hosiei populations in Zhejiang and Fujian provinces were investigated. The results showed thatO. hosiei had a high degree of genetic diversity. The percentage of its polymorphic loci was 91.46%, and the total gene diversity was 0.3981, being significantly higher than those of the other rare and endangered species. Although the five naturally reserved populations were smaller in size, they had a higher level of genetic diversity, with the percentage of population polymorphic loci, Nei’s genetic diversity, and Shannon’s information diversity index being 81.71%-89.02%, 0.3498-0.3831 and 0.5026-0.5506, respectively. The existing populations were all old stands that reserved after excessive deforestation, and the genetic differentiation between these populations was small because of short fragmented time. Molecular variance analysis demonstrated that the among-population and within-population component accounted for 6.45% and 93.55% of the total genetic variation, respectively. Naturally reserved O. hosiei populations with larger size had higher genetic diversity, which would be protected with priority.

Key words: Gynostemma pentaphyllum, Transpiration rate, Stoma conductance, Photon flux density, Net photosynthetic rate