ABSTRACT. Dahurian larch (Larix gmelinii), a deciduous conifer, is the northernmost tree, native to eastern Siberia and nearby regions of China. We used growth traits and molecular markers to assess genetic variation in different L. gmelinii growing regions; 105 individual samples were collected from seven regions of the Qingshan Forestry Centre, Heilongjiang Province, China. The greatest genetic regional variation was seen in the Youhao area, based on coefficients of variation for tree height, diameter and volume (14.73, 28.25, and 55.27%, respectively). Analysis using molecular markers showed rich genetic diversity. The RAPD and ISSR methods both indicated that most variation came from within populations. The seven regions were divided into two groups (Daxing'an and Xiaoxing'an Mountain ranges) by RAPD cluster analysis: Tianchi, Xiaojiuya, Yuanjiang, and Taiping regions were placed in the first group at a genetic distance of 0.08; while the other regions were in the second group. The correlation : 196-207 (2013) Genetic diversity of Larix gmelinii between RAPD markers and geographical distance was significant, with a correlation coefficient of 0.752.

ABSTRACT. Toona sinensis Roem has an important value as a type of traditional vegetable and Chinese medicinal herb, and is also a valuable source of wood in China. In this study, we used the inter-simple sequence repeat (ISSR) and sequence-related amplified polymorphism (SRAP) markers to assess the level and pattern of genetic diversity in five domesticated T. sinensis populations in China. Our results indicated a relatively low level of genetic diversity both at species (Hs = 0.1662, 0.2098, respectively) and population levels (Hs = 0.0978, 0.1145, respectively). Molecular variance analyses revealed a relatively high degree of differentiation among populations (G ST = 0.3901, 0.4498), and low levels of gene flow (N m = 0.7816 and 0.6116). We divided the five populations into two groups by cluster analysis: group one consists of populations collected from the south part of China (e.g., Yuxi, Yunan Province and Zuanjiang, Chongqing Municipality), and group two contains those cultivated in north part of China (e.g., Hengshui, Hebei Province, Jinan and Rizhao, Shandong Province). The correlation of genetic relationships among populations fits well with their geographical distribution (Mantel test; r = 0.7236 and 0.6789, respectively). Asexual propagation, limited gene flow and geographic isolation are most likely the key factors associated with the observed genetic structure of T. sinensis grown in China. The present study indicated that both ISSR and SRAP markers were effective and reliable for assessing the degree of T. sinensis genetic variations.