Abstract:

Many pine trees of Sect. Pinus are distributed throughout China, and are important species for afforestation in China. Seeds and seedlings of these closely related species are similar in morphological characters. It is difficult to identify them according to their morphology. Seeds and seedlings from 11 pine species were identified by integrating their different morphological characters of seeds (1 000-seeds weight, seeds shape and color) and seedlings (number of cotyledon, color of hypocotyls and seedling height), with their ISSR and SSR markers. At the same time, genetic relationship between those closely related species was assessed based on information from SSR markers. The results showed that P. tabulaeformis and P. caribaea were easily distinguished from 11 pine species according to morphological differences of seeds and seedlings, and 10 of 11 species were identified accurately based on ISSR and SSR markers. However, no species-specific primer (loci) was found to recognize P. densata because of its complicated genetic background. Genetic relationship between 10 pine species based on 41 polymorphic loci amplified by 5 pairs SSR primers was similar with relationship of traditional taxonomic groups. UPGMA dendrogram demonstrated that 3 taxonomical groups were clustered at the similarity coefficient of 0.6. The first group consisted of P. massoniana and P. densiflora . The second group had 6 species which further were divided into two sub-groups, with one sub-group including P. yunnanensis , P. kesiya , P. densata and P. tabulaeformis ; the other sub-group including P. thunbergii and P. sylvestris . The last group contained P. taeda and P. caribaea , and they had relatively distant relationship from other two groups, with the similarity coefficient of 0.42.

Key words: Pinus, morphological character, ISSR, SSR, identification, genetic relationship