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Pak. J. Bot., 42(1): 117-127, 2010.

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AFLP ANALYSIS OF GENETIC DIVERSITY IN POPULUS CATHAYANA REHD ORIGINATING FROM SOUTHEASTERN QINGHAI-TIBETAN PLATEAU OF CHINA

KE CHEN¹ AND YOUHONG PENG^2*

Abstract: The wide geographical and climatic distribution of Populus cathayana Rehd indicates that there is a large amount of genetic diversity available, which can be exploited for conservation, breeding programs and afforestation schemes. In our study, genetic diversity was evaluated in the natural populations of P. cathayana originating from southern and eastern areas of the Qinghai-Tibetan Plateau of China by means of AFLP markers. For four primer combinations, a total of 175 bands were obtained of which 173 (98.9%) were polymorphic. Six natural populations of P. cathayana possessed different levels of genetic diversity, high level of genetic differentiation existed among the populations (G_ST=0.489) of P. cathayana. Individuals cluster and PCO analysis based on Jaccard’s similarity coefficient also showed evident population genetic structure with high level of population genetic differentiation. The long evolutionary process coupled with genetic drift within populations, rather than contemporary gene flow, are the major forces shaping genetic structure of P. cathayana populations. Moreover, there was no correspondence between geographical and genetic distances in the populations of P. cathayana, seldom gene exchange among the populations and different selection pressures may be the causes. Our findings of different levels of genetic diversity within populations and high level of genetic differentiation among the populations provided promising condition for further breeding and conservation programs.

¹School of Life Science and Engineering, Southwest University of Science & Technology, Mianyang 621010, China

²Chengdu Institute of Biology, Chinese Academy of Sciences, P.O.Box 416, Chengdu 610041, China