Study On Genetic Structure Of Tamarix Chinensis In Natural Populations In Yellow River Delta

In this paper genetic diversity and population genetic structure of 3 natural populations of Tamarix chinensis, one of the main predominated forests in Yellow River Delta, were studied by means of random amplified polymorphic DNA (RAPD) markers. Based on the research of population genetic structure strategies, the conservation of these germplasm resources of T.chinensis were also discussed. The main results are highlighted in the following:A total of 150 individuals representing 3 natural populations of T. chinensis, were surveyed by use of 26 RAPD primers from 700, which generated 262 reproducible and clear amplification products. A relatively high level genetic diversity was detected in T. chinensis species. Out of 262, 105 loci with molecular weight from 200 to 2200 were polymorphic and accounted for 39.31%. Nei's gene diversity (h) and Shannon diversity index (I) were 0.4061 and 0.5917 in the species lever, respectively. Strong adoption, low environment select pressure and relatively few human activities might be the causes of high genetic diversity of T .chinensis.Coefficient of genetic differentiation (Gst) generated by POPGENE was 0.0507. AMOVA showed that only 7.17% of the genetic diversity resulted from differentiation among populations with remaining 92.83% residing within populations. That showed the majority of genetic variation occurred within populations and the high level of gene flow was among populations. Continued distribution, long life, predominantly outcrossing , strong reproduction and high flow gene might be the main causes of low genetic differentiation of T.chinensis populations.101 simple sequence repeats (SSRs) from 5030 T. ramosissima expressed sequence tags (ESTs) were identified and characterized. Dinucleotide repeats and trinucleotide repeats accounted for 37.6% and 29.7% of the total EST-SSRs, respectively. 10 of these potential EST-SSRs were selected for primer design. Of these 10 primer pairs, 2 were co-dominant and polymorphic, 3 were monomorphic and 5 were not amplified among T.chinensis. Our results indicate that these EST-SSR markers from T. ramosissima EST database are potentially useful tools for studying genetics in T.chinensis.The effect of the number of sampled individuals on population genetic structure parameters was surveyed. As RAPD markers revealed, the sampling numbers of population had some effect on some parameters which measured population genetic diversity, such as A, h etc. even if only 30 individuals were sampled from every population. While several differential parameters such as Gst, Nm, were greatly effected by the number of sampled...