Analysis Of Phylogenetic Relationship Of Four Ecotypes Reed (Phragmites Communis Trin.) From Hexi Corridor In Gansu Province In China Based On CpDNA Sequences

There are four ecotypes reed (Phragmites communis Trin.) growing in Badanjilin desert in Hexi corridor for a great many years. The have abundant distinct difference in morphology, physiology-biochemical, bionomics and anatomy. Predecessors have sorted them and named them with swamp reed(SR), light salt meadow reed(LSMR), heavy salt meadow reed(HSMR) and dune reed(DR) respectively according to general factors in physiology-biochemical and habitat. And the corresponding environment of them is morass about 1m deep, border of salt meadow and dune, downfold covered with obvious salt and dune about 2-10m in height. This paper aims at analysing of the phylogenetic relationship of the four ecotypes on the basis of prevenient research, using PCR (Polymerase Chain Reaction) technology to amplify and sequence the three following regions - trnL-F, rpL16 and matK/trnK - of chloroplast genome. MEGA 4.0 and PAUP4b10 are used for studying sequence analysis and systematically reconstruction. The results are as follows:(1) trnL-F, rpL16 and matK/trnK all belong to chloroplast genome (cpDNA). The overall mean genetic distance of trnL-F is 0.028, the coefficient differentiation and mean interpopulation diversity of it is 0.556 and 0.015 respectively. The same index of rpL16 are 0.028, 0.648 and 0.018 while of matK/trnK are 0.023, 0.588 and 0.013. Partition homogeneity test for evaluating the reliability of three-region combined data analysis is performed and the diversity among them is not significant, indicating that the three regions could be analysed as whole. The overall mean genetic distance of three-region combined data is 0.028, the coefficient differentiation is 0.609 and mean interpopulation diversity is 0.017.(2) Phylogenetic relationship of the four ecotypes is calculated withMaximum Likelihood method(ML), Maximum Parsimony method(MP)and Neighbor—Joining method(NJ). And the tree styles are not identical when different method is used, but the results of classify are similar, samples of one ecotype could be gathered and separated with other genre.(3) The findings which shows SR is the oldest and genetic relationship of the four ecotypes from near to far based on each sequence and combined data analysis is: the nearest distance is between SR and LSMR sequentially is LSMR and HSMR, HSMR and SR, HSMR and DR, LSMR and DR, and the farthest is between SR and DR. Therefore we could speculate that in the process of evolution, the tendancy from SR via salt meadow reed to DR.(4) The findings based on each sequence and combined data analysis also shows that genetic diversity exist among samples belong to the same ecotypes, especially in LSMR and HSMR, the diversity value are over 0.010; moreover, in HSMR is 0.017; While SR and DR have less diversity among their samples, less than 0.010, particularly in DR, only 0.005, so samples of DR have been classfied into one sort with 100% bootstrap value. Consequently, it is concluded LSMR and HSMR are intergradation of reed's evolvement, with a high variation; SR and DR have developed each steady population.In conclusion, applying chloroplast genome for phylogenetic research of reed in hungriness of Hexi corridor is effective. Finally, we nominate SR as the original ecotype, and they develop various mutations in the process of adjusting to drought-prone and saline habitat, these mutations include morphological, physiological, cellular and molecular and so on and pass down steadily, hence the three different ecotypes formed.