Studies On Genetic Diversity And Systematic Status In Rare And Endangered Plant Prunus Mongolica

Prunus mongolica(Rosaceae subfamily Prunoideae) is aperennial desert xeric shrub native to the Mongolian Plateau. It is an ancient relict plant that mainly grows in extreme environments, such as on low mountains and hills, on stony slopes, and in dry beds in the desert and desert steppe regions. P. mongolica has distinct xeromorphic adaptations, such as hard shoot spines at the ends of the branchlets. At present, there are some debates in the academia about P. monglica is Amygdalus, Prunus or Amygdalus L. Because the shrubs are limited by environmental conditions, P. mongolica cannot form large desert populations; it is only found scattered in the mountains and gullies. Such habitat fragmentation may influence the genetic diversity and evolutionary potential of the species. In this study, we analyzed the genetic diversity of six P. mongolica populations in Inner Mongolia using inter-simple sequence repeat (ISSR) markers. We analyzed the genetic diversity and genetic structure of different natural populations of P. mongolica, in order to elucidate the adaptive mechanisms and evolutionary potential of P. mongolica in arid and nutrient-poor environments and to provide data for its effective protection. Meanwhile, the r DNA ITS sequence and trnL-F sequences of/P· mongolica by DNA sequencing were obtained and aligned from the r DNA ITS sequences and trnL-F sequences of some plants which obtained from GenBank of Prunus, Amygdalus and constructed the dendrogram. Molecular evidences were provided to study the Taxonomic Status of P. mongolica. The results were as follows:1.12primers were screened out from74UBC ISSR primers which was the good polymorphism and repeating primer with clear bands. The primers are contains (AG)nand (GA)n except UBC842.2.12ISSR primers amplified200DNA fragments, of which199(99.5%) showed polymorphisms among the populations. The size of amplified fragments could be scored ranged from200-2000bp. The percentage of polymorphic banded at the population level ranged from43%(Hohhot Wuyishuiku population) to67%(Baotou Slaqi population)3. No obvious difference was found by Nei’s analysis in different populations(F=0.861, P>0.05), the result showed that P. mongolica had little differences in different populations. Nei’s and Shannon’s had the same trend in different populations, that is BS>HY>WQ>DN>AB>HW, but Shannon’s was higher than Nei’s.4. The results indicated that total gene diversity of the six populations(Ht) was0.3241, gene diversity within the populations was0.2019, coefficient of genetic differentiation among the populations was0.3769, genetic aberrance among the populations accounted for37.69%of the total population aberrance, the aberrance was from within the populations. The gene flow (Nm=0.8266<1) between P. mongolica population obtained by gene differentiation coefficient, it shows that has lower gene flow in different populations.5. The results of molecular phylogenetic tree by Neighbor-Joining (NJ) and maximum likelihood (ML) with r DNA ITS sequence and trnL-F sequence shows that P. mongolica had near relationships with Prunus than Amygdalus.