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Genetic Diversity Of Paris Polyphylla Var. Yunnanensis Detected By ISSR Markers

Posted on:2008-02-04Degree:MasterType:Thesis
Country:ChinaCandidate:J HeFull Text:PDF
GTID:2120360215987799Subject:Botany
Abstract/Summary:PDF Full Text Request
In present study, we use ISSR markers to investigate the level and distribution ofgenetic diversity of P. polyphylla var. yunnanensis. Our aims are to provideelementary information for understanding the genetic diversity of P. polyphylla var.yunnanensis, and for proposing practical utilization for this important medicinalplant.Fourteen primers were screened from 113 ISSR primers, which were used toinvestigate the genetic diversity of 6 populations of P. polyphylla var. yunnanensis. Atotal of 251 bands were resulted, of which 227 were polymorphic. At the species level,the genetic diversity were PPB=90.44%, HE=0.201, HO=0.325; at the populationlevel, the genetic diversity were PPB=53.31%, HE=0.152, HO=0.238, which show ahigh level of genetic diversity of P. polyphylla var. yunnanensis.For the natural populations of P. polyphylla var. yunnanensis, at the populationlevel, the genetic diversity was low (HE=0.151, HO=0.235), and the percentage ofpolymorphic bands (PPB) per population ranged from 46.61% to 59.76% with anaverage of 53.38%; at the species level, the genetic diversity was relatively high(PPB=76.89%, HE=0.187, HO=0.298). The special breeding system, morphologicaland physiological after-ripening, tremendously population fragmentation in the wildcaused by excessively excavated and its habitat fragmentation may be the mainreasons for this results. The genetic diversity of among the natural populations wasrelatively higher than that within the populations which correlated to themorphological diversity of different P. polyphylla var. yunnanensis populations.The coefficient of genetic differentiation (GST) among the natural populationsdetected by POPGENE was 0.1952, out of accord with the result by AMOVA revealed(FST=0.312), suggested that 19.52 % of the total variation was partitioned amongpopulations, genetic variation mainly existed within population. The breeding system,mating system and seed twice-dormancy may be limit the gene flow, and then lead tothe genetic differentiation among populations.The genetic diversity of cultivated populations was relatively higher than that of the natural populations. At the species level, PPB=83.27%, HE=0.186, HO=0.302; Atthe population level, PPB=57.24%, HE=0.153, HO=0.241. It may be explained bythe fact of recent introduction, comparatively wide areas of origin and artificialselection of the cultivation from different sources of origin. A UPGMA dendrogramwas reconstructed based on the Nei's genetic distance. In total, two major clusterswere identified. Population DL and the three natural populations formed a clade,cultivated populations LJ and WD formed another one. It was also a reflection thatgenetic differentiation between the natural populations and the cultivated populationswas not obvious. It was different that the genetic diversity of each cultivatedpopulation (HE=0.140~0.167). WD source has the lowest genetic diversity, evenlower than that of the natural populations LP and SM (HE=0.156), only equal to HLpopulation. Consequently, it is indispensable to introduce more wild individuals, suchas populations SM and LP, to retain as much genetic diversity as possible.In general, the physiological characters of the seeds and tremendously habitatfragmentation may be the main reasons that lead to the low genetic diversity of thenatural populations of P. polyphylla var. yunnanensis.
Keywords/Search Tags:Paris polyphylla var.yunnanensis, ISSR, genetic diversity, natural populations, cultivated populations, fragmentation
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