Study On Population Genetic Structure Of Cymbidium Kanran Makino From Jiangxi Based On ITS And CpDNA Molecular Marker

Orchidaceae is the most evolved species in angiosperms and one of the bigfamilies which have the most abundant species, Most of them are the rare andendangered plants of the world. Cymbidium kanran Makino the Cymbidium(Orchidaceae), with high ornamental value and economic value. Jiangxi province issurrounded by mountain, the territory of wild C. kanran Makino resources are veryrich. However the over-excavation、tree felling and forest fire make the naturalhabitat has been seriously damaged. and the number of C. kanran Makinodrastically reduced.In this research, Survey the wild population of C. kanran Makino from fourmountains of Jiangxi: Jiulian mountain, Wuyi mountain, Jiuling mountain andLuoxiao mountain.and collected250individuals from17populations, Use the ITSand cpDNA molecular markers to analyzed the population genetic structure, geneticdiversity, phylogeography and gene flow characteristics, Base on this theoreticalresult to find out the reason of the rare of wild C. kanran Makino, To provide moreinformation and advices for the protection and rational use of it. The main results asfollows.（1）The total length of ITS sequence in C.kanran Makino range is652bp to658p, The length of ITS1range from240bp to241bp, the length of5.8S is163bpand the length of ITS2range from245bp to253bp. The content of G+C in totalsequence, ITS1,5.8S and ITS2respectively range from58.9%to67.1%, from56.5%to68.1%, from54.3%to62.4%and from59.7%to72.6%. The content of G+C ishigher in each region, The ITS sequences have140variable sites and117parsimonyinformative sites. There are10kinds of ITS types in250samples from17populations of wild C. kanran Makino, including16populations containing twokinds of ITS types (T2is the most widely distributed), especially Wuyi containedthe most abundant ITS type, There are eight types. By AMOVA analysis of ITSsequence revealed genetic variation among populations was21.12%, according tothe genetic variation within the group was69.24%, indicating a high degree of genetic differentiation among populations inside, the door to the degree of geneticdifferentiation between populations is relatively low. Nm=1.1428, Nm>1,indicates C. kanran Makino of Jiangxi has high levels of gene flow between thevarious populations.（2）Wild C. kanran Makino of Jiangxi cpDNA, the total length of petB-petDsequence range is522-529bp, content of G+C range from32.9%-33.7%, Weredetected in nine variable sites and five parsimony informative sites. Populationgenetic diversity showed that: In the17C. kanran Makino populations there aretotal of11haplotypes, which Hap4is the widespread lineage haplotypes,15populations contain two kinds or more haplotypes, indicating that the populationshave haplotype. Luoxiao and Jiulian Mountains have three haplotypes, JiulingMountains have four haplotypes, Wuyi Mountains contains seven haplotypes. ByTCS mesh structure Hap4haplotype is the most original figure speculated; throughHAPLONST analysis, the coefficient of genetic differentiation among populationsof Gst=0.413, Nst=0.472, using the U test of17populations of C. kanran Makinopedigree geographical structure analyzed, UNst/Gst=1.08<U0.05=1.96, P>0.05, indicates C. kanran Makino populations no obvious pedigree geographicalstructure. For17populations of wild C. kanran Makino correlation analysis ofgenetic and geographic distances by IBD, showed no significant correlation betweenthe two (r=0.0121, p=0.5720), indicates the degree of genetic differentiationamong populations C. kanran Makino not because the distance caused bygeographical distance. cpDNA sequence analysis of variance (AMOVA) showedthat genetic variation among populations kanran was40.13%, genetic variationwithin populations was49.28%, the degree of genetic differentiation withinpopulations greater than the genetic differentiation among populations, Nm=0.7839, Nm<0.99, indicate wild C. kanran Makino of Jiangxi has medium levels ofgene flow between the various populations..(3) Through a comprehensive analysis of ITS and cpDNA data, Jiangxi17wild populations of C. kanran Makino overaall high level of genetic diversity,genetic differentiation at population is much higher than the internal geneticdifferentiation among populations, indicating that the major mountains gene flow between different populations greater. The genetic diversity of wild C. kanranMakino population of Wuyi is the most abundant, Luoxiao followed, the other twomountains are less. In the17C. kanran Makino populations, AF and SW twopopulations have the highest level of genetic differentiation, and the highestmaximum ITS types and haplotype species. Probably because both of them arelocated in the provinces of edge effects at the junction of the mountains, making thelevel of gene flow among populations higher, and the two have established aNational Nature Reserve, a good surrounding environment, human disturbance areless.By studying the results of this experiment combine the actual situation of thesurvey sampling strategy for resource protection and development of Jiangxi wild C.kanran Makino use the following recommendations: First, for the rich geneticdiversity of a larger number such as AF, SW, ZX, SC, TG, YF and JGS takenestablishment of nature reserves and other places, and set up to supervise the site inthe surrounding situ conservation; second, the low genetic diversity of wild C. kanranMakino drastically reduced the number and distribution of JA, LN, LC, NF, AY, CYand other places to take a combination of artificial introduction and rapid propagationtechniques “return” technology to restore local populations of wild C. kanran Makinoscale as soon as possible; third, increased research efforts to find better ways tomaintain and expand population size and the number of wild C. kanran Makino, andprotect their pollinators.