Study On The Genetic Diversity Of Kmeria Septentrionalis Dandy

Kmeria septentrionalis Dandy, an endemic genus to China, belongs to the family Magnoliaceae, which are listed among GradeⅠNational Protected Rare and Endangered Plants. In China, Kmeria septentrionalis Dandy mainly grows wild in the southwestern region (Mulun Huangjiang and Luocheng Guangxi Province, Maolao libo Guizhou Province,Maguan Yunnan Province ) .Magnoliaceae is one of the most primative angiosperm , Kmeria septentrionalis Dandy is triecious which is a especial species in the evolution of Magnoliaceae, it has very high value in scientific research. At the same time, it grows quickly as good timber so it is valuable and significance in forestry and research.。According to the distribution of Kmeria septentrionalis Dandy, thirteen populations are sampled (eight populations from Mulun, Huangjiang,Guangxi, two populations from Luocheng, Guangxi, three populations from Maolan , Libo, Guizhou). Genetic diversity and genetic structure of Kmeria septentrionalis Dandy were investigated by using amplified fragment length polymorphism (AFLP) markers. An understanding of both genetic diversity and genetic structure of Kmeria septentrionalis Dandy provides insight for the conservation and management of this endangered species . The main results were as follows:1. Amplified results:A total of 6 AFLP primer combinations were employed on 260 individuals of Kmeria septentrionalis Dandy from 96 primer combinations. These primers generated a total of 317 bands, of which 157 were polymorphic.2. Genetic diversityAt species level, the percentage of polymorphic loci (P) was 49.53%, Nei's gene diversity (He) was 0.1289, and Shannon's information index (I) was 0.2004, respectively. At population level, the estimates of P =31.13%(27.76%～35.02%),He =0.1063(0.0967～0.1203),I =0.1594(0.1442～0.1807). Among 13 populations, CD revealed higher variability (P =35.02%,He =0.1203,I =0.1807),whereas DHN revealed the lowest variability (P =27.76%,He =0.0969, I =0.1442). Compare with other endangered woody dicotyledon, the genetic diversity of natural Kmeria septentrionalis Dandy is low.3. Genetic structureThe coeffient of genetic differentiation among populations (Gst) was 0.1748, suggesting that 17.48% of the total genetic diversity was distributed among populations, it indicated conspicuous genetic differentiation within populations. Analysis of molecular variance (AMOVA) furter revealed that 3.43% of the AFLP variance resided between region (MulunMaolan and luocheng),14.6% among population and 81.97% within populations. Average gene flow (Nm =2.3608) was moderate,it may revealed that higher frequency existed in Kmeria septentrionalis Dandy. The result of AMOVA analysis basically complied with the results of gene differentiation coefficient analysis.4. Genetic distanceThe means of genetic distance among population were 0.0294(0.0111～0.0379), which is lower.In addition, UPGMA map were made according to the genetic distance of the thirteen populations calculated in this article. It has been shown according to cluster dendrogram that the 13 natural Kmeria septentrionalis Dandy populations can be divided into two big groups i.e first group from Mulun, Huangjiang, Guangxi and Maolan, Libo, Guizho; second group from Luocheng,Guangxi. Therefore, we can divide it into two provenance regions. Results of clustering analysis showed a complied trend between each cluster group and geographical difference.The correlation coefficient (r) between genetic and geographical distance using Mantel's test for all populations was 0.44786 (P=0.0010). It revealed that the genetic distances among the populations might be unconspicuous relation to their geographic locations. A conclusion can be drawn that there are low genetic diversities in the thirteen natural populations of Kmeria septentrionalis.They may relate to the poor regeneration ability caused by innate biological and ecological characteristics and the environmental damage to natural populations.Based upon the above-mentioned results, more strict conservation management should include both in situ conservation and ex situ conservation programs and need to be well designed.First, as the genetic diversity of thirteen natural Kmeria septentrionalis Dandy populations are close from the population level ,we proposed some appropriate strategies for conserving the endangered species in original place; namely, conserving the core populations CD,KD,BN and LD for in situ conservation. A human-aided regeneration is proposed to protect and restore populations.Also, the sampling strategy for conservation, ex situ: sampling five populations CD, KD, BN, LD and RM with more individuals for each population. We need to take the rate of survive for this specie into account, as well as the relative fitness . Base upon the valid protection and recovery of the endangered specie, utilizing these resources with reason through the introduction of seeds or seedling and artificial implantation were considered.