Study On Genetic Diversity Of A Rare And Endangered Plant Camellia Luteoflora Li Ex H.T.Chang

Camellia luteoflora Li ex H.T.Chang,a perennial evergreen woody plant,belongs to the camellia,Sect.Luteoflora,in the Theaceae family,which is a rare and endangered plant in China,it's mainly distributed in the narrow area of Jinshagou,Sidonggou,Chishui,Guizhou Province and Guihua Town,Gulin County,Sichuan Province.In recent years,with the expansion of the asexual propagation of bamboos around the C.luteoflora population and the fragmentation of the original habitat,the population size and the number of individuals show a sharp trend of decrease,and the species become endangered.So,it has become an urgent task to carry out the investigation,assessment and protection of this unique and rare species in China.In this study,based on the existing wild populations of C.luteoflora,two new distribution sites of C.luteoflora were found,covering all the distribution sites of C.luteoflora.The phenotypic variation,genetic diversity and their correlation with environmental factors were studied in 10 small C.luteoflora populations in Guizhou and Sichuan Province.Combining with morphological,ecological and genetic methods,the main contents were phenotypic variation,population genetic variation marked by ISSR,phenotypic and genetic diversity and their relationship with environmental factors.The purpose of this study is to provide a theoretical basis for the effective protection and rational utilization of C.luteoflora germplasm resources.The study results are as follows:(1)From the morphological point of view,18 phenotypic characters of the leaf and flower were analyzed systematically.Among the phenotypic characters,except for the diameter of outer stamen filament,the length of stamen and the number of attached calyx,the other 15 phenotypic characters had significant or extremely significant differences among the populations.The variation range of each character of C.luteoflora is 1.65%-37.04%,the average variation coefficient(CV)is 10.22%,the mean variation of vegetative organ is 12.08% more than that of reproductive organ 8.74%.The mean value of Vst was 33.78%,and the variation of Vst within populations was 66.22%.The variation within the population was the main source of the phenotypic variation.Principal Component Analysis showed that leaf width,leaf area,petiole length,leaf length and leaf perimeter played a major role in population variation.There was significant or extremely significant correlation between most phenotypic traits.Clustering analysis can cluster 10 C.luteoflora populations into two major groups,and cluster results tend to cluster into one with higher habitat similarity,such as Xiahegou,Guanyinyan and Wadianzi,which are clustered into one,all of which are distributed in the valley with lower altitude.(2)The results of ISSR marker analysis showed that 107 loci were amplified by 13 ISSR primers,of which 97 were polymorphic,the percentage of polymorphic bands(P)was 90.65%,the number of alleles(Na)was 1.6204,the number of effective alleles(Ne)was 1.4164,the Nei's diversity index(H)was 0.2353,and the Shannon's information index(I)was 0.3460.The information content of genetic diversity was rich in 10 populations,H ranged from 0.1847 to 0.2726,I ranged from 0.2719 to 0.4036.In general,the genetic diversity of Wadianzi population and Chentian population is the highest,while that of Shigangyan population is the lowest.The total genetic diversity(Ht)of C.luteoflora is 0.3170,the genetic diversity(Hs)in the population is 0.2353,and the gene differentiation coefficient(Gst)is 0.2538,which indicates that 25.38% of the genetic variation exists in the population,74.62% of the variation exists in the population,and which is consistent with the results of phenotypic differentiation research.The gene flow(Nm)among populations was 1.5623,indicating that there was little gene exchange and low level of gene differentiation among populations.The genetic consistency coefficient of 10 populations is 0.8331-0.9329,the genetic distance is 0.0703-0.1906,indicating that the genetic similarity of each population is high.Based on the results of UPGMA cluster analysis,the populations of Sichuan and Guizhou were separated and distributed in a certain area.The results of 88 individuals clustering alone do not strictly follow the geographical distribution,and the individuals in the same population tend to gather together,which indicates that there may be small patch island distribution in the individuals in the population,and there may be a certain amount of gene flow among the individuals in the population.(3)The genetic similarity analysis based on using 13 primers was carried out on the clustering of 26 materials of C.luteoflora and some collected Camellia plants by ISSR marker analysis.The results showed that the distance between C.luteoflora and C.yunnanensis var.trichodarpa and C.petelotii was relatively close.(4)Based on the correlation analysis of 11 environmental factors with phenotype and genetic diversity,it was found that latitude,slope,interference intensity,soil AP and soil AK were significantly or extremely correlated with some phenotypic traits,and the difference of these five factors was one of the reasons for the formation of the diversity of C.luteoflora;slope and effective allele number(Ne)were significantly negative,there was no significant correlation between other environmental factors and genetic diversity parameters.(5)There are two main reasons for the endangered of C.luteoflora,firstly,the invasion of Phyllostachys pubescens and the fragmentation of habitat lead to the decline of the suitable range of population,and the human interference leads to the gradual decline of population into patchy distribution;secondly,the gene exchange between populations is blocked,resulting in the low level of gene differentiation among populations,reducing the evolutionary potential of populations.In view of the current situation,and combined with the above research results,the following protection strategies are suggested: 1)investigate and study C.luteoflora suffering from diseases and insect pests and declining growth,find out the causes and carry out appropriate pruning and treatment;2)properly clean up the populations greatly affected by Phyllostachys edulis to promote the regeneration of C.luteoflora;3)for the populations with rich phenotypic and genetic variation(such as Wadianzi,Chentian),We should pay attention to the collection and Strengthen protect germplasm resources,and take it as a priority to protect populations.4)The growth and protection status of C.luteoflora germplasm resources were monitored.