Genetic Diversity And Population Structure Of Camellia Nitidissima As Revealed By ISSR,RAPD And AFLP Markers

Camellia nitidissima Ch(iTheaceae), is a very famous ornamental plant honored as "The Queen of Camellia"for having yellow, waxy and shiny petals. It is an germplasm for the breeding of yellow camelliain and has been introduced into Japan, Australia and North America. Analysis about C. nitidissima on taxonomy, geographic distribution and mophology have developed to a in-depth level, whereas the conservative work of C. nitidissima is lack of the supporting of the theoretical guidance on genetic diversity research. This study selected 120 individuals of 6 populations of C. nitidissima which distrubuted in Guangxi, China and adopted ISSR, RAPD and AFLP as the molecular markers to detect the genetic diversity and the genetic variation, genetic structure between and within the two distribution region , among and within the populations. An understanding of both genetic diversity and population structure of C. nitidissima provides insight for the conservation and management of this endangered species. This study get to the conclusion thereinafter: 1. The genetic diversity of C. nitidissima revealed by ISSR RAPD, and AFLP on species level:( The average percentage of polymorphic bands (P) was 75.2% for ISSR, 79.7% for RAPD and 80.73% for AFLP respectively. The Nei's genetic diversity index (H) was 0.2302 for ISSR, 0.2685 for RAPD and 0.2547 for AFLP. The Shannon diversity information index (I) was 0.3504 for ISSR, 0.4042 for RAPD and 0.3885 for AFLP. All of these three molecular markers are the suitable one to test the genetic diversity of C. nitidissima. 2. The genetic variation among the natural populations of C. nitidissima revealed by Nei's analysis and Analysis of Molecular Variation showed the significant genetic differentiation had occurred between populations. Genetic variation mainly existed between populations(Gst: 0.5752 for ISSR , 0.6140 for RAPD and 0.4950 for AFLP).Gene flow between 6 populations was 0.4439, less than 1, indicating limited genetic intercourse. Nevertherless, the gene flow between the CF and CH populations in Nanning distributing area was 1.6450, the one between CN, CJ, CL and CD 4 populations in Fangcheng distributing area was 0.8000, showing there is still some genetic intercourse within the two distributing area of C. nitidissima. Of all the 120 individuals, the individuals from a population can cluster together in the dendrogram based on genetic similarity. Mantel test also showed a positive correlation (r=0.9399, p=0.0490<0.05)existed between genetic distance and geographical distance. This genetic structure might owe to the disturbance of gene flow caused by fragmentation of habitat. 3. In general, the natural populations of C. nitidissima can survive in nature as long as they are kept from interference. So as many as possible the natural populations of C.nitidissima should be conserverd in situ is advised. The populations in the region of Nanning area march with Fushui and Chongzuo need the further conservation.