Molecular Phylogenetic Analysis And Core Collection Construction Using SSR And AFLP Markers In Pummelo

China is one of the main original and genetic variation centers of pummelo (Citrus grandis (L.) Osbeck), in which germplasm resources are very abundant. Because of its monoembryo characteristic, pummelo has formed very abundant genetic diversity through long term evolvement under the complicated environment. At present, only a little of the evolvement connection and the phylogenetic relationships among pummelo germplasms had been known. Especially, we know nothing about the construction of pummelo core collection. In this study, we collected many varieties from important pummelo producing areas in our country and worked on construction for DNA fingerprints of main pummelo varieties, genetic diversity of pummelo germplasms, construction of pummelo core collection, which provided more evidences for origin, classification, breeding, germplasms conservation of pummelo. The main results were as follows:1. 31 SSR and 3 AFLP pairs of primers were used to research the genetic diversity of 122 pummelo germplasms and theirs relatives. Total of 335 alleles and 9.85 alleles per SSR loci were identified by 31 pairs of SSR primers. The average value of allelic polymorphism information content (PIC) of SSR was 0.7085. 57 unique bands were scored from 15 pummelo germplasms and theirs relatives; 72% of the 343 alleles which produced by 3 pairs of AFLP primer were polymorphic at 5% level, 114 alleles and 82 polymorphic loci per primer were identified. The average Heterozygosity per primer was 0.2445, and 44 AFLP unique bands were scored from 15 genotypes.2. The feasible number of SSR loci in identification of pummelo germplasms and theirs relatives was confirmed. 21 pairs of SSR primer of high PIC which were very good fit to 31 pairs of primer in genetic relationship of 122 pummelo germplasms was selected(r=0.9910). Finally, we selected 9 pairs of primer which has the highest PIC as core SSR primers.These primers of high PIC can be used to research the citrus and its relatives directly by different department.3. The genetic variance of pummelo germplasms and theirs relatives was analyzed by SSR marker. In the 122 pummelo germplasms and theirs relatives, 'Oroblanco' had the highest average allele number.(3.6), the smallest one was 'Citrus mangsh-anensis' (1.7) and theirs average value was 2.8 only; the percentage of heterotic loci ranged from 53.8 %( 'Citrus mangshanensis') to 96.8 %( 'Edanyou'), and theirs average value was 83.54%; the average direct count heterozygosity of SSR was 0.524. Hybrid and other pummelo group had the highest percentage of heterotic loci (85.5%) and direct count heterozygosity (0.540), following with 'shatianyou' group (85.2%, 0.535) and 'Wendan'group (83.0%, 0.514), the smallest was pummelo relatives group (72.5%, 0.464).4. The genetic diversity of ecological distribution of our country was analyzed. 92 pummelo varieties were divided into 6 groups according to the direction of mountains and rivers. Total Heterozygosity of 92 varieties was 0.2431, in which Heterozygosity within groups was 0.227, Heterozygosity between groups was 0.0161, and Wright's fixation index (Fst) within groups was 0.0667. The...