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Genetic Diversity Of Plants Of Genus Kobresia In The East Of Qinghai-Tibet Plateau

Posted on:2007-10-30Degree:DoctorType:Dissertation
Country:ChinaCandidate:Q F ZhaoFull Text:PDF
GTID:1100360212456444Subject:Ecology
Abstract/Summary:PDF Full Text Request
Kobresia species are perennial herb and distribute mainly in the Qinghai-Tibet plateau. The Kobresia are dominant species in alpine meadows of the Qinghai-Tibet plateau and adjacent areas, and are an important forage grass of high economic as well as ecological value. Kobresia species have the characteristics of soft texture and nutrition nourishing and play a important role in retaining the ecological environment of Qinghai-Tibet plateau. Because of the limitatios in sampling and the variability in morphology, the study f genetic diversity of Kobresia have not been done. This study investigated the genetic diversity of Kobresia species collected from the eastern Qinghai-Tibet plateau in China, using RAPD markers, characteristics of comparative anatomy of leaves, and molecular phylogeny. The main results are as follows:1. The genetic diversity of five Kobresia plants, K.humilis, K.royleana, K.kansuensis, K.tibetica and K.setchwanens were investigated using RAPD markers. A totle of 23 populations, 484 individules were amplified. Out of 250 oligonucleotide primers initially screened, 14 primers were chosen that together generated 179-194 loci, and 138-168 loci were polymorphic. The five species all showed high genetic diversity, with values for mean percentage polymorphic loci, PPB 58.06%-71.13%; mean Nei's gene diversity, h 0.1997-0.2521; mean Shannon's Information index I 0.2998-0.3772 at the population level. At the species level, percentage polymorphic loci, PPB was 76.67%-87.70%; Nei's gene diversity, h was 0.2527-0.3106; Shannon's Information index I was 0.3805-0.4628. In five species, AMOVA showed that most of the genetic variability (77.45%-89.06%) resided among individuals within populations, whereas only a minor part (10.94%-22.55%) resided among populations. The Gst-values (0.1066-0.2101) showed the similar result. Among the five species, K.royleana (Nm=4.1906,Gst=0.1066) and K.kansuensis (Nm=2.9766,Gst=0.1438)had the greater gene flow and the genetic differentiation were lower. K.setchwanensis (Nm=1.8801, Gst=0.2101) had the lowest gene flow and the genetic differentiation was the greatest.Based on the above results, it could obtain the below conclusions: (1) the Kobresia...
Keywords/Search Tags:Genetic diversity, Genetic structure, Qinhai-Tibet Plateau, RAPD maker, Comparative anatomy, Molecular Phylogeny, Clustering analysis, Phylogenetic significance
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