Molecular Evolution Of Wild And Cultivated Barley In China, And Molecular Mapping Of New Gene For Earbranching Trait In Barley

Molecular evolution and mapping of genes are important contents in the study of molecular biology. The excavation, study and use of special germplasm resources are major subjects in crop genetics and breeding. Bax\ey(Hordeum vulgare L.), one of the most important and oldest cultivated crops, and also one of the important economic crops and model crops in genetic study, has long been an extensive concern of researchers in crop genetics and breeding, plant physiology and molecular biology. China is one of the centers of origin of barley, and earbranching trait is crucial target to be seeked in high yield breeding of barley. Therefore, the studies on evolution of wild and cultivated barley in China, and also mapping of genes for earbranching trait of barley in molecular level are significant in both theory and practice.I. Molecular evolution of wild and cultivated barley in ChinaTwo-rowed wild barley (H. vulgare ssp. spontaneum, HS), bottle-shaped wild barley(H. vulgare ssp. agriocrithon var. lagunculiforme,HL) and six-rowed wild barley(H. vulgare ssp. agriocrithon, HA) are widely distributed in Tibet of China, which is center of origin of Chinese cultivated barley. Naked. barley, also calledQingke, is ingredient of Zanba-the major food of Zang-nationality peopie inhabited on the Qinghai-Xizang plateau of China which is known as the "roof of the world". Six-rowed naked cultivated barley was first cultivated in China. Which is the progenitor of Chinese cultivated barley, two-rowed wild barley or six-rowed wild barley? How did cultivated barley in China spread? Microsatellite markers (simple sequence repeats, SSR) are of many advantages. As second-generation molecular markers and better markers in the study of population genetic variation, they have been widely used in the construction of molecular genetic map, genetic diversity, germplasm identification, gene mapping, molecular marker-assisted selection and origin and evolution, and so on. Evidently, using microsatellite markers in the study of the above issues will prove helpful in elaborating origin and evolution of Chinese cultivated barley, protecting and efficiently using genetic resources. Major results are as follows:1. Evolutionary relationships and genetic differentiation of three groups of wild barley in Tibet using SSR markers106 accessions of wild barley collected from 6 regions(cities) of Tibet, including 50 entries of HS, 29 entries of HA and 27 entries of HL, were analyzed with 35 SSR markers selected from different locations on two arms of each of barley linkage map published by Liu et al.(1996) for the study of genetic diversity and genetic differentiation of three groups of the Tibetan wild barley. The results showed that significant genetic differentiation in both genetic compositions and allelic frequencies distribution among the three grorps of wild barley were existed. 7.6 alleles per SSR locus were detected in entire sample. Total number of alleles showed significant difference among the three groups of wild barley. The evolutionary relationship is HS-HL-HA, indicating that two-rowed wild barley is progenitor of Chinese cultivated barley, six-rowed wild barley is an intermediate form in transforming from two-rowed wild barley to cultivated barley, and also supporting the theory of two-rowed wild barley monophyletic origin for as cultivated barley. From these results and previous studies, six-rowed wild barley might be originated from hybrids.2. Genetic diversity and geographical differentiation of two-rowed wildbarley in Tibet using SSR markersGenetic diversity and geographical differentiation of 50 accessions of the two-rowed wild barley from different regions of Tibet using 35 SSR markers from different locations of 7 barley linkage groups were studied. The results showed that, SSRs had higher ratio(97.44%) of polymorphism fragments; 1-14 alleles of each SSR locus were detected with an average of 4.04 alleles/locus; The highest averages of both genetic diversity and alleles(0.4933 and 3.35, respectively) occurred in Shannan region of Tibet;...