Analysis Of Genetic Diversity Of Hordein In Wild Close Relatives Of Barley From Tibet

The role of Tibetan wild close relatives of barley in the research about the origin and evolution of the word barley is very important. They also are the precious germplasm resources for genetic breeding. In this report, we analyzed the genetic diversity in the storage protein hordein encoded at Hor-1, Hor-2 and Hor-3 loci in seeds from 211 accessions of wild close relatives of barley from Tibet, which includs 123 accessions of H. vulgare ssp. agriocrithon (HA) and 88 accessions of H, vulgare ssp. spontaneum (HS). The results were as follow.1 , Altogether 32, 27 and 13 different phenotypes were found for Hor-1, Hor-2 and Hor-3 respectively. A comparison of our results with those of previous studies indicates that Tibetan samples reflect the highest diverse level of hordein phenotypes when compared to samples from Israel and Jordan. This high degree of polymorphism supports the hypothesis that Tibet is one of the original centers of H. vulgare L2, The genetic diversity value of each locus was calculated for each of the two barley groups. The order for the value was HS < HA for Hor-2 locus, and HA < HS for the other two loci. When with an average of the three loci, the value of HA waslower than HS (1.802 to 1.906).3 , Partitioning of the diversity value showed that the proportion of genetic diversity accounted for by differentiation among groups was generally small. It varied from a low of 3.99% at the Hor-2 locus to a high of 9.03% at the Hor-3 locus, with an average of 6.65%.Barley as a crop grown in the Qinghai-Tibet Plateau (including the upper reaches of the Yellow River) had been in agriculture records 3000 years B.C. , indicating that barley in this region has an ancient history. Also, this region is geographically isolated from the rest of the world by several of the world's largest mountain ranges. Our study demonstrates large amount of genetic variation in wild barley from Tibet. Thus, further supports the hypothesis that the Qinghai-Tibet Plateau and its vicinity are the center of origin for the cultivated barley in the Oriental region.We did not include accessions of HV from Tibet and HS from Southwest Asia in the present study. To access the relative levels of genetic diversity among the barley group in Tibet, further studies using the three barley groups - HS, HA and HV - from Tibet are definitely needed. Studies on phylogenetic relationships among the barley groups and between HS from Tibet and Southwest Asia will also be needed.