Aalysis Of Genetic Variation Of Wheat Landrace 'Xiaohongmang'

Wheat (Triticum aestivum L.) is one of the most important crops in China. Due to repeated use of the same parental genotypes in modern breeding programs, genetic diversity in wheat cultivars has been narrowed, which limits further improvement of wheat against biotic and abiotic stresses. It is, therefore, important to broaden genetic diversity in wheat cultivars. During the long history of wheat cultivation, a large number of wheat landraces had been developed in China, which were characterized by high heterogeneity. It is important to study the genetic diversity and genetic variation of wheat landrace, which could provide rationale for collection preservation, application and protection of wheat landrace and provide evidence for wheat evolutionary history in China.In this study, genetic diversity and genetic variation of wheat landraces that originated from seven different wheat growth regions of China were analyzed using morphology data, high molecular weight glutenin subunit (HMW-GS), VRN-A1 promoter region and disease resistance analysis, respectively. The results were as follows:1 The results of clustering and diversity analysis based on morphology data indicate that the materials in the present study derived from one variety. Previous studies had indicated that the diversity centre of cultivated plants are always the origin centre or where the variety introduced earlier. The diversity analysis in the present study shows that the diversity index of accessions from spring wheat growth areas were higher than that from winter wheat growth areas, which indicated that"Xiaohongmang"and"Xiaohongmangmai"were initially grown in spring wheat growth area and then introduced to winter wheat growth area.2 The HMW-GS analysis showed the same trend as in morphology analysis. The genetic diversity of accessions from spring wheat growth areas is higher than that from winter wheat growth areas. Further more, accessions from northwest spring wheat growth areas and northern spring wheat growth areas possess not only the highest genetic diversity, but also a rich source of variation. Especially the accessions from Gansu Tianzhu in northwest spring wheat growth areas show the highest genetic diversity among all the accessions. The geographic location of Gansu Tianzhu facilitates the spread of crops. Gansu Tianzhu area may be the origin center of"Xiaohongmang"and"Xiaohongmangmai".3 11-bp indel were observed in the VRN-A1 promoter region adjacent to the CArG-box, which was proved to be associated with the spring growth habit of wheat in previous studies. The CArG-box is a common binding site for MADS-box protein which was a kind of transcription factor. It indicated that this site might be involved in the regulation of VRN-A1gene. Polymorphism analysis of VRN-A1 shows the same results as morphology and HMW-GS study that"Xiaohongmang"and"Xiaohongmangmai"spread from spring wheat growth area to winter wheat growth area.4 The results of disease resistance identification and polymorphism analysis showed the same trends of genetic variation as morphology, HMW-GS and VRN-A1 analysis that"Xiaohongmang"spread from spring wheat growth area to winter wheat growth area.There were some germplasms showing resistance to these disease,like ZM002008 and ZM002697 were high resistant to three physiological races(CY31, CY32, Su-14) of stripe rust, ZM000247, whereas ZM001902, ZM002026 and ZM002593 were completely immune to two physiological races (E09, HN-1) of powdery mildew.