The The Malus Xiaojinensis Genetic Diversity Apf1 Of Gene Cloning, Sequence Analysis And Genetic Transformation Research

Mains Miller belongs to sub-family Maloidae of Rosaceae family in plant taxonomy. There were thirty to thirty-five recognized species of the genus in the world, which distributed mainly in Asia, Europe and North America from subtropical to tropical mountainous areas in the world. Among them twenty to twenty-three, at least, were found in China. If the eight new species published in recent years were accounted, there are thirty-one Mains species in China. About the exact number of the species in genus Mains, however, is still contentious even among the taxonomists of pomology today. The distribution of Malus species covers all the twenty-nine Provinces, Municipalities or Autonomous Regions of China. Among them the most widely distributed two species are M. hupehensis (Pamp.) Rehd. and M. sieboldii ( Reg. ) Rend., which covers 17 and 15 Provinces, Municipalities or Autonomous Regions respectively. The most densely populated areas by species are Sichuan, Yunnan, and Guizhou-and-Shaanxi Provinces of Southwestern parts of China, which has 24, 17, and 15 species respectively. The altitude variation of the distribution of the different Malus species in China reaches nearly 4000 meter , they grow on various soil types , even on desert, alkaline soil and rocks of steep cliffs.In the past several decades, various kinds of and systematic research work has been carried out on the apple genetic resources in China. As results, many progresses have been made with respect to the studies of the number of species, geographical distribution, morphology, classification, cytology, zymology, reproductive biology and resistance characters to the environmental stresses. There are, however, many problems still need to be solved in the future work. Firstly, on the subject earches, we have done "too much" work on basic researches and obviously neglected application studies. We failed to pay more attentions on the research of the rare gene materials in genus Malus, such as M. xiaojinensis. Secondly, our laboratory equipments are old and research techniques backward. Traditional field conservation method for apple genetic resources was suffered from the serious problem of lacking fund. The existing research and maintenance system for apple genetic resource could no longer work properly if no improvements were made. The lose of the currently conserved plants increased daily because of the pests and environmental influences. Many precious gene materials now maintained are in danger of being lost again and for ever. The research using the modern molecular technology in studies of genetic conservation, identification and utilization of the useful apple genes was nearly a blank. Thirdly, the genetic diversity of species is a very important subject of modern genetic resources research. Because it was a basis for the study of evolution, classification, conservation and utilizations of apple genetic resources. In this field of study we also need to start with.M. Xiaojinensis Cheng et Jiang, distributed in the upstream of Minjiang river and middle to upper reaches of Daduhe river and the area is called Mingjiang-Daduhe strand in eco-gepgraphy, is the first new species named by Chinese in the taxonomy of Mains Miller in the world. M. Xiaojinensis is also an endemic species in the highland area of Western Sichuan Province. All the existing experimental results available showed that M. Xiacjinensis was not only tolerance to various environmental stresses, such as soil salt, draught, heat, cold etc; it also showed stronger resistance to different latent viruses of apple than other apple rootstocks. In addition, the high degree of apomictic character of M Xiaojinensis, its good grafting affinity to major apple cultivars, its semi-dwarfing , early fruiting, and fruit quality improving effects on the grafted trees, make M Xiaojinensis better than M7 in terms of the overall characteristics as apple rootstock. But there are many questions concerning M. xiaojinensis, such as the molecular basis of its environmental resistance characters, the genetic...