| Wheat (Triticum. aestivum L.) is the one of the most important crops of the world. Wheat is also a young heterologous hexaploid plant species, which includes 3 genome groups originated from different sources. Because of it, the evolution of wheat genome and the ability of utilize alien germplasm shows a great advantage. This paper used the method of distant hybridization, introduced rye genes into wheat, and indicated that alien gene resources could improve the agricultural characters of wheat, and created new agricultural characters which are not been occurred. The base of these works is the research of diversity of alien germplasm. The works of this paper include:1.Genetic diversity of 23 accessions of Secale L., representing 5 species and 13 subspecies, was evaluated using inter simple sequence repeat(ISSR) markers. 12 ISSR markers were screened from 100 UBC-ISSR markers and used for the PCR amplification of genomic DNA,which could produce clear and polymorphic bands.A total of 850 bands were amplified from 12 primers, of which 804 bands(about 94.5%)were polymorphic, and 14 to 121 polymorphic bands could be amplified from each primer,with an average of 70.8 bands.The variation range of mean genetic similarity (GS) value based on ISSR markers among 23 accessions of Secale L . was 0.4810-0.8734.Cluster analysis showed all materials could be classified into 3 groups. The repeat sequence's increase accompanied with the evolution process of Secale L. the repeat sequences were least in S.africarnurn,and S.sylvestre, but most in Secale L. ssp. cereal. The result showed the polymorphism not only exists in different species, sub-species, but also in same rye cultivars.These results suggested that ISSR markers could be used as an effective molecular technique for the diversity and systematizes study of Secale.It is also suggest that production of genetic diversity by means of introducing the genetic variations of Secale L. into wheat is an advantaged method in wheat breeding.2. The 1BL.1RS wheat-rye translocation from Petkus rye has contributed substantially to the world wheat production. However, following the breakdown of disease resistance genes in 1RS, its importance for wheat improvement became less. We have developed a new 1BL.1RS line, R14, by means of crossing rye inbred line L155 selected from Petkus rye to several wheat cultivars. One new gene each for stripe rust and powdery mildew resistance, located on 1RS of the line R14, are tentatively named YrCn17 and PmCn17. YrCn17 and PmCn17 confer resistance to Puccinia striiformis tritici pathotypes that are virulent on Yr9, and Blumeria graminis tritici pathotypes virulent on Pm8. These two new resistances, YrCn17 and PmCn17, are now available for wheat improvement programs. The present study indicates that rye cultivars may carry yet untapped variation as potential sources of resistance.3. For investigating genetic foundation of the stay-green trait, the wheat cultivar MY11 (wild type for stay-green) was used as a parent in cross with the wheat cultivar Chong-Nong17 (CN17). CN17 hosts a new 1RS.1BL translocation chromosome and has been released in 2003 in China. This wheat cultivar displayed high yield potential and an expected agronomic character of stay-green of leaves after anthesis. In the F6 families from this cross it is easy to distinguish the stay-green and wild type plants in the field. In the late filling stage of grains the color of leaves of stay-green plant would still keep green, while the leaves of the wild type exhibited yellow. Chromosome components of forty-three F6 families originated from the cross CN17×MY11 were analyzed by means of C-banding and A-PAGE techniques. Twenty-five families were proved to contain the 1RS.1BL translocation chromosome, in which seventeen families exhibited stay-green after anthesis in the field. On the other hand, no one of the other 18 families with a pair of 1B chromosomes exhibits the character of stay-green. The result indicated that the stay green trait is controlled by the genetic interaction between the genes on the new 1RS.1BL and on other wheat chromosomes. A significant correlation coefficient between existence of the 1RS.1BL chromosome and stay-green ( r = 0.6861, P<0.001) reveals that the 1RS.1BL translocation chromosome in the wheat cultivar CN17 should carry a gene(s), which is necessary for leaf stay-green after anthesis. Genetic diversity of 1RS and 1RS.1BL chromosomes and its application in wheat breeding was discussed.4. utilizing the new chromosome engineering technique, and according to the objective of high yield, high quality and high resistance, our research team has released 13 new wheat cultivars which planted widely recently in the West Southern of China. All of these cultivars and 4 new wheat lines were studied by the A-PAGE method,improved Geimsa C-banding and Genome in Situ Hybridization(GISH). The results showed 7 new cultivars (lines) in which, chuannong 10, 11, 12, 17, 18, 20 and R291 carried 1RS.1BL translocation.Moreover, because chuannong12,17,18 exhibits high resistance to the powdery mildew disease and stripe rust disease but the resisted patterns were different from Yr9 and Pm8.Therefore,we were sure that Chuannong12,17 and 18 were new 1RS.1BL translocation line.In addition, the quality and agronomic characters of all wheat cultivars and lines used in this study were detected. The relationship among the quality, agronomic characters and the structures of chromosome in these cultivars shows, the resistance to disease still is the most important selection pressures in wheat breeding programs, and it is the most important factors for varieties of structures of chromosome. The quality and the agronomic characters were just to be assistant factors for wheat breeding. This study indicate, for further application of 1RS.1BL translocation in wheat breeding, it is essential to widen its genetic variation, specially the variation in 1RS arm of this translocation. Since there exists a wide genetic diversity in rye germplasm worldwide, it is may be important to use this variation in future breeding program by developing new 1RS.1BL translocations. The diversity of quality and agronomic characters should be found along with the diversity of resistance to diseases. |
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