Identification Of Wheat Germplasm Line Shannong495 And SSR Molecular Mapping Of Its Rht Gene

The so-called"green revolution"took place in the 1960s because of the generalization of the dwarfing wheat and rice. So dwarf breeding has become a major path for high yield breeding. 25 dwarfing genes which have been discovered are not used sufficiently, besides breeding only center at few of them. Because of these it is important for wheat breeding that keeping on creating, discovering new dwarfing sources and enriching their diversity. With the development of molecular marker, the foundation of molecular mapping of dwarfing genes has been a credible and effective method in selection of the dwarfing character on genetic level. Agronomic traits investigation, cytological characteristic identification and molecular technique have been carried out in Shannong495 which was created from BC2F4 crossing and backcrossing between Jinan17 and Am6(Aegilops tauschii(DD)-Triticam carthlicum(AABB)). The location of the dwarfing gene using molecular markers is studied simultaneously. The results are showed as follows:1,The characters of Shannong495 was identified integrativly using the morphology and cytology. The results indicate that the dwarfing germplasm line Shannong495 with good cytological stability have good field characters and no premature senility. It is very valuable in the area of plant breeding and genetic improvement.2,The height of the plants of F₁ which were created by crossing between the dwarfing germplasm line Shannong495 and the high germplasm line Shannong289 is close to the high material. And then the genetic character of dwarfing gene in Shannong495 was analyzed in F₂ population and BC₁ population. The results are showed that the proportion of the dwarf and high individuals in the F₂ segregating population was 1:3, the proportion of the dwarf and high individuals in the BC1 population was 1:1. The dwarf gene shows GA insensitivity through GA reaction identification. In a word the dwarfing character is controlled by a major recessive gene which is insensitive to GA.3,1589 genomic SSR and EST-SSR markers were screened for polymorphism in the Preferred Small Group (PSG) in 162 individuals of BC₁ population and 304 individuals F₂ population. After that two genomic SSR markers (Gwm113₁₉₆ and Wmc511₁₉₁) and one EST-SSR marker (Dupw23₂₁₀) on 4BS were identified polymorphic. These polymorphic markers were used to screen in BC₁ and F₂ segregation population, coming to a conclusion that all the three polymorphic markers were linked to the dwarf gene. The genetic distance between Rht gene and microsatellite markers, Gwm113₁₉₆, Wmc511₁₉₁and Dupw23₂₁₀ was 3.9 cM,5.2 cM,21.6 cM using BC₁ population respectively and 4.1 cM,5.0 cM,19.8 cM using F₂ population respectively. These three markers can be used in molecular marker-assisted selection.