The Genetic Behaviour Of Thinopyrum Intermedium Chromosome 2Ai-2 In Wheat Backgrounds And The Inducation, Identification Of Its Translocation Lines

The disease of wheat which were caused by barley yellow dwarf virus (BYDV) is one of the most serious diseases in china. It did a lot of harm to the northwest and northern wheat area. Recent years, the disease is spreading to other region of china. Breeding and use of resistant cultivars is the most economical and effective approach to control this disease. The gene with high resistances to the GPV and GAV strains of barley yellow dwarf virus spreading widely in our country was locaed on Thinopyrum intermedium Chromosome 2Ai-2. In this paper, different wheat–alien disomic (or ditelosomic) substitution lines were crossed with common wheat variety Chinese Spring to generate the BC1 and F2 populations, and the genetic behaviour of Thinopyrum intermedium Chromosome 2Ai-2 in different wheat chromosome substitution backgrounds of group 2 was studied. And we also induced hybrids by two methods of tissue culture and CSph1b mutants. The populations were detected using EST-PCR markers specific to 2Ai-2 chromosome and genomic in situ hybridization (GISH) in order to study the transmission ratio, types of structure variation as well as pairing behaviour affected by gene Ph1. Main results are as the following.1. Studied to the genetic behaviour of Thinopyrum intermedium chromosome 2Ai-2 in different wheat chromosome substitution backgrounds of group 2, we found that the effect of different substitution background on the transfer of the 2Ai-2 chromosome was different.. The alien chromosome or fragment preferentially transmitted in 2Ai-2 (2B) substitution lines . On the contrary, the transmission ratio of the alien chromosome or fragment was low in 2D-subsititution background. So 2Ai-2 (2B) substitution background was propitious to the transfer of the 2Ai-2 chromosome. In addition, the alien chromosome was unstable when transmitting from hybrid to subsequent generations, it sometimes occurred structure variation. In most crosses, chromosome variances occurred near centromere. Compared with the short arm, the long arm of the alien chromosome was lost more often in the next generations. Structure variation of telosome 2Ai-2S was also observed in the offsprings with 2AS-substitution background. GISH results confirmed that the EST-PCR markers can be used effectively in tracing the alien chromosome in wheat background.2. By virtue of EST-PCR markers specific to 2Ai-2 chromosome and the technique of GISH, we selected two 2Ai-2S homozygous translocation lines, one 2Ai-2L heterozygous translocation line, three ditelosomic lines and five monotelosomic lines from SC3 regenerated by immature embryo culture. Results shows that variation induced by mature embryo culture mainly occurred on the region of centromere.3. The pairing behaviour of Thinopyrum intermedium chromosome 2Ai-2 and wheat chromosomes controlled by gene Ph1 was studied. We found that the pairing frequency differs little in different substitution backgrounds (2B substitution background or 2D substitution background). In 2Ai-2 (2B) substitution background, the pairing frequency of chromosome 2Ai-2 is about 5.2% in all the 193 cells. While in all the 360 cells in 2Ai-2 (2D) substitution background, the frequency is about 3.1%. And the pairing between chromosome 2Ai-2 and wheat chromosomes were more tight in 2D substitution background. The chromosome 2Ai-2 usually stay in the form of univalent, and there is about one multivalent which refers to wheat chromosomes in a cell on average.