Using Of Pyramid Breeding System By Rolling Convergent Backcross Combined With Genetic Markers In Wheat Breeding

Wheat is a kind of very important crop in our country. It is of great significant to develop polygene pyramid breeding technique and its theory. In this research, we put forward and validate a pyramid breeding system of rolling convergent backcrosss combining with genetic markers. The results are as follows:l.We have compared the compositive characters of lines carrying different targetcharacters by rolling convergent backcross with the donor parents and the recurrent parents, the results show that rolling convergent backcross can eliminate the bad properties of the donor parents effectively and reserve most of the characters of the recurrent parents, the compositive characters can reach or even surpass the recurrent parents.2.In this research, three waxy genes and the resistance gene Pm21 which is anti-wheat powdery mildew and gene Nib-8 which is anti-wheat yellow mosaic virus were pyramided in wheat by rolling convergent backcross combining with genetic markers selection. Finally, we successfully obtained 6 plants carrying gene Pm21, gene Nib-8 and wx genes simultaneously, 26 plants carrying gene Nib-8 and wx genes and 13 plants carrying gene Pm21 and wx genes from BC2F2. According to the results of resistance identification and molecular markers detection, some waxy plants (about 47.5 percent) obtained immunity from wheat powdery mildew disease and highly resisted WYMV disease were filtered from F3 segregation population. It showed that we could pyramid many target characters under agricultural parent background by combining with phenotype identification, special physiological and biochemical representation along with molecular and biochemical marker assistant selection.3. Immature embryo culture combined with adding generation in greenhouse and breeding in summer in other regions can realize growing wheat three generations in a year, this method can faster the generation course, and it tends to resolve the problem ofexcessive cycle of wheat breeding.4. We optimized the process of improved 1D-SDS-PAGE electrophoresis of Waxy protein subunits. As a result, we could separate three Waxy protein bands clearly. We also did some researches on the separation law of three Waxy loci and gained all 7 Waxy protein subunits null type, three types of them were never found in the nature. The results of statistics indicated that three recessive genes controlled wheat waxy trait. We have validated some molecular markers of Wax gene. Wx-Al codominance marker was used to detect the heterotic genotype of Wx-Al loci. Wx-Bl STS marker was used to detect mutation of Wx-Bl loci specifically. In addition, we found an abnormally phenomenon when using Wx-Dl PCR marker to detect herterozygote DNA. This molecular marker of Wx gene could be used to filtrate wheat haploid of null Waxy protein subunits, and finally we gained 3 plants whose genotype is abd(waxy), 6 plants whose genotype is ABd, 3 plants whose genotype is Abd, and 7 plants whose genotype is aBd.