Toward Practical And Theoretical Exploring On Genetic Improvement To Hua Yu 4 By MAS

QPM which is very important in whole industry structure have good edible and feeding effect,thertorcimproving our nation's QPM breeding and dveloperncnting our nation's QPM yield has practice and stratagic significance in adjusting our nation's agriculature structure.In our research, we have introgressed o2 gene into parent lines of HuaYu 4:S7913 and HZ85 through three continuous backcrossing by MAS.On early stage of each backcross generation we carry out foreground selection.Later,we implement background selection and PS in selected individuals ,which one get across all these selections was backcossed and its offsprings was put in next selecion cycle.In SCBC1F1 population,using 148 pairs of SSR primers to do background selection on 32 individuals those linkage drag at one flank were controled in 7.0cM,the genetic background resemblace of these individuals to the recurrent parent's is average to 85.1%;Thereinto ,one individual whose linkage drag at one flank was controled in 0.9cM ,its genetic background resemblance to the recurrent parent is 88.9%.In HCBC1F1 population,using 146 pairs of SSR primers to do background selection on 19 individuals those linkage drag at one flank were controled in 7.0cM,the genetic background resemblance of these individuals to the recurrent parent's is average to 84.2%;Thereinto ,one individual whose linkage drag at one flank was controled in 2.8cM ,its genetic background resemblance to the recurrent parent's is 88.0%.Five SSR markers which flank with o2 gene were used to analyze the linkage drag of SCBC1F1 and HCBC1F1 population.The results were compared with the results of Ribaut(2002) who made a computer simulation of MAS.We find that in MAS programme ,three parameters:Ni,Nj and linkage drag need to be considered simultaneitly to estimate the size of BC1 population.We employed phenotypic selection in SCBC1F1 and HCBC1F1 population.We analyzed experimental data by Bayesian method.Later,we compared the result with MAS result.In autum 2003,Two selected individuals one in SCBC2F1 and the other in HCBC2F1 population were self-crossed.In spring 2004,we do foreground selection in SCBC2F2 and HCBC2F2 population,the individuals which genotype was o2o2 was selected and self-crossed,Later,we analyzed their lysine content of kernel.Three selected individuals in SCBC2F2 population with their average lysine content of kernelto 0.41% and another three selected individuals in SCBC2F2 population with their average lysine content of kernel to 0.40%.The result match the requirement of QPM breeding.In our research,we also discussed what is Ihe best strategy and stage of selection.We agreed that, first,we need to collect non-rccurrcnt parent lines as much as possible;second,the optimized selection stage to get rid of linkage drag and to employ background selection is BC| generation;third,it is no good to employ phenotyic selection in BC1 gcneration;last,in background selection it is good to adopt the strategy of step by step".