The Natural Selection Effect On Resistance To SCN And Major Agronomic Characters Of Soybean

Good adaptability genotype is essential to obtain super-high yield by selection and breeding. So it is vital to study the interaction between genotype and phenotype for improving adaptability to ecological environment. And it becomes more important to reveal natural selection effect on major traits under different ecological environment for it's research on genetics and utilization in breeding. The natural selection effect on resistance to SCN and major agronomic characters of soybean was distinguished by comparative the difference of its phenotype and SSR marker of resistance gene which was derived from the same cross. The results were as follow:1 The resistance to SCN was identified for comparative inheritance and variance between populations "NJ(RN)P7"and "JN(RN)P7". The results show that, 3 recessive genes conditioned the inheritance of resistance to race 1 in these two populations, but significance was detected for the means of female index on two populations. There are obviously natural selection effects on resistance to SCN. One of major reasons is that there are really different between two populations and it is confirmed by analyzing variation of phenotype.2 The inheritance and variation of resistance was comparatived by SSR marker with BSA method. The DNA bulks of resistant and susceptibe were constructed with 5 and 10 families, respectively. For two populations, some primers were found polymorphism between resistant and susceptible DNA Bulks with relation to the resistance of race 1,2,3 and 5, and two markers Satt163,Satt309 were also found polymorphism which were reported with relation to rgh1 by some researchers. While a new maker Satt333 was found which were never reported with relation to resistance of SCN.3 The natural selection effect on part of qualitative traits was distinguished by comparative the difference of its phenotype which was derived from the same cross. When these four RILs populations were planted in Jinan, different significances were detected for seed shape, seed color, hilum color, and color of hairs on soybean in the two populations which derived from cross "Peking×7605"; so did the seed shape in the other two populations derive from cross "RN-9×7605". And genetical diversity of the four populations was evaluated for these qualitative traits by Shannon-weaver index and Simpson index, the results show that diversity is various through hybrid combination and traits.4 The natural selection effect on soybean major quantitative traits was distinguished under different environments by comparative the difference of its phenotype which was derived from the same cross. When these four RILs populations were planted respectively in Nanjing and Jinan, different significances were detected for plant height and branches in the two populations which derived from cross "Peking×7605"; so did the branches, availability pods,seeds per plant, 100 seeds weight in the other two populations derive from cross "RN-9×7605". There are obviously natural selection effects on described traits as hereinbefore. It can be explained that there are really differences between two populations deriving from the same cross and it is confirmed by analyzing variation of phenotype.5 NJ(RN)P7and JN(RN)P7 were used to study correlation in Agronomic traits and resistance to SCN. The results indicated that: For NJ(RN)P7 population, the correlation between resistance and seed color, nodes per plant and 100 seeds weight were significant, while the correlation between resistance and sterile pods, days to mature were significantly negative. And the correlation between resistance and seed shape, seed color, hilum color and color of hairs on soybean were significant for JN(RN)P7 population.