Research On Methodology Of Germplasm Development With Source Of Hybrids By Using Marker-assisted Selection

Germplasm development based on different kinds of hybrids has played an important role in maize breeding, especially in China. Because single-cross hybrids are over 95% in maize production, research on marker-assisted methodology of developing germplasm suited as female and male parents in breeding based on single-cross hybrids is of practical importance in promoting breeding efficiency and effectiveness. A popcorn hybrid, "JB1", was used as the initial entry in the present study. Genotypes of its female and male parent were obtained through genotyping of the hybrid’s pericarp and embryo by using genome-wide simple sequence repeat(SSR) markers. On the basis, marker-assisted selection(MAS) was performed in progenies of F2 and two subsequent generations using the polymorphic markers distributed evenly on the ten chromosomes. In the end, three groups were obtained, i.e. male-like, female-like and middle type. And in order to evaluate the combining ability and the breeding value of these selected progenies, hybrids were made in F4 among the progenies from the male-like and female-like group selected by marker-assisted selection while testcrosses were also made between three testers and materials which selected by marker-assisted selection and breeding experience in early generation. Plot yield and comprehensive evaluation of 2780 hybrids were then conducted in Shunyi of Beijing and Yuxian of Hebei. The main results were as follows:1、In F4 generation, the similarity to male parent and female parent of selected materials could be as high as 79.5% and 73.7%, respectively. Phenotypic analysis showed that the plot yield of hybrid combinations between the male-like group and the female-like group was higher than those within each of the two groups.2、In this study, the testcross from the male-like materials displayed strong heterosis and had a higher plot yield than those from the female-like materials and the materials selected by breeding experience, and there existed some hybrid combinations whose yield exceeded the control(the original hybrid, JB1).3、The study proposed a technical route of SSR marker-assisted germplasm development based on maize hybrids which could be useful in promoting use efficiency of maize hybrids.