Studies On Inheritance And Molecular Marker Linked To Monoecious Gene Of Melon (Cucumis Melo L.)

In order to obtain different generations of Cucumis melo L., the hybrids (F1) were made by crossing, between monoecious Fi-155(P1), S160-1(P2) and andromono- ecious materials Fi-1(P3), Fi-2(P4), Fi-3(P5), Fh-232-3 (P6) and F2,BC1 and BC4S6 were generated by selfing and backcrossing respectively. They were used to analysis the segregation patterns of flower sex types in different generations. F2 population from P2 and P6 were studied by RAPD technique.Segregation patterns of flower sex types were investigated in different generations. All F1 generations, the hybrids between monoecious and andro- monoecious materials, were monoecious plants, which indicated that monoeciousness of parents P1,P2 was under the control of a dominant gene and inherited steadily. Using chi-square testing, the result showed that the segregation patterns of flower sex types in F2,BC1 and BC4S6 generations conformed to the segregation ratio controlled by a single dominant gene.RAPD technique was carried on in F2 generation from the hybrid between P2 and P6. Modified CTAB was used to extract genomic DNA from C. melo. Single factor selection was used to optimize the RAPD reaction system in this study. The optimal value obtained from the last screening was used to screen the next factor as a fixing value until the optimal RAPD-PCR reaction system was built. The results showed that the optimal PCR system for RAPD analysis in melon was as follows: the genomic DNA concentration was 3.75ng/μL;dNTP concentration was 0.25mmol/L; primer concentration was 0.50μmol/L and Taq DNA polymerase concentration was 1U/rec in 20μL reaction system. The optimal PCR system layed a good foundation on the research of marker-assisted selection for monoecious of flower sex type in C. melo.Using this optimal RAPD reaction system, 200 primers were selected to screen RAPD markers linked to monoecious gene in F2 (P2×P6) through using bulked segregant analysis (BSA) strategy. 5 specific polymorphism primers were screened, one of which, only T16571 primer (550bp) was found a characteristic band in most of F2 monoecious individuals, which was named T16571550. This primer marker can be used in marker-assisted selection for monoecious flower type in melon.