Genetic Study And Molecular Marker On Immature Fruit Color Of Cucumber

Hybrid combinations of cucumber were made with two inbred lines with different immature fruit skin color that use the inbred lines with milky white as the female parent and the inbred lines with dark green as the male parent. The C and L values of immature fruit skin color were measured by color difference meter after visually classified.The generations of F1, F2, backcrosses B1and B2and their parents P1and P2were used to explore the inheritance of immature fruit skin color traits with the method of conjoint analysis. Meanwhile, gene primary mapping was carried out on green gene of immature fruit skin color in cucumber. The central results of this study were following:1. The major gene and poly gene (E-0model) inheritance of immature fruit skin color in cucumber accorded with the additive-dominance-epitasis pattern. The L value and C value of major gene heritability in F2are93.61%and80.86%respectively. The major gene heritability in F2is higher while the polygene heritability and environmental effect are lower, so we suggest that the fruit skin color breeding of cucumber should be selected in the early generation.2. Fruit color was classed by ocular measurement, then whether the actual value accorded with the theoretical value was examined by χ2test. The results showed that the immature fruit skin color was green in the generation of F1. The colors were separated in F2populations, both the plants with green immature fruit skin color and with white color appeared in all the F2populations with a3:1segregation ratio, and the ratio in B2(F1×P2) was1:1, and the immature fruit skin colors of B1(F1×P1) populations were all of green. According to this, we can deduce that the immature fruit skin color of green was dominant in white and they were controlled by one gene.3. The F2segregating populations of the hybrid combination (H4×Q1) were used for primary mapping. Two gene pools of green and white were made from F2populations by BSA method. One pair of SSR primer SSR15312selected from995pairs of primers distributed in genome-wide of cucumber. The primer SSR15312showed stable polymorphism between the two parents and gene pools and it was chained with the target gene. The gene controlling green trait was in the3th chromosome according to the chromosomal locations of the SSR markers. 4. Though the verification of primer SSR15312with the F2(144), B1and B2populations, it indicate that the primer SSR15312was co segregation with the gene controlling green trait. The primer SSR15312implied two specific bands in the parents that the lengths were207bp and187bp respectively, and the difference was10" TA" duplications.5. Using the results of gene prediction the result of the comments and provided by the cucumber genome program (GUGI), the preliminary positioning area of the target gene sequence were anglicized. Through the comprehensive analysis of the BLAST results of NCBI and soft berry gene structure prediction results, preliminarily concluded that the green gene of immature fruit skin color may associated with the chloroplasts related genes.