Genetic Evaluation Of Main Characters And Study Of Molecular Marker Technique In Peach

Peach (Prunus persica (L.) Batsch) is native to china where are rich germplasm. Cross breeding was still main methods for breeding new peach cultivars. Genetic evaluation of main characters can provide basic genetic theory for selecting parents and improving efficiency of peach breeding. Molecular marker as a newly appeared technique can enrich the results of normal method, and supply molecular basics for breeding program, genetic relationship and evolvement of peach.In this paper, inheritance of maim characters as pubscent/glabrous fruit surface, flesh color, pollen fertility, fruit shape, fruit flavor and fruit repining time of peach were systematically analyzed using controlled crosses. Genotypes of breeding materials of peach were also identified. Genetic relationship of peach species was analyzed by SSR and evolvement relationship among species was deduced. Molecular markers linked to pubescent/glabrous fruit surface, white/yellow fruit flesh color and fertile/sterile pollen were found using bulked segregation analysis. The details were as follows:1. Genetic evaluation of main characters of P. persica (L.) BatschBased on the practice of peach breeding, this paper systematically analyzed the inheritance of pubscent/glabrous fruit surface, flesh color, pollen fertility, fruit shape, fruit flavor and fruit maturing time of the parents, F1 and F2 hybrids. The results were as follows:Pubescent/glabrous, flesh color and pollen fertility were proved to be each controlled by a pair of alleles, with pubescent peach completely dominant to glabrous nectarine, white flesh to yellow flesh and pollen fertility to pollen sterility. The three alleles appeared to follow the rule of independent assortment, without linkage of interaction among them.Fruit shape was controlled by one pair of alleles. Flat shape was dominant to non-flat shape. Non-flat shape such as round, near round, ovate and ellipse were appeared in hybrids. Shapes of fruit top were diverse, such as round, plainness, concave, mammilla, sharp and so on, most of which were similar to that of parents. The height, width, depth and height/width of flat hybrids were similar to their flat parents, no intermediate shapes occurred.Fruit flavors such as sweet, sweet with sour, sour with sweet and sour were all appeared in hybrids. Rate of nectarine seedlings with sweet flavor was high when varieties with sweet flavor as parents. More hybrids with sweet flavor were appeared in cross with flat peach as parents, especially flat offspring. The result indicated that genetic potential of fruit flavor of flat peach was strong. No linkage relationship were found between sweet flavor and flat shape, according to this result we presumed that genes control the tow traits were near but with genetic distance in genome, so frequency of recombination between the two gene were low, this cause flat peach to be sweet.Fruit maturing period classified as early, mid and late were controlled by respective major genes and modifying factors. Ratios of early, mid and late individuals from the combinations of MidxEarly, MidxMid, Mid*Late, Late*Mid, Late*Late, LatexEarly were 4:3:1, 0:3:1, 0:1:1, 0:1:1 and 1:0:1 respectively. The heritability of fruit ripening dates was 0.80, and there exited a significant transgressive inheritance. To obtain mid ripening individuals, mid season cultivars must be used as one of the parents, and crosses between late and early season cultivars were not suitable. Late ripening individuals may be obtain from any crosses, but the percentage of late ripening seeding will be the highest in crosses between late season cultivars.2. Genotype analysis and utilization of new created germplasm of P. persica (L.) BatschGenotype of qualitative traits such as pollen fertility, nectarine, fruit shape, flesh color, flesh firmness, freestone or clingstone and so on used as breeding materials were valuated on the basis of the previous research of peach breeding. Cultivars with genotype as psps> Psps, PsPs. Hh, Sasa, Yy. YyMmff. yymmff, yyM_fl\ yyMmff. yyM_F_, yyMMFf, yyMmFf were identi...