Purification And Application Of High Resistant Polymerization Melon

Gummy stem blight(GSB)is caused by Didymella bryoniae and is a serious fungal disease of melon(Cucumis melo L.).The resistance of melon varieties carrying a single resistance gene is not enough to the disease because of the change of cultivation environment.Therefore,this study aims to develop a molecular marker-assisted selection system and provide an important intermediate material for melon disease-resistance breeding.Three different gradient spores vaccination identification(5×105 spores/mL,5×107 spores/mL and 5×109 spores/mL)was employed to distinguish the resistance of F1 plant of different polymerization resistant sources.The gene combinations of 145-471 and 145-398 with their resistance significantly improved were screened by inoculation identification results of spring and autumn.Single resistant sources PI140471,PI482398 and PI420145 were used as the donor parents with the gummy stem blight resistance genes Gsb-1 Gsb-4 and Gsb-6,respectively.Commercial melon cultivar ’Baipicui’ was used as the receipt parent to cross and backcross with the donor parents.Marker assisted selection(MAS)and gradient spores vaccination identification were used in each backcross and self-cross progeny.The results of disease resistance evaluation indicated that the molecular markers developed in the study were efficient in selecting three resistance genes by MAS.The molecular marker-assisted selection system developed in this study was efficient for pyramiding multiple resistant genes.The resistance improved materials of Baipicui would be used in breeding and further resistance gene pyramiding.1.Development of Multiplex PCR Detection Method for genes resistance to gummy stem blight in melon(Cucumis melo L.)The purpose of this study was to development a multiple SSR-PCR system for genes resistance to gummy stem blight in melon.By optimized the concentration of primers and the unit of Taq DNA,based on the different fragment size of SSR amplification products.The multiplex PCR methods detecting Gsb-1 gene(189bp)and Gsb-4 gene(121bp)were developed.The polymorphism produced by multiple PCR reaction was identical with that from single PCR,but it showed a higher efficiency than the single PCR.The establishment of multiple PCR system for genes resistance to gummy stem blight in melon would greatly accelerate the speed for identifying the variety purity and authenticity of pyramiding resistance genes,and further promote the development of other areas in melon molecular biology.2.Expression analysis of the defense gene PAL in melon(Cucumis melo L.)With the susceptible variety ’Baipicui’,single-sources PI140471(Gsb-1),PI420145(Gsb-6)and pyramided genes materials 145-471(Gsb-1 and Gsb-6)as the tested materials,we investigated the different resistant performance by gradient spores vaccination identification and the different expression of PAL by RT-PCR method The results showed that pyramiding resistance genes could enhance the resistance to GSB.The PAL expression in different tissues were first increased and then reduced to stable,but the change speed and range were different.The pyramided hybrid 145-471 can be used for pyramiding breeding of melon.The defense gene PAL played an important role in the melon resistance to GSB processes,its higher and earlier expression in the pyramided genes materials can provide higher resistance.3.Pyramiding disease resistance genes by marker-assisted selection in melon(Cucumis melo L.)and ’Baipicui’ breed improvementSingle resistance source PI140471 PI482398 and PI420145 were used as the donor parents with the gummy stem blight resistance genes Gsb-1 Gsb-4 and Gsb-6,respectively.Commercial melon cultivar ’Baipicui’ was used as the receipt parent to cross and backcross with the donor parents.Marker assisted selection(MAS)and gradient spores vaccination identification were used in each backcross and self-cross progeny.At F7 generation,the pyramiding lines with homozygosity at both gene loci were obtained.The polymerization individuals showed higher resistance than single resistance source PI140471 PI482398 and PI420145.The individuals were resistant to melon gummy stem blight,which was accordant to the expected result of molecular detection.Developed a molecular marker-assisted selection system and provided an important intermediate material for melon disease-resistance breeding.