Localization Of Sugar Gene QTL And Disease Resistance Pyramiding Breeding In Melon

This study aimed at the needs of melon germplasm for sugar content and disease resistance breeding.The F₂ population was constructed by using high-sugar inbred line X25R,M157R and low-sugar inbred line JSR as parents.In order to study the genetic regularity and gene location of sugar control genes in melon,the F₂ population were constructed from melon cultivars MR-1 resistant to bacterial fruit blotch disease and Jiashi melon susceptible to bacterial fruit blotch disease.The inheritance and gene localization of bacterial fruit blotch disease resistance were investigated in MR-1.The agronomic traits QTLs localization were performed in the cross from Annong 2 and Hami melon K413 recombinant inbred lines.The inbred line X25,M157R,JSR and the Chromosome Segment Substitution Lines MH were regarded as parents to breed the melon cultivar with bacterial fruit blotch disease resistance,powdery mildew resistance by MAS.This study provides a theoretical basis for the subsequent use of resistant and high sugar varieties for variety improvement and molecular marker-assisted selection for breeding.The main results are as follows:?1?F₂ segregation population was used to locate the genes of sugar content.There were significant differences between phenotypes and genotypes detected on LGIV,LGX and LGXI.These loci of ECM134?LG IV?,MU3349?LGXI?and CMAGN45?LGXI?were identified in inbred line X25R×JSR F₂ population,and MU5035?LGX?and chr10-0380?LGX?loci were identified in inbred line M157R×JSR F₂ population.?2?Two powdery mildew resistance genes were pyramided simultaneously by MAS breeding.Six powdery mildew resistance locus heterozygous families,one powdery mildew resistance locus homozygous family and one powdery mildew resistance locus heterozygous family were obtained.?3?F₂ population from the cross between MR-1 and Jiashigua were used to locate the genes of bacterial fruit blotch disease resistance.The bfb-QTL12.1 was located between CMMS35-4 and DE1851.The physical distance between the two markers was about 3.4 Mbp and the genetic distance was 9.1 cM.?4?A heterozygous family with resistance loci of bacterial fruit blotch disease was obtained by using the chromosome substitution lines of MR-1 and Queen.?5?Using RIL₈ from the cross between Annong 2 and Hami melon K413,11agronomic traits were primarily located in the genetic map established in previous research.?6?Using backcross population No.100 containing powdery mildew resistance gene,powdery mildew resistance breeding was carried out,and a heterozygous family with powdery mildew resistance loci and good agronomic traits such as sugar content was obtained.