QTL Analysis Of Fruit And Seed Related Traits In Melon

Melon(Cucumis melo L.)is a Cucurbitaceae crop and its fruit and seed related traits have been the focus of breeding workers.In recent years,more and more people are committed to improving fruit yield and improving fruit quality.The seed traits could determine the initial germination and growth ability of melons,which is an integral part of ensuring that melon is well grown.In order to study the inheritance of melon fruit and seed traits and QTL analysis.The F2: 3 population was constructed with the muskmelon strain ms-5 and the Chinese melon cultivar HM-1with significant agronomic traits.The polymorphism CAPS molecular markers were developed based on high-throughput re-sequencing data to construct the genetic linkage map and QTL analysis.Genetic analysis and QTL mapping of melon fruit,seed and other related traits were carried out with field phenotypic data,The candidate gene prediction were also performed with the related QTL and the main results are as follows:The segregation of fruit weight,fruit length,fruit width,fruit shape index and fruit thickness were all normal distributed in the F2:3 population,indicating that these traits were all quantitative traits.Fruit length,fruit width and fruit shape index were significant correlated.The seed weight,length and width of the seed-related traits of melon were also significantly correlated with each other,and the field traits were in line with the positive traits.In this study,CAPS molecular markers were developed by high-throughput sequencing,and 523 pairs of primers were evenly designed on the 12 chromosomes of melon.170 polymorphism markers were selected with the polymorphism ratio of 32.5%.A genetic linkage map of melon was constructed with 159 CAPS markers and 12 linkage groups(corresponding to12 chromosomes of melon),covering the genome length of 1 771.53 c M with the average genetic distance of 11.35 cM.Among them,Chromosome 9 contained the most markers of 29.The distribution of the markers on the genetic linkage map is consistent with the physical position of the CAPS locus.A total of 18 QTLs were detected with fruit related traits,and the LOD value ranged from2.82 to 18.78,which could explain the phenotypic variation rate of 2.68%-79.40%.There were4 QTLs associated with fruit weight located on chromosome 2,6 and 8,respectively.There was1 QTL in fruit length,located on chromosome 2 and the fruit width was located at chromosome6,the QTLs of fruit shape index were located on chromosome 2,6,7.3 QTLs related with flesh thickness,on Chromosome 2,7.A total of 7 QTLs related to seed related traits were detected,and the LOD value ranged from 3.60 to 8.66,which could explain the phenotypic variation of8.07%-19.53%.There were two QTL loci related to the 100 seed weight,and all of them were located on chromosome 6.There were four QTLs related to fruit length,located on chromosome5,9,11.And the fruit width related QTL located on chromosome 11.The QTL locus FS6.1 was located between B0610 and E0623.The genetic distance between the two markers was 0.27 cM with the LOD value of 6.14,and the phenotypic variation was explained 5.27%.The QTLs were obtained by gene sequence alignment.Located in the melon genome scaffold00027,the gene annotation results found that the region has 26 candidate genes.