High-density Molecular Genetic MAP Construction And QTL Mapping For Some Fruit Traits In Hawthorn

Hawthorn(Crataegus spp.)is an important fruit tree resource of Hawthorn of Rosaceae,but its long growth cycle,complex genetic composition and self-incompatibility limit the development of new varieties of Hawthorn.In this study,a hybrid population was established in which the hawthorn varieties 'Shandong Damianqiu'(mother)and 'Xinbin soft seed'(father)were significantly different in fruit size and fruit firmness,and 130 hybrid F1 generations were selected as the mapping population.The SNP markers developed by RAD sequencing technology were used to construct high-density molecular genetic maps of hawthorn.The phenotypic traits of single fruit weight,longitudinal diameter,transverse diameter,peeling hardness,peel fragility and average pulp hardness were investigated.The interval mapping in the Joinmap6.0 software was used to study the QTL mapping of the 6 traits of the group fruits.The main findings are as follows:1.The two pairs of primer combinations 'CH05e06' and 'CH03g06' were used to identify the true and false hybrids of the hybrid seedlings from 128 pairs of primer combinations.The results showed that the 130 hybrid progeny plants used in this study were all true hybrids..2.6384 high quality SNP marker sites were obtained by screening.JoinMap was used to map the genetic map of the parents and the genetic map of the parents.The three maps contained 17 linkage groups.There are 2656 SNP markers in the genetic map of the female 'Shandong Damianqiu',covering a total map distance of 2681.65 cM,the average genetic distance between the loci is 1.34 cM,and the average length of the linkage group is 158.21 cM.The average number of markers is 1564;the genetic map of the father's 'Xinbin soft seed' has a total of 4,085 SNP markers,covering a total map distance of 2,558.41 c M,the average genetic distance between the loci is 0.64 cM,and the average length of the linkage group.For 150.49 cM,the average number of markers per linkage group was 240.29;there were 6384 SNP markers in the integration map,the total coverage was 2470.02 cM,the average genetic distance between the sites was 0.41 cM,and the average length of linkage groups.For 145.30 c M,the average number of markers per linkage group is 375.533.Two QTL loci related to single fruit were detected in the integrated map,and the phenotypic variation rate was 19% and 21.8%;the QTL loci related to the longitudinal diameter were 2,an interpretable table.The phenotypic variation rate was 18.1% and 24.3%;the QTL locus associated with the transverse diameter was 1 and the interpretable phenotypic variation rate was 21.4%;the QTL locus related to the puncture hardness was 6 and the phenotypic variation was explained.The rate is between 17.7% and 25.2%;there are 5 QTL loci associated with peel fragility,and the interpretable phenotypic variation rate is between 18.1% and 32.2%;the QTL locus associated with the average hardness of the pulp is 5 The explained phenotypic variation rate is between 18.1% and 19.9%;The genetic map constructed in this study is the genetic map with the largest number of molecular markers reported in the genus Hawthorn,which not only lays a foundation for the fine mapping of HTL important hawthorn in the future,but also promotes the molecular breeding of Hawthorn.effect.