Binmap Constructing And QTL Mapping Of Fruit Related Traits In Cucurbita Moschata Pumpkin

Pumpkin(Cucurbita moschata Duch.),belonging to Cucurbitaceae,is an important vegetable resource crop in the world.China is a large pumpkin producing country with an annual output of 8.18 million tons,accounting for 29.6% of the global output(FAO,2018).Chinese pumpkin(Cucurbita moschata Duch.)is the most economic cultivars of the three main cultivars in China.As the effective hypoglycemic foods,the ratio of sugar and inositol in pumpkin plays an important part.In this study,the Chinese pumpkin(Cucurbita moschata Duch.)inbred lines CMO-E and CMO-X were used as parents,and their 122 eighthgeneration RIL populations were used as research materials.A high-density genetic linkage map of Chinese pumpkin was constructed.Composite Interval Mapping(CIM)was used to map the QTL of starch content,sugar content and inositol contentof Chinese pumpkin fruit during the commercial stage.This study will lay the foundation for the further fine positioning of these trait control sites and for the molecular marker-assisted selection of Chinese pumpkin.The main results are as follows:1.Construction of genetic linkage map of Cucurbita moschata pumpkinIn this experiment,high-throughput sequencing was used to sequence the whole genome of the parents and offsprings,with the sequencing depth more than 7x.Those 320867 screened SNP loci were used as markers,and genotypes were distributed among the individual plants of the population according to these markers.HighMap software was used to construct a genetic linkage map of Chinese pumpkin.In this study,a genetic linkage map consisting of 2221 bin markers,with a total length of 2199.12 cM,covering 20 chromosomes of Chinese pumpkin was constructed.The genetic map constructed in this study is tightly labeled and more evenly distribution.It is the first genetic map of Cucurbita moschata pumpkin RIL populations with the highest marker density at present,which is suitable for QTL mapping analysis.2.Determination of starch,sugars,inositol and soluble solid content in Cucurbita moschata pumpkin fruitsIn this study,the two-wavelength method and the starch color method were used to determine the starch content of each parent and RIL population samples.The HPLC method was used to determine the sugar and inositol content.These phenotypic trait values showed a near normal distribution,and they were quantitative traits.A low-sugar content,highinositol germplasm resource N19 was selected.3.QTL mapping of starch,sugars and inositol in Cucurbita moschata pumpkinBased on the linkage map,composite interval mapping was used to map QTLs of starch content,sugar content and inositol content traits of Cucurbita moschata pumpkin fruit in the commercial stage.7 QTLs controlling starch traits were detected with a contribution rate of 6.22-11.33%.9 QTLs controlling sugar-related traits were detected with a contribution rate ranging from 7.15-13.55%.1 QTLs for controlling inositol content,with a contribution rate of 10.81%.