Inheritance And The QTL Mapping Of Fruit Length And Fruit Neck Length In Cucumber(Cucumis Sativus.L.)

Cucumber(Cucumis sativus L.,2n=2x=14)is an economically important vegetable crop worldwild,which originated in the southern slopes of the Himalayas.For most of us,the appearance properties of flesh fruit,such as skin color,warts,spines,fruit length(FL)and neck length(FNL)have great impacts on their choice,acceptability,and consumption.Thus,ascertain the genetic architecture and identification of the causal gene governing these traits will provides valuable information for genetic germplasm resources innovation and the new varieties breeding.In present study,the cucumber line YN(male parent,P1)and Jin5-508(female parent,P2)that showed extreme FL and FNL were selected to construct segregated populations,including F1(YNxJin5-508),B1(F1�YN),B2(FixJin5-508),and F2.The mixed major gene plus polygene inheritance model was used to analyze the waterlogging tolerance in the six generations(P1,P2,F1,B1,B2,and F2)of cucumber.The major-effect QTLs controlling FL and FNL were identified by QTL-seq.We further evaluated the candidate genes by qRT-PCR.The main results are listed as follows:1)The results showed that the genetic model E-1-1,mixed two dominance major-gene and additive-dominance polygenes,is the best-fitting genetic model for both of the two traits,FL and FNL;2)After calculation of ?(SNP-index)and ?Euclidean distance value of the two pools,a?10.36-Mb-long QTL on Chromosome 1(Chrl)controlling the FL(designated as fl1.1)and a-4.63-Mb-long QTL on Chr7 controlling the FNL(designated as fnl7.1)were identified.Through whole-genome sequencing,SNP haplotyping and fine genetic mapping,the fll.l was narrowed down to a 0.47Mb region containing 46 genes,the fn17.1was narrowed down to a 0.49Mb region containing 45 genes;3)We found the relative expression levels of CsalM537530.1,Csa1M537600.1,Csa1M538180.1,Csa1M538200.1 and Csa1M538260.1 in the 0.46Mb region were higher in Jin5-508 than YN,suggesting these genes are possible candidate genes for fl1.1 The relative expression levels of Csa7M338120.1,Csa7M341240.1,Csa7M339690.1,Csa7M341250.1,Csa7M343310.1 and Csa7M351880.1 in the 0.47Mb region were higher in Jin5-508 than YN,suggesting these genes are possible candidate for fnl7.1.