Fine Mapping And Functional Analysis Of The Candidate Gene For Multiple Pistillate Flowers In Cucumber

Cucumber(Cucumis sativus L.)is one of the main vegetable crops cultivated in China.Cucumber is one of the top ten vegetables in the world,which originated in southern India at the southern foot of the Himalayas and is suitable for spring and autumn cultivation.Cucumber is usually monoecious with one pistillate flower at each node,but there are some cucumber materials with two or more pistillate flowers at the same node,which is called multiple pistillate flowers trait.In this study,PI500365(hard epidermis with black prickle tumor)and PI422180(smooth epidermis without prickle tumor)were used as male parents to breed BC1F2 population.The genetic analysis and gene mapping of genes controlling multiple pistillate characters in cucumber were studied.The main results are as follows:1.Through the field phenotypic statistics of four generations of male parent pi500365 and pistillate parent PI422180,and the genetic analysis of pistillate flower node rate of cucumber,the results showed that the multiple pistillate character of cucumber was dominant or incomplete dominant.At the same time,the frequency distribution of the average value of pistillate flower node rate in BC1F2 population was partial normal distribution,and the multiple pistillate inheritance of cucumber had the characteristics of quantitative inheritance.2.QTL-Seq mapping method was used to construct an extreme mixed pool to map the major QTL controlling multiple pistillate in cucumber.In this study,two extreme mixed pools were constructed,and a major QTL with a physical distance of 400 kbwas located on Cucumber Chr6.According to cucumber Gy 14_Two candidate genes were predicted in the 400 kb region of V2 reference genome.The candidate gene was cloned and sequenced in the parent establishment.It was found that 10,a gene encoding ACC oxidase,was the key candidate gene.The difference of multiple pistillates in Cucumber might be the exon Diox of CsGy6G013010_A nonsynonymous mutation in the N domain region results in the mutation.3.The candidate gene CsGy6G013010 was verified by QRT PCR.It was found that the expression level of CsGy6G013010 was the highest in stigma and petal,and the expression level of CsGy6G013010 in multiple pistillate parents was higher than that in single pistillate parents.Exogenous silver nitrate treatment significantly reduced the pistillate node rate and inhibited the expression of CsGy6G013010.