Identification Of Cucumber Root Dysplasia Mutant And Its Candidate Gene

Cucumber(Cucumis sativus L.2n = 2x = 14)is a muskmelon plant of cucurbitaceae,which is the main vegetable crop in the world and one of the vegetable crops widely cultivated in China.As the vegetative organ of plant,root plays an important role in the whole process of plant growth and development.As an important part of cucumber plant,root can absorb nutrients and water.The phenotype of cucumber root dysplasia is an ideal trait for studying root development mechanism and cultivating excellent varieties,but there are few reports about it.This research in the prophase construction of cucumber EMS mutagenesis mutant library constructed on the basis of cucumber root EMS mutagenesis dysplasia mutants‘Csrod(Cucumis sativus root dysplasia)' M3 generation of genetic group,on the phenotypic characterization and genetic analysis,and by using the Mut Map+technology mutation phenotype and wild phenotypic mixing pool heavy sequencing analysis respectively,the root dysplasia candidate genes has carried on the preliminary screening,using the KASP genotyping techniques for candidate SNP identified in M3 generation group,Finally,the candidate gene of EMS mutagenesis root abnormality was determined.The main results are as follows:(1)The results of phenotypic identification showed that the mutant ‘Csrod' of cucumber root dysplasia was significantly different from the wild type in root elongation and other aspects.The root of the mutant ‘Csrod' with abnormal root development was slower than that of the wild type,and could only grow to 1-2 cm,and the plant grew to about 14 days.The root and cotyledon were separated,and it was a lethal phenotype.(2)In order to identify candidate genes of ‘Csrod',a mutant with abnormal root development in cucumber,individual plants of M2 generation of wild-type phenotype were self-crossed to obtain M3 generation population.Among them,11 plants of M3 population with trait segregation were single plants of mutant phenotype,and 93 plants showed wild-type phenotype.Using Mut Map+method for extreme characters mixing pool sequencing analysis,selection of mutation phenotype in M3 generation plant 11 strains and wild type phenotype of 34 strains,extraction amount of DNA are mixed,respectively build mutation pool surface type and wild type phenotypic pool to mix pool sequencing,and compare the cucumber genome sequence,on the basis of SNP-index and mutations of genes on comprehensive analysis of the influence of filter on cucumber five candidate SNPs locus on chromosome 3,four candidate SNPs located in gene exon region,the other one candidate SNPs are located in the termination codon area.Combined with KASP genotypingtechnology,it was found that the SNP genotype with the gene ID of Csa3G104930 contained in M3 generation population was co-isolated with the single plant phenotype of M3 population,indicating that Csa3G104930 was a candidate gene for regulating cucumber root development abnormalities.Sequence analysis results show that the 3876 bp Csa3G104930 gene,encoding 831 amino acids,participate in the 3-DNA-D-mannose-eight sulfonate synthetase and acyl neuraminic acid protein family of cytidine acyltransferase synthesis,so the cucumber root dysplasia mutant gene candidates named Cscks(Cucumis sativus CMP-KDO synthetase).In this study,a new gene involved in the regulation of cucumber root development was preliminarily identified,and its gene function was preliminarily discussed.In the next step,the function and molecular mechanism of this gene were further studied,so as to provide reference for studies on cucumber nutritional growth and new variety cultivation.