Construction And Screening Of EMS Mutant Library In Cucumber(Cucumber Sativus L.)

Cucumber?Cucumis sativus L.?belongs to Cucurbitaceae,native to the tropical rainforest in the southern Himalayas.It is one of the top ten vegetable crops in the world,an important economic vegetable crop in China.Although the geographical distribution of cucumber is broad,compared with crops of melon and pumpkin in the same family,the genetic basis of the cucumber tends to be single,the mutation frequency only 3%-8%,which greatly limits the breeding process and the excellent germplasm innovation.In this study,seeds of the high-generation inbred line'6457'was used as the experimental materials.By one time seeds treatment with EMS to constructed the cucumber mutant library,the phenotypic variation characteristics of the mutant population were analyzed.The mutants were screened using HRM-TILLING technology to broaden the genetic background of cucumber and provide basic materials for cucumber functional genomic research and breeding new varieties.The results are listed as follows:1.In this study,seeds of the high-generation inbred line'6457'were treated by ethyl methane sulfonate?EMS?solution with different concentrations of 0,0.5%,1.0%,1.5%,and 2.0%for 4h,6h,8h,10 h,and 12 h to construct the cucumber mutant library.Considering the germination rate and seedling rate,we determined 10 h,1.5%EMS as the appropriate mutagenic dosage in this experiment for'6457'.2.Then,2500 seeds were treated by 1.5%EMS for 10 h,and 1504 M₁ plants were transplanted into solar greenhouse.The plant of M₁ were crossed by itself,and a cucumber mutant library contained 221 M₂ families was constructed.Trait investigation found that variation with abnormal appearance of wrinkled leaf,variegated leaf,plant with multiple tendrils,dwarf,etiolated,albino,deformed and chimera fruit were observed in the M1 population.And numerous valuable mutant phenotypes were observed in M₂ population,including long fruit,short fruit,heart-shaped leaves,hermaphrodite flower,dwarfed plant and so on.3.221 plants were investigated in terms of agronomic and biological traits,we found 176 mutant plants with 38 mutant traits in total.The mutation rate of all M₂ is11.7%.The mutant number in leaf,flower,fruit,fruit and plant were 77,32,57,and10,respectively.The mutation rates of leaf,flower,fruit,fruit and plant were 5.1%,2.0%,3.8%,and 0.8%,respectively.4.In this study,an average of 8 plants per M₂ families were sampledand mixed.Primers were designed by using sequence information of cucumber pricking tumor gene TU and fruit color gene AP.Using HRM-TILLING technology to screen PCR amplified products,20 thorny mutants were obtained,which are M-12-7,M-14-2,M-14-3,M-21-1,M-21-8,M-22-3,M-30-6,M-34-1,M-37-9,M-54-2,M-57-2,M-89-7,M-90-1,M-98-4,M-105-7,M-105-8,M-106-9,M-135-4,M-137-1,M-181-1.And 13 fruit mutants were obtained which are M-4-2,M-14-3,M-21-1,M-22-7,M-31-1,M-33-8,M-37-4,M-49-2,M-60-6,M-75-5,M-80-2,M-132-6,M-153-3.