EMS Mutagenic Cucumber Mutant Construction And Phenotypic Analysis

Cucumber（Cucumis sativus L.）belongs to the genus Cucumis in Cucurbitaceae family and is one of major vegetable crops in the world.After a long cultivation history,long-term natural selection and artificial selection,the genetic differences between varieties become smaller and the genetic diversity is insufficient in cucumber.Creating high-quality mutants and constructing excellent germplasm resources can provide new germplasm materials for cucumber breeding and promote cucumber germplasm innovation.In this study,cucumber HS9320 was used as the material,Cucumber seeds were treated with different concentrations of ethyl methane sulfonate（ethyl methane sulfonate,EMS）mutagens to determine the optimal concentration for EMS treatment,the mutations of M₁ and M₂ generation mutants were analyzed and screened,and the important traits mutants were obtained,and the EMS mutant library was established for the screening of drought-tolerant and salt-tolerant mutants,which laid an important foundation for the breeding of new cucumber varieties and the study of important traits.The main findings of the paper are as follows:1.Cucumber HS9320 seeds was treated with 6 EMS concentrations（0%,0.4%,0.8%,1.2%,1.6%,2.0%）,and the semi-lethal concentration was determined according to the seed germination rate and seedling rate,and finally the optimal mutagenesis conditions of 1.2%EMS for’HS9320’were obtained.2.Using the above optimal mutagenesis concentration to treat 4000’HS9320’seeds,1637single plants constituted M₁generation plants.Among them 942 plants obtained self-pollinated seeds.The main variation was found in leaf color chimera,fruit conjoination,extremely dwarf plants,and early flowering period.3.The whole growth period traits of 2275 M₂ generation plants were observed and statistical,and the total variation rate was 39.44%,including 79 typical mutation types,such as monocots,tricotyledons,true leaf yellowing,tendril pairs,amphoteric flowers,and male flower 6-petals,among which the mutation rate of male 6-petal petals was as high as 11.08%,and the mutation rate of plant flat stems was the lowest 0.04%.4.20%PEG-6000 was used to evaluate the drought tolerance of 1052 cucumber m utant materials at the germination stage,and 3 high drought-tolerant mutant materials,ac counting for 0.28%;59 drought-tolerant mutant materials,accounting for 5.60%;There w ere 56 medium-drought-tolerant mutant materials,accounting for 5.30%;584 copies of se nsitive mutant materials,accounting for 55.5%;There were 350 sensitive mutant material s,accounting for 33.2%.5.The salt tolerance of 1052 cucumber mutant materials was evaluated by 250mmol/LNa Cl solution,and 1 part of the mutant material with high salt resistance（?）i≥0.8 was obtained,accounting for 0.095%;15 and 50 copies of 0.6≤（?）i<0.8 and 0.4≤（?）i<0.6 of medium salt-tolerant mutant materials were found,accounting for 1.42%and 4.75%,respectively.The remaining 986 mutant materials were more sensitive and sensitive,accounting for 93.72%.