Studies On EMS Mutagenesis And Creation Of Mutants In Cabbage

Cabbage（Brassica oleracea var.capitata L.）is an important vegetable of the cruciferous family and brassica,which is in great demand in domestic and foreign markets.However,the germplasm resources of cabbage in China in terms of leaf bulb traits and salinity resistance are relatively scarce,and it is necessary to create new leaf bulb traits and salinity-resistant cabbage germplasm.Ethyl methanesulfonate（EMS）is a chemical mutagen with relatively successful applications and is widely used in vegetable mutagenesis breeding.In this study,the seeds of‘AP38’and‘AP47’cabbage inbred lines were treated with different concentrations of EMS,and the plants with leaf bulb mutations were screened in the‘AP38’M₂ generation and the salinity-tolerant mutants in the‘AP47’M₂generation plants,so as to create new breeding materials for the breeding of cabbage,in order to accelerate the creation process of new cabbage varieties.The results were as follows:1.The cabbage seeds were soaked by EMS at different concentrations（CK,0.2%,0.4%,0.6%,0.8%and 1.0%）for 4 h,8 h and 12 h.The seed germination ability of‘AP38’and‘AP47’decreased significantly.The semi-lethal concentration and time of EMS treatment on seeds were（0.8%,12h）and（1%,8 h）,respectively.The contents of proline and MDA increased significantly,the activities of SOD and POD increased at low concentration,and decreased significantly when the concentration exceeded half lethal dose,and the physiological metabolism was affected significantly.2.Morphological screening and molecular identification were carried out on the mutant offspring of‘AP38’population,among which there was no significant difference between M₁ generation and the control.After field screening identification in M₂ generation,207 plants with mutant leaf bulb characteristics were screened,including 84 plants with non-heading materials,61 plants with lobular materials,35plants with pointed spherical materials,10 plants with long rod-shaped leaf bulbs and17 plants with degenerated leaves..3.The seedlings of‘AP47’M₂ generation were treated with different concentrations of saline and alkali solution hydroponically for 4 weeks,it was found that the plant height,root length,fresh weight and dry weight of the seedlings were significantly decreased,while the contents of cell membrane permeability,MDA and osmotic regulatory substances were significantly increased,and the root activity and plant photosynthetic rate were significantly decreased.Through the correlation analysis of different indexes,it was found that total fresh weight was significantly positively correlated with morphological indexes such as plant height,root length,above-ground fresh weight,underground fresh weight,above-ground dry weight,underground dry weight and total dry weight,and significantly negatively correlated with physiological indexes such as relative electrical conductivity,malondialdehyde,proline and soluble sugar,and significantly positively correlated with photosynthetic parameters such as chlorophyll and net photosynthetic rate.A total of 9 saline-alkali resistant plants were obtained by ISSR identification,among which 7 were saline-alkali resistant mutants of medium concentration and 2 were saline-alkali resistant mutants of high concentration.