Screening And Identifying The Salt-tolerant Mutants Of Processing Tomato Induced By Ethyl Methane Sulfonate(EMS)

Salt stress is one of the main abiotic stresses in the growth of horticultural plants, the yield and the growth of tomato were significantly decreased under the saline environment.Breeding new varieties with strong salt tolerance and good comprehensive properties is an important target in tomato breeding. The research in processing tomato varieties “JW9” mutated as raw materials, using different concentrations of chemical mutagen EMS(Ethyl Methane Sulfonate) mutagenesis processing tomato seeds, according to seed germination, screening the half lethal dose of EMS mutagenesis tomato seeds.Screening and identification of salt tolerant mutants by phenotypic identification, directional screening, molecular marker method from subgeneration population, to establish the technology system of screening and identificating tomato salt tolerance mutant. The results are as follows:1.Effect of EMS mutagenesis on seed germination of processing tomato seeds: Using different concentrations of EMS treating tomato seeds, the seed germination level was inhibited by varying degrees, with the increase of EMS concentration and treat time, the inhibitory effect was enhanced. The half lethal dose of EMS mutagenesis processing tomato "JW9" is determined at 3% 10 h by measuring the germination rate, germination potential, germination index.2. Screening salt-tolerant mutant on seed germination period: According to the level of seeds germination under salt stress,screen out parent materials’ suitable concentration, semi lethal concentration and lethal concentration variation range were 64.82~70.07 mmol/L, 85.62~93.89 mmol/L,106.41~117.12mmol/L. The suitable salt concentration for screening salt tolerant mutant was determined as 90mmol/L in M3 on seed germination period; Based on the material of M3 seed germination level of the comprehensive evaluation, screened 13 mutants that salt tolerance is better than parent material; The study also showed that the germination potential, germination rate, germination index, vigor index,radicle length and hypocotyl length can be as the screening of salt tolerance evaluation index system on seedlings period.3. Screening salt-tolerant mutant on seedlings period: The use of NaCl with different concentration treating tomato seedlings showed that with the increase of salt concentration, SOD and POD and APX activity increased at first and then decreased, soluble protein, proline content generally increased, MDA content and electrical conductivity also showed an upward trend in leaves of processing tomato seedlings,the results show that in a certain range of salt stress, tomato could improve the antioxidant enzymes activity and accumulation of osmolytes to resist salt stress injury. According to the parent materials,determined 150mmol/L is the proper salt stress concentration for screening M3 salt tolerant mutant.Through determination and comprehensive evaluation of M3 seedlings in physiological and biochemical indicators, screened 16 salt tolerant materials. The experiment also shows that SOD, POD,CAT, APX, proline, MDA content and conductivity can be as the screening of salt tolerance evaluationindex system on seed germination period.4.Molecular detection of salt tolerant mutant using PCR-SSCP: Through the phenotypic identification, 521 salt tolerance materials were screened in M2 under salt stress condition. Using 23 pairs of primers for SSCP molecular detection, 5 pairs of primers in 26 materials detected 31 polymorphic loci,the average of each material produced 1.2 polymorphic loci. EMS induce mutation frequency was 2.6%.Using SSCP to detect polymorphism and there is no polymorphism between parent materials and salt tolerant materials in M3.