The Study On Inducing Low-Temperature-Resistant Mutants Of Tomato With Chemical Mutagen

Low-temperature-resistant materials were obtained through seed germination index and seedling chilling resistance index,the high frequency and timesaving regeneration system was established, the Semi-lethal dose(LD50) and the appropriate processing time was determined by the callus survival rate.And the regeneration plants were obtained by cryogenic stress.The main results were as follows:1.Identificating and selecting low-temperature-resistant materials of tomatoThe appraised index at seed germination stage was germination index at 15℃and the appraised index at seedling stage was chilling injury index at 2℃. 9 tomato materials with significant differences on germination index at 15℃were screened out from 79 tomato materials. the highest index was 2.9 and the lowest was 0.0. Low-temperature-resistant tomato variety namely FTI1115A was obtained by the chilling resistance index at low temperature (2℃) treatment for 48h. The results showed that there were significant differences among the 9 materials on the chilling resistance index,the highest was 2.66 and the lowest was 1.54 .2. Establishment of high efficient regeneration system of tomato material with tolerance to low temperatureThe effects of 9 different hormone combinations of 6-BA and IAA on inducing callus, buds, roots and transplanting seedlings were studied by using the hypocotyl of tomato low-temperature-resistant cultivar FTI1115A as explants to establish the efficient regeneration system laying a good foundation for mutagenic breeding. The results showed that there were significant differences on callus inducing and shoot differentiation among different hormones combinations. The best medium for callus culture was MS+3.0mgL^-16-BA+0.2mgL^-1IAA. The best medium for bud induction was MS+2.0mgL^-16-BA+0.1mgL^-1IAA. The optimum rooting medium was MS+IAA 0.2mgL^-1.3. Determining the semi-lethal dose and the appropriate processing timeCallus of totamo variety'FTI1115A'were treated with different concentrations of ethyl methane sulphonate (EMS) and sodium azide (NaN3) for different time to determine the semi-lethal dose and the appropriate processing time by the callus survival rate.The results showed that the survival rate of callus decreased with treated time at the same chemical mutagenesis concentration, meanwhile, the survival rate of callus dropped down by the chemical mutagenesis concentration at the same time treatment. semi-lethal dose of EMS was 0.2% concentration for 20-40min, and NaN3 was 3.0mmol/L concentration for 40-60min .4. Inducing low-temperature-resistant mutants of tomato with chemical mutagenCallus of totamo variety'FTI1115A'were treated with the semi-lethal dose and the appropriate processing time and transferred to the callus culture medium of (MS+3.0mgL^-16-BA+0.2mg·L^-1IAA) at low temperature (10℃) for 48h, then the live callus was moved to the medium (MS+2.0mgL^-16-BA+0.1mgL^-1IAA) for bud induction and to the medium (MS+0.1mgL^-1IAA) for rooting under normal temperature (25℃), to get the regeneration plant . The results showed that chemical mutagen could lengthen the shoot and adventitious roots differentiation time and reduce the regeneration frequency. There were some performances of regeneratived plants including leaf shrinks, thinner, branching, slow growing or stagnation. Three plants were induced through the ethyl methane sulphonate (EMS) treatment and eight plants were obtained by sodium azide (NaN3) treatment.