Abstract:

Producing mutants by EMS treatment can create novel germplasm for breeding and novel mutants for gene cloning. In this study，seeds of‘Ligeer 87-5’tomato were treated with 1% ethyl methane sulfonate（EMS）for 12 h. 240 plants were investigated in terms of agronomic and biological traits. Parts of M₃ plants were verified for genetic stability. Numerous valuable mutant phenotypes were observed in M₂ progeny，including premature aging，dwarf，round fruit，low ascorbic acid content，spots，green stem，cluster growth. Taken together the plant growth and fruit quality in M₂ fruits，we found 90 mutant plants with 50 mutant traits in total. The 13 mutant plants had two or more mutant traits simultaneously. The mutation rate of all M₂ is 8.80%（mutant lines/total lines）. The mutant number in leaf，stem，floral organ，fruit and plant habit were 27，7，17，56 and 21，respectively. The mutation rates of leaf，stem floral organ，fruit and plant were 2.64%，0.68%，1.66%，5.47% and 2.05%，respectively. A dwarf mutant gene has been identified as the mutation in curl-3 leading to nucleotide conversion of C → T，and amino acid conversion of L→F. Spraying of brassinosteroid could not restore tomato growth，indicating the curl-3 mutation disrupted brassinosteroid signaling process. The ascorbic acid content in leaves and fruits of curl-3 mutant was significantly lower than those in wild-type，with a higher ratio of DHA/AsA ratio. The expression of AO gene in curl-3 mutant leaves significantly increased. AO enzyme activity of curl-3 mutant leaves was significantly enhanced.

Key words: tomato, ethylmethane sulfonate, mutant, mutation frequency