Screening And Identification Of Cucumber "406" Mutants Induced By EMS

Chemical mutagenesis breeding has a unique effect on the improvement of crop varieties.Induced mutant has a similar genetic background, causing single gene mutation; it is easy to create the excellent germplasm resources and to study the function of the gene. Cucumber (Cucumis sativus L.; 2n=14) belongs to Cucurbitaceae, its genome is about 350M. Cucumber is one of the main vegetable crops widely grown all over the world. But the research on functional genes is so less.Ethyl methane sulfonate (EMS) has been widely used in the research of gene function of crop mutation to create new materials. But cucumber saturated mutant library hasn't been built. In this study, seeds of a cucumber inbreed line (406), were treated by different EMS does for 12h (hours) to optimize EMS mutagenesis. Considering half lethal dose and other experimentation factors,1.5% EMS was selected out as the appropriate treatment condition in this experiment. Then,10000 seeds were treated by 1.5% EMS for 12 h, and 5400 M1 plants were transplanted into solar greenhouse. Among the M1s, plants with weak, dwarfing, chlorophyll defects and other abnormalities were found. The first true leaf showed physiological damage, such as wrinkled leaf, not stretching.552 M2 family generations were obtained from M1 selfing. Each family was planted with 15-20, but part of the family only planted a few. A field survey of the whole growth period of the 5051 mutants revealed 631 morphological mutations. The total rate of mutation was 12.49%, and the mutation frequency of the leaves was the highest, followed by the fruit. According to the mutation of phenotypic differences can be classified as leaves, flowers, fruit, plant type 4 mutation types, various types of mutations, mutation frequencies are as follows:1. Leaf mutant overall mutation rate of up to 33.60%, primarily changes in leaf color and leaf shape. Leaf color mutant mainly show light yellow, yellow, new leaf chlorosis of older leaves normal, light green, dark green, etc. leaf blade mainly to change shape, such as heart-shaped leaves, nearly oval leaves, chrysanthemum leaves.2. The flower mutation rate was 16.96%, which mainly affected the morphology and color of flower, such as petal size and color, the sepal variation, clustered male, bisexual flowers, multiple pistillate flowers and other mutants. A total of 2 androecious strains were found in the sex expression of the plant.3. Fruit mutation rate was 26.94%, which mainly caused the mutation of the color and morphology. Such as light yellow fruit, yellow-green fruit, light green fruit, dark green fruit, short fruit, elongated fruit, long bundle fruit, bluntly round bundle fruit, smooth skin texture fruit, glossy skin fruits, etc.4. Plant mutation rate of 22.5%, caused mainly compact plant, dwarf, branch, and shorten internodes, bush plant, clustered tendril, and white-green stem and so on.5. On the M3 generation, most of the M2 generation mutants can be stably inherited. Short fruit mutants, light green fruit mutants were separately crossed with wild-type to construct F2 segregation population and genetic analysis indicated that the short fruit gene, light green fruit gene are a single recessive gene.