The Relationship Between The Number Gl Gene And Aphid-Resistant Ability Of Cucumber

Cucumber(Cucumis sativus L.,2n=2x=14)cultivation has a long history, and it is one of the worldwide vegetables. In recent years, the cucumber acreage continues to expand, it occupies a vital role in people's daily consumption. As the main pest taxa, aphids severely reduced the quality and yield of cucumber. For a long time, people relied on chemicals to control aphids, which not only easily lead to enhanced aphid resistance, and made its resistance background become more complex, but also poisoned natural enemies of aphids and destroyed the ecological balance. It was found that the glabrous mutant cucumber(glgl) had the ability of aphid-resistence, this had great potential application value in cucumber insect-resistant breeding. In order to strengthen the research on the glabrous traits of cucumber and preliminarily explore the relationship between the gl gene and its resistance to aphids, 10 kinds of materials with different ploidies which were associated with the gl gene were obtained successfully through the chromosomal ploidy manipulation technology. In addition, we compared the aphid-resistance of different materials, and the changes of the nutrients and secondary metabolites and the activities of related enzymes were analyzed dynamically before and after infection of aphids. The main research results were as follows:1. Different concentrations of mixed solution of colchicines(0.2%, 0.4%, 0.8%)and 2% dimethylsulfoxide(DMSO) were used to immerse the germinating seeds of glabrous cucumber(glgl) and normal cucumber(Gl Gl). The autotetraploid(2n=4x=28) were obtained successfully by morphological and chromosome identification. The results showed that treatment with 0.4% colchicines and 2% DMSO for 4.5 h had the highest chromosomedoubled rates of 14% and 20%. The following 10 genotypes of cucumber materials were obtained by means of hybridization and self-pollination: glgl,Glgl,Gl Gl,glglgl,Glglgl,Gl Glgl,Gl Gl Gl,glglglgl,Gl Glglgl,Gl Gl Gl Gl.2. The degree of resistance to aphids of different cucumber materials were preliminarily identified,and the resistance classification were as follows: glglglgl genotype material was highly aphid-resistant(HR) material, glglgl and glgl genotype materials were aphid-resistant(R) materials, Gl Glglgl genotype material was medium aphid-resistant(MR) material, Glglgl?Gl Glgl and Gl Gl Gl genotype materias were aphid-susceptible(S) materials, Gl Gl Gl Gl, Glgl, Gl Gl genotype materials were highly aphid- susceptible(HS) materials. The high resistance of glabrous cucumber was once again proved. The number of gl gene in cucumber was correlated with its ability of aphid-resistance: when the number of chromosomes was the same, the number of gl gene was positively correlated with the ability of aphid-resistance, and for all glabrous cucumber materials, the number of chromosomes was also positively correlated with the ability of aphid-resistance.3. The reaction degree of different cucumber materials were closely related to the ability of resistance to aphids. After aphid infestation, contents of secondary metabolites such as total phenolics, flavonoids, tannic, lignin and the activities of PAL and PPO were all increased by different degrees, and the change range was positively correlated with the resistance, but it is not completely consistent with its resistance level. In addition, the contents of protein and free amino acids of different cucumber materials were negatively correlated with their resistance. The content of protein was increased in different degrees and the increase in magnitude was positively correlated with their resistance, but it is not completely consistent with its resistance level. When the number of chromosomes was the same, the number of gl gene was positively correlated with the change range of the contents of nutrients(protein, free amino acid), secondary metabolites and the related enzyme activities, and the glabrous cucumber materials have the same rule.4. The more the number of gl gene, the stronger the ability of the aphid-resistance, which showed that the aphid-resistance was quantitative trait, and the gl gene was quantitative trait gene. Furthermore the gl gene could control stem and leaf surface character, the glabrous character was controlled by 1 pair of gl gene(glgl), so the gl gene was quality trait gene. These could concluded that the gl gene controlled not only quantitative trait but also quality trait. So the gl gene was major gene.