Genetic And Biochemical Characteristic Research Of Corn Resistance Ot Common Smut

Common smut was a soil-transmitted and partial infection disease. At the stage of tasseling and pollens scatteration, the disease spreads by the fastest speed, the most damage occurred at the early stage of grain-filling, until the matured, the smut tumors of maize stopped happening. The reduction extent of output depends on the infection stage of plant, forming position, quantity and size of fungus wart, usually lost 20～30%.In past, maize smut occurred slightly and most of cultivars popularized in cultivation had no resistance to maize smut. In recent years, the planting area of maize extended in successive years and serious continuous cropping. The happening tendency of maize smut is rising year by year, and the smut fungus accumulated excessively in the soil, so that the disease caused by smut has risen as the main disease in the northwest and in north China. In order to develop the germplasm resources indentification technique of corn resistance to common smut, this study took resistant maize inbred lines "178", "Qi 319", susceptible inbred lines "Zheng 58" and the reciprocal crosses F1～F2 as materials, the physiology biochemical characteristics and genetic peculiarity were studied, aimed to provide evidence for resistance breeding of corn smut tumors. The results are as following:1.Significant differences of disease resistance showed up in different genotypes disease resistant and susceptible parents, there was extremely significant difference between resistant and susceptible parent's resistance. The resistannce was consistent in the same combination of reciprocal cross, the resistance of the first hybrid generation was between their parents. In order to breeding the antitumor smut hybrid, we should base on choosing parents with strong resistance or at least one of the parent is not too bad, several F2 populations'resistance to the tumor smut have confirmed this conclusion.2.In the roots of genotype of disease resistance was infected by the smut fungus, the SOD activity, POD activity and the content of soluble protein were higher, but the soluble sugar content in non-vaccinated genotype were significantly higher than the corresponding vaccinated genotypes, the result showed that after infection, the corn consumed the soluble sugar in roots excessively; it had been consumed more in poor disease resistance genotype. In the initial stage of vaccinating, soluble sugar content in roots of disease resistance genotype was significantly lower than the susceptible genotype, but in the later stage of vaccination, soluble sugar content in root of disease resistance genotype was significantly higher than the susceptible genotype.3.No significant relationship was found between the resistance genotype and SOD, POD activity, soluble protein content in stems, but in the initial stage of vaccination, anti-tumor smut capacity of genotype could be presumed according the content of soluble sugar in stem, low content had the strong resistant, vice versa.4. After vaccinating the smut fungus, leaves prevented disease from happening by continuous and relatively stable SOD activity. The susceptible genotype infected from initial to later infection of disease, the SOD activity had a poor persistent with a violent ups and downs process. In leaves of disease-resistant variety, POD activity were higher, and the POD activity increased gradually with the extending of time, but there was no logical relationship existed between soluble sugar content in leaves and disease resistance.