Cucumber Infected With Fusarium Oxysporum Physiological And Biochemical Changes And Their Relationship With Disease Resistance Research

Studies on the relationships of some physilogical-chemical changes and disease resistance in cucumber infected with Fusarium wilt disease Abstract The activities of superoxide dismutase(SOD) peroxidease (POD) and catalyse(CAT), MDA content. relative electrical conductivity, sugar, water -soluble protein and Vc content in germinated seeds, cotyledons inoculated with Fusarium oxysporum and treated with crude extract of Fusarium wilt pathogen of cucumber cultivars with different resistance to Fusarium wilt of cucumber were measured. Meanwhile, some compounds inactivating the phytotoxicity to cucumber were studied.The results showed as follows: 1. POD and SOD activities have close correlation with the resistance of cucumber cultivars both in germinated seeds and in roots or leaves of cucumber in cotyledons. 2. Resistant cultivars, compared with susceptible cultivars, display low range of SOD, POD CAT activity and membrane lipid peroxidation and relative electrical conductivity between treatment and control,. 3. Sugar, soluble protein and Vc content have close correlation with the resistance of cucumber cultivars in roots or leaves of cucumber in cotyledons . Resistant cultivars, compared with susceptible cultivars,have high sugar, soluble protein and Vc content. 4. Changes of the activities of superoxide dismutase(SOD). peroxidease (POD) and catalyse(CAT), MDA content, relative electrical conductivity,. sugar, water -soluble protein and Vc content in roots are more distinct than those in leaves when cucumber was inoculated with Fusarium oxysporum. 5. Toxin produced after cucumber inoculated with Fusariuni wilt pathogen was one of main pathogenic factors.There were high membrane lipid peroxidation and relative electrical conductivity after cucumber is treated with 50% toxin crude extract. 6. There were changes in the SOD and POD isozyme bands of inoculation and toxin treatment among different resistant cucumber cultivars . Isozyme bands of resistant cultivars are stronger than susceptible cultivars, compared with respective control. 7. KMnO4. CuSO4. FeCL3 can reduce the phytotoxicity of crude extract of cucumber wilt disease. Among these compounds, KMnO4 has best effect.