Studies On Colletotrichum Capsici F.nicotianae Toxin Inactivator And Its Functional Mechanism

Tobacco Black Death Disease is one of the important tobacco diseases in Shandong Province. In 1995, Zhang Guangmin firstly certified that Colletotr -ichum capsici ?nicotianae could produce toxin-like substance causing tobacco seedling wilting quickly and leaf withering. So further studies on Colletotrichum capsici f ni cotianae toxin inactivator and its functional mechanism are of great significance and provide people with a new thoughtway on the innoxious prevention and cure of Tobacco Black Death Disease. This paper made studies on screening out inactivators of toxin, effects of the inactivators on hyphal growth and conidiophore germination, effects of the rough toxin system on membrane permeability and activity of five defensive enzymes in tobacco leaf, effects of the rough-toxin system on organic ultrastructure of tobacco leaf and effects of prevention and cure of the mixed liquid system of spore suspension and compounds on Colletotrichum capsici f. nicotianae in the greenhouse. The results showed that:1. The screening of toxin inactivators: 4 chemical compounds were screened out from the 16 ones with the method of lamina pinpricking in vitro. They were KMnO4. NaOH, KI and NaHCO3 which inactivated the toxin strongly.2. Effects of the inactivators on hyphal growth: 4 chemical compounds were screened out from 17 ones. They were NaOH, CuSO4, NaHCO3 and thiophanate-methyl (70%) which restrained the hyphal growth of Colletotric -hum capsici f. nicotianae strongly.3. Effects of the inactivators on conidiophore germination: 3 chemicalcompounds were screened out from 8 compounds. They were CuSO4 NaOH and NaHCO3 which restrained the conidiophore germination strongly. And maltose and glucose promoted the conidiophcre germination of Colletotrich-um capsici f. nicotianae obviously.4. Effects of the rough toxin system on nembrane permeability: Colletot -richum capsici f. nicotianae toxin could increase the cell permeability of tobacpo leaf, which caused electrolyte leakage and in the experiment, the toxin was detoxified by NaOH2000ug/ml and NaOH5000ug/ml strongly and the cell membrane electrolyte leakage could decrease after the treatment.5. Effects of five defensive enzymes activity in tobacco leaf: After treated by the rough toxin system, the changes of the five defensive enzyme activity of tobacco leaf were detected.5.1 Effects of CAT activity after treated by the rough toxin system: After the treatment of T+NaOH2000ug/ml, the CAT activity ascended inearly time (6h-24h) and then descended .The CAT activity was lower than that of the control and the toxin treatment in all; After the treatment of T+NaOH 5000ug/ml, CAT activity ascended firstly dur ng the time (6h-48h) and then descended.5.2 Effects of POD activity after treated by the rough toxin system: After the treatment of T+NaOH2000ug/ml, the POD activity ascendedslowly before 60h and reached the peak at 60h; After the treatment of T+ NaOH5000ug/ml, POD activity ascended slowly all the time and was higher than that of the control and the toxin treatment.5.3 Effects of PAL activity after treated by the rough toxin system: After the treatment of T+NaOH2000ug/ml, the PAL activity ascendedbetween 12h and 48h and reached the peak at 48h and subsequently descended quickly and reached the lowest point at 60h. PAL activity was higher than that of the control and the toxin treatment in all; After the treatment of T+NaOH 5000ug/ml, PAL activity ascended slowly between 12h and 36h and reached the peak at 36h and then descended slowly. PaL activity was higher than thatof the control and the toxin treatment in all.5.4 Effects of PPO activity after treated by the rough toxin system: After the treatment of T+NaOH2000ug/ml, PPO activity descended inearly time(6h-12h) and subsequently ascended during the time(12h-24h) and reached the peak at 24h. PPO activity was higher than that of the control and the toxin treatment in all; After the treatment of T+NaOH5000ug/ml, PPO activity ascended slowly during the time (6h-60h) and reached the peak at 60h. PP...