| Pine needle blight caused by Pestalotia funerea,a common and serious disease in young pine forestr,has been the most important needle-leaf disease in Sichuan forest since the disease occurred in 1974 and became epidemic in 1980. The studies biological characteristics of Pestalotia funerea and its pathogenic toxin have important theoretical and practical significances to further explore pathogenic mechanism of this fungus,the occurrence and epidemical law and control method of pine needle blight. The biological characteristics of Pestalotia funerea,the traits of its toxin,the pathogenic mechanism and the chemical structure analysis of the pathogenic composition were studied in this paper. The results are as follows:1. Studies of the carbon and nitrogen screening and ecological factors showed:Pestalotia funerea,with a wide adaptability,cuold normally grow and produce spores in a wide pH scope and had a better growth under a relatively lower pH. Under the experiment conditions,Pestalotia funerea could reach its fastest growth rate(10.8mm/d) at 22-25 in the culture medium(modified Cazpek medium-1) of Fructose 30g/L KC1 0.5g/L FeSO40.01g/L K2HPO41.0g/L MgSO4 7H2O 0.5g/L peptone3.0g/L. The fungus did not grow when the temperature was above 35. It could reach the maximum production of spores on the eighth day after inoculation and in the culture medium(modified Cazpek medium-2) of Saccharose 30g/L KC1 0.5g/L FeSO4 O.Olg/L K2HPO4 1 .Og/L MgSO4 7H2O 0.5g/L KNO3 2.0g/L. Simultaneously,natural light and enough air were favorable for the fungus to produce spores. The illustration of all the characteristics made the biological foundation for further study and utilization ofPestalotia funerea.2. Studies of the toxin crude extract traits showed:The production of toxin was closely relative to the culture condition. Pestalotia funerea could reach the best production in the PD culture liquid. The addition of pine needle extract to the culture liquid could not promote the production and pathogenic characteristics of this gungus. The produced toxin,which could be adsorbed by activated charcoal and be fully extracted by methanol from its culture liquid,was not a kind of protein material. All the characteristics of toxin provide biochemical basis for thorough study of toxin.3. The different experimental materials suggested that the immature pine needle,which was quick and sensitive to toxin and produce obvious infected symptom,was the ideal material for bio-determination. Compared with the methods of soaking and applying,acupuncture was the best method for bio-determination that had the features of quick reaction to toxin and low consumption of toxin. The fact that mold did not grow on the pine needles dealt with acupuncture made the bio-determination results more direct and accurate.4. The toxin pathogenic mechanism study illustrated:Dealt with toxin,the cell membrane and lipid of the pine needles were induced to superoxidation. The change of MDA content reached its maximum (48% higher than contract) after 24hr for toxin treatment and the membranes were destroyed at last. The change of POD was the same as MDA. All these suggested that the harmful changes took place in the physiological metabolism of the host after treated with toxin and the cell membrane were destroyed in a certain degree.5. Studies of purification technique and chemical structure of the toxin showed:The preparation method using n-butanol:methanol:water (60:30:15) as the mobile phase on a gel H60 column can isolate the toxin of Pestalotia funerea. Three pathogenic materials,which were phyto-polysaccharoses with low molecular weight,were isolated from gel H60 column by n-butanol:methanol:water (60:30:15) and gradient elution of methanol aqueous solution as mobile phase. The structure of the three pathogenic materials had been detected by IR,MS and 'HNMR. The chemical composition of the pathogenicmaterial-1 is C5H11O5N (M = 165) with the structure ofThe chemical composition of the pathogenic material-1 is C10H19O10N (M=313) with the...
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