Studies On The Toxin Of Pestalotiopsis Funerea

The pine needle blight caused by Pestalotiopsis funerea, a common and serious disease in young pine forest, has been the most important needle-leaf disease in Sichuan forest since the disease occurred in 1974 and became epidemic in 1980. The toxin production condition of P. funerea, the basic nature and host-specific characteristic of the toxin, the pathogenic mechanism of the toxin to host cell membrane, the effect of the toxin on the ultra-structure of cell in various resistant pines, and the purification and chemical structure analysis of the pathogenic composition were systematically studied hi this paper for the first time. These studies may result in understanding the pathogenic mechanism of the toxin, the resistant reaction of various pines to the toxin and the pathogenic composition of the toxin, and further a theory basis for the resistance breeding of pine to needle blight and scientific utilization of the resistant pines are expected to obtain.21 strain of P. funerea, toxin of which had obvious diversity in pathogenicity, were isolated by single spore method from 8 pines distributed in Sichuan. Pf-1 , stronger virulence, among 21 strain, was screened out to explore toxin production condition of P. funerea, with the cut-root-seedling of Pinus massoniana f,armandi, P.tabulaeformis, Ryunnanensis, P.elliottii, P.taeda,P.radiata and P.thunbergii as bio-determination materials. The fungus could reach the maximum toxin production in PD medium out of 7 tested culture liquid media, but the addition of pine needle extract to PD could not promote the toxin production and pathogenicity of this fungus. The fittest toxin production conditions of p. funerea were 18-22C , pH 6.5-7.0,dark,stilling culture for 15-27d, and there were a little difference between toxin production and hyphae growth, spore production conditions, that revealed that toxin production conditions of P. funerea were not completely in accord with those of growth of the fungus.Studies of the toxin crude extract traits showed: (1) The toxin crude extract was stronger resistant to less than 80C but the pathogenic composition of toxin crude extract was decomposed in high temperature condition(90-100C) , and pH 4-9 did not significantly affect the virulence of the toxin crude extract. (2) The toxin was not dissolved in non-polar solvent, such as ethyl acetate, but was dissolved in the higher-polar solvent, such as alcohol,methanol . With the solvents of various proportions of chloroform to methanol as extract solvents, the higher the proportion of methanol was, the stronger the pathogenicity of toxin extract was, therefore, it should be presumed that the toxin produced by P. funerea could be a higher-polar substance. The toxin, which could be absorbed 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 provided biochemical basis for thorough study of toxin.12 arbor plants and 15 weeds from various families or genus were selected to study specification of toxin from P. funerea to host, the result showed that in pines, P. massoniana , P.tabulaeformis and P.yunnanensis were the most sensible to the toxin, P.elliottii , P.taeda for taking second place, and P.armandi, P.radiata and P.thunbergii were stronger resistant to the toxin, meanwhile, the various sensibilities of Cryptomeria fortunei, Cunningghamia lanceolata, Araucaria cunninghammi and Eucalyptus globules to the toxin were proved, these studies implied that the toxin belonged to a non-host specification toxin(NHST). On the other hand, the different bio-determination materials suggested that the immature pine needle, which was quick and sensitive to toxin and produced 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 acupunctu...