Compara With Pathogenicity Of Different Lophoermiun Sp. Fungi And Optimize Toxicogenic Conditions

Most of pinus are considered as pioneer species,which benefit mankind via afforestation. improvement of the ecological environment,timber supply,medical purpose and others. Lophodermium spp.fungi can cause needle cast disease to Pinus,Abies Abies,Picea,Larix, and so on,which will result in a great losses on breeding,afforestation and forest timber.In order to gain insight into the pathogenic mechanism of the toxin and pathogenicity differences of various species of fungi,cultural characteristics,toxin component and production conditions in vitro,basic nature and host-specific characteristics of the toxin,and extracellular hydrolytic enzyme activity changes of four Lophodermium spp.fungi(Lophodermium conigenum,L.pinastri,L.sichuanense and L.erlangshanense) isolated in Sichuan Province were systematically studied,expecting to obtain a basic and reliable theory for the resistance breeding of pine to needle cast and prevention and control these kinds of diseases.By comparing the growth rate of four kinds of Lophodermium spp.fungi on medium plate,all of the four fungi were found to grow fastest in wort solid medium,but display different growth patterns in different media.The growth characteristics of the four fungi in the medium plate showed that the affinity with the genetic similarity coefficient did not fully coincide.Bioassay of the bio-determination material from the needles of Pinus densata,P.armandi, P yunnanensis,P.massoniana,together with the data from conductivity of the cell membrane, showed that the four kinds of Lophodermium spp.fungal metabolites had toxic effect to the bio-materials,causing yellow spots on pine needles,death of the whole needles,and black ring lines on the Pinus armandi,P.yunnanensis,P.densata,pretty similar with the incidence and the natural symptoms.The toxic components were identified as non-protein,but not protein.The bioassay of Cedrus deodara and three kinds of weeds from different family showed that the four toxins were not host specific.Toxin production conditions were optimized for the four kinds of Lophodermium spp. fungi.The optimal conditions for toxin production of four pathogenic fungi were pH4.0-6.0, 20-23℃,12h half-light/d,stilling culture for 25d in the PD medium.A little difference observed between toxin production and hyphae growth,spore production conditions,which revealed that toxin production conditions of the four kinds of Lophodermium spp.fungi were not completely consistent with their growth conditions. Studies of the four kinds of toxin crude extracts traits showed that the four kinds of toxin crude extracts were stronger resistant to temperature under 100℃,and the pathogenicity of these toxin crude extracts decreased with increasing of temperature,but toxin activity was still detected even if temperature reached 121℃.The pathogenicity of the four kinds of toxin crude extracts decreased once pH value is above pH7.0.These toxin crude extracts had toxicity under different bioassay temperatures,but the cell membrane was damaged greater by the four kinds of bio-determination materials under alternating temperature.The four kinds of mycotoxins were larger polar substances.Chloroform:ethyl acetate:ethanol(6:3:1) was the best choice for preparation of toxin crude extracts,due to the best mobile phase with more different compositions and more reasonable Rf value.The mycotoxin components extracted from 5^th Lophodermium conigenum and the 9^th L.pinastri had more toxicity,and the 19^th L. sichuanense mycotoxin extract had the most components of the separation,but some components are not pathogenic.Therefore,we inferred that a certain differences of the four fungal toxin extracts should exist in structure and biological activity.For all of the four kinds of Lophodermium spp.Fungi,a series of cell wall degrading enzymes(CWDEs) including cellulose,hemicellulose,pectase and ligninase were found in the PD semi-sugar medium;and these enzymes's activity were difference to some degree.The 5^th fungi had the highest ability to generate extracellular CWDEs.The enzyme production of the four kinds of fungi was improved by addition of the host pine needles to the medium,and induction effect of the different types of pine needles was difference in different kinds of fungi.The pectase played an important role in the process of pine needles infection by the four kinds of fungi according to the fact of over time increase of the pectase.