Screening Pathogenic Fungis In Chromolaena Odorata L And Its Research Of Biological Control

The Chromolaena odorata L is the Compositae perennial weed.it’s proliferates the island of Hainan,and was harmful for the agricultural production、species diversity and ecosystem security.The research results showed that is a safe way to screening and use of local plant pathogens fungi resources to control invasive species.The purpose of this research was to isolate the pathogenic fungis with higher biological activity from the Chromolaena odorata,and to research the biocontrol value of their virulence and metabolism.it’s includes the following sections.1.The investigation and sampling of the infection situation of Chromolaena odorata in some regions of Hainan.There are five main types fungal diseases.The pathogens are Alternaria sp.、Curvularia sp.、Fusarium sp.、Colletotrichum sp.、and Cercospora sp.,the most common is the angular leaf spot caused by Cercospora sp.,Leaf spot was influenced by natural environment and pathogens.Different regions had differences.2.61 strains were isolated from the regions of natural Chromolaena odorata,Select from easy to isolate and highly virulence 46 strains to virulence test,The results showed that the virulence of different strains had differences.Based on morphological characteristics and sequence alignments of rDNA ITS region the most important pathogen fungi of Chromolaena odorata were identified as Alternaria alternata、Curvularia lunata and Fusarium oxysporu.Select high virulence of 11 strains to tropical regions weeds showed that only Wedelia chinensis、Digitaria sanguinalis、Bidens pilosa、Solanum nigrum on these strains showed highly and moderately susceptible.3.The biological characteristics of strains LGB100401、WB110216 were studied.The strain LGB100401 optimal temperature for the mycelium growth was 25 ℃,the mycelium could grow optimally at pH6,the optimum carbon source is maltose,optimum nitrogen source is beef extract,light on the growth of the mycelium was not significant;The strain WB 110216 optimal temperature for the mycelium growth was 30 ℃,the mycelium could grow optimally at pH7,the optimum carbon source is sucrose,optimum nitrogen source is peptone,light on the growth of the mycelium was not significant.The suitable conditions for the toxin-producing capability of the two strain,The optimal conditions of toxin poroduction for strain LGB 100401 was 25 ℃、pH between 4-6,culture time was 15d,low speed oscillation and static culture combination;The optimal conditions of toxin poroduction for strain LGB 100401 was 20 ℃、pH between 6-8,culture time was 15d,low speed oscillation and static culture combination.4.Activity of crude toxin of strain LGB100401、WB110216 to the Chromolaena odorata,The results showed that the crude toxin of two strains has biological activity to it’s seed、root length、shoot length,it’s shows as inhibition effect.Metabolites can produce toxins and cause the Chromolaena odorata leaves necrosis.The crude toxin of the two strains weed control spectrum was studied,The results showed that the Cucumis sativus、Zea mays、Heveabrasiliensis and other crops on two strains are not sensitive,the strain LGB 100401 has a wide range of toxicity,it’s sensitive to the Tridax procumbens、Chromolaena odorata、Bidens pilosa;the strain WB110216 has little range of toxicity,only sensitive to the Chromolaena odorata.The biological activity of crude toxin of the two strains in different plant materials was studied,two strains has higher inhibitory effect to the Amaranthus retroflexus、Digitaria Sanguinalis、Bidens pilosa and safety to the Cucurbita moschata、Vigna unguiculata、Phaseolus vulgaris.5.Using macroporous resin to extract the crude toxin of two strains,silica gel column gradient elution,and collect the elution fractions.In each fractions,the biological activity was detected by using acupuncturing leaves in vitro,and combined with the detection of polarity and biological activity.The optimal elution system of the strain LGB 100401 was identified as ethyl acetate:methanol=5:2;The optimal elution system of the strain LGB 100401 was identified as petroleum ether:ethyl acetate=5:4.Two kinds of elution system to Chromolaena odorata leaves the largest disease spots.6.GC-MS analysis were performed on the crude toxin of two strains.The results showed that it’s identify many compounds including 5-hydroxymethylfurfural、TeA and also including common components of plant pathogen fungis,such as benzoic acid ester、amide、polysaccharide derivatives and carboxylic acid derivatives.