Study On The Biological Characters And Biocontrol Of Sclerotinia Sclerotiniorum In Heilongjiang China

Sclerotinia sclerotiorum (Lib) de Bary is a Ascomycete with a wide host rangeS and geographical distribution, which is one of the most non-specific, omnivoroes and successful plant pathogens. In resent years, the outbreak of Sclerotinia sclerotiorum, also called sclerotium, more and more severe in northeast soybean plant areas. The objective of the study was to identify morphology, biochemistry and pathogenicity of the sclerotium isolated from different areas in northeast of China and the biocontrol effect of Trichoderma spp. to sclerotium by antagonistic on plates and field experiments, to show the main various sclerotium isolates and biocontrol effect of Trichoderma viride Pers. in northeast different areas. The results provided theory basis for soybean safety product. Main experiments and acquired results like these:The results showed Sclerotinia sclerotiorum (Lib) de Bary chacteristics and the negative effects of agronomic traits for inoculated hosts in northeat soybean areas; It supplied mang research methods for sclerotium inoculated hosts.Analysis results of Sclerotinia sclerotiorum morphology character collected from different norheast ecological zones showed that it was discrepancy and toxicity similar. Sclerotium acquired from Hailun city can form close roundly colony, however, acquired from Jiamu Si city form uneven and discrete colony first, and then form ring-shaped colony by sclerotium at the marginal zone or near edge of culture dish. Hypha abundance of Hailun city was higher than acquired Jiamu Si city significantly, and sclerotia acquired from Hailun city are bigger than Jiamu Si city. Results of exsomatize oxalic acid test showed that isolates toxicity from two areas may be similar.Results of exsomatized leaves inoculation and pot experiments showed that whole soybean leaves would be decomposed by Sclerotinia sclerotiorum (Lib) de Bary hypha after inoculated 30d; pot experiments results indicated that mycelium appears when soybean has two leaves and after 16d hypha block appears. Kernel weight, coarse fat and coarse prote content of infected soybean all declined, and coarse content declined more than coarse protein content. Amino acid gross and ammonia peak value have the same trend with them. Disease severity index (DSI) and pathopoiesia of physiological race of Sclerotinia sclerotiorum (Lib) de Bary were various greatly among different areas, besides disease severity index (DSI) and lesion length has positive correlation. It is suitable that identify at the stage of growth up as the standard of species resistance to the disease.Roundly researched on the biocontrol effects of biocontrol bacteria on soybean sclerotium by combined methods of laboratory and yield supplied maneuverability experimental model for sclerotium biocontrol.Results of pot experiments and on PDA plates showed that Trichoderma viride Pers. can inhibit Sclerotinia sclerotiorum (Lib) de Bary significantly; the effect of application biocontrol agent on wind-sand soil was better than other types of soil. With the soybean growth, the effect of biocontrol agent declined gradually; Application of potassium fertilizer can inhibit the growth of Sclerotinia sclerotiorum (Lib) de Bary. With the increase application of biocontrol agent, incidence of the disease declined on black soil and wind-sand soil, it can reduce the incidence of field significantly, but hasn't great effect to yield on wind-sand soil.Groping a molecular biology operationg system for protoplast preparated by Sclerotinia sclerotiorum (Lib) de Bary hypha and translated, built examination platform for biocontrol mechanism studies.It was difficult to identify the hypha of Trichoderma viride Pers or Sclerotinia sclerotiorum (Lib) de Bary, and illustrate their inhibition, so that composing gene expressing carrier pPGT which has GFP. It was succeeded to transfer the GFP gene to pathogen fungal Sclerotium by the method of protoplast transformation with PEG. Results of Southern hybridize indicated that GFP gene has been integrated to Sclerotium genesis DNA. It proved that GFP gene could be expressed in Sclerotium successfully, and could inherit steadily. Antagonistic experiments proved that Trichoderma viride Pers could inhibit Sclerotinia sclerotiorum (Lib) de Bary observed under the fluorescence microscope.Base on the study of pathogen isolates morphology characters and pathopoiesia in different northeast ecological zones, supplied more materials for the studies of sclerotium occur discipline and soybean resist disease breeding. The biocontrol study of Trichoderma viride Pers to soybean sclerotium provided necessary measures for northeast soybean safety products.