Colonization In Special Organic Fertilizer And Bio-control Of Trichoderma Harzianum Strain Psn86 Against Ginseng Rust Rot

Panax ginseng C.A.Meyer,belonging to the Araliaceae genus,is one of the main economic medical crops and has a high value of medicine in China for a long time.Its re-plantation in continuous cropping usually fails and it takes up to 20 years for previously cultivated ginseng fields to recover.The national law of china prohibits people from reclaiming lands for growing ginseng from new forests.Therefore,growing ginseng in farmlands becomes an inevitable trend.Multiple pathogenic fungal exist in soil,increasing the occurrence of ginseng diseases and the difficulty of prevention,in turn causing serious losses on quality and yield of ginseng.In ecologic system,all living beings depend on each other with mutual restraints.Trichoderma is a genus of antagonistic fungi that is widely adopted for plant diseases by biological control.In recent years,bio-organic fertilizer obtained after the secondary fermentation of compounds formed by combining one or more microorganisms that adjust plant growth,improve the soil,and fight against soil-borne microbial pathogens with traditional organic fertilizer is well-received.This paper studied about biological features of the T.harzianum（Psn86）,suppression on Cylindrocarpon destructans,GFP marks and colonies,colonies developed in soils and organic fertilizer,and impacts of compound organic fertilizer on the defensive enzyme system of the ginseng.The study results provided a theoretical basis for the disease control mechanism and promote the application of T.Harzianum（Psn86）.1.Main biological characteristics of biocontrol bacterium T.harzianum（Psn86）.Studies showed that the most suitable medium for growing mycelia of T.harzianum（Psn86）was PSA and for spores was PDA.The most suitable pH value for cultivating both mycelia and spores is 6,the optimal culture temperature is 30℃,the best carbon source is sucrose,the best nitrogen source is beef extract,and the cultivation time is 3 d.The mycelia grow fast in all dark condition while illumination is favoured by spores.2.Suppression on C.destructans.Through confrontation cultivation,suppression on C.destructans is studied.The results show that the temperature affects the effect of suppression.Under the temperature of 20℃,the suppression rate is 75.82%.Under the temperature of25℃,the suppression rate is 81.33%.The effect of potting experiments shows that the control efficiency of the treatment group in the preventive experiment is obviously better than that of the treatment group in the therapeutic experiment.The inhibition ability of T.harzianum（Psn86）was not significantly affected by the subculture.3.GFP labeling and colonization tracer of T.harzianum Psn86 and its colonization in soil and organic fertilize.Through the agrobacterium-mediated genetic transformation technology of fungi,plasmid AGL-1 with the hygromycin gene and gfp gene is successfully moved to strain of T.harzianum（Psn86）and become transformant Psn86-g.The transformant Psn86-g obtained in this experiment has genetic stability and strong fluorescence.After comparison between mycelia and spores generated by transformant Psn86-g and strain Psn86in the scenarios in which the cultivation time,pH,temperature,and suppression on C.destructans are restricted,it is found that compared with strain Psn86,mycelia growth and spores production of transformant Psn86-g are less than Psn86.However,the condition that is most suitable for growing both mycelia and spores is not changed and only the suppression rate decreases from 84%to 81.6%.4.Effects of biocontrol fungus T.harzianum Psn86 and organic fertilizer on the defense enzyme system of ginseng.Through the study on impacts of soil-fertilizer and soil-fertilizer with C.destructans,seven defensive enzymes and content of ASAFR and H₂O₂were detected.It is found that compared with the contrast group,soil-fertilizer and soil-fertilizer with C.destructans treatment can increase the activity of multiple defensive enzymes including oxidase（POD）,superoxide dismutase（SOD）,catalase（CAT）,phenylalanine ammonia-lyase（PAL）,and polyphenol oxidase（PPO）.The activity of defensive enzymes remains at a relatively high level,which can increase disease resistance of ginseng.From the above conclusion,it can be deduced that the main disease resistance mechanism by inducing the increase of activity of the defensive enzyme system.