Study On The Resistance Induced By Several Chemicals Against Powdery Mildew In Tomato

Tomato powdery mildew is the main fungal diseases in vegetable production,perennial in high temperature season,90%of plants get this disease and30%of production lost every year.With the expansion of production scale of tomato, effective prevention of tomato powdery mildew, improve tomato production, reduce the economic loss is more important. Pesticides is the main prevention in the yield production.The use of pesticides makes pathogen and pest get a resistance to couter it.Environment suffered,and beneficial organisms harmed,what’s worse,pesticides may cause poisonous vegetables which is very harmful for human body.Chemical control has a quickly effect, convenient usage and other advantages, become the most effective way in the prevention and control of vegetable pest.In this experiment, four kinds of chemical reagents were tested. DL-β-amino-n-butyric acid, BABA,Benzothiadiazole, BTH Chitosan, CTS and K2SIO3.to induced resistance of tomato to Powdery Mildew,And preliminary studied mechanism of induced resistance. And the results are shown below:1Tomato powdery mildew was developed in a lighted incubator at Northeast Agricultural University and operated morphological and molecular identification and analysis,Lately,the powdery mildew was identified as Oidium neolycopersici L. Kiss.According to the fungal detection of rDNA-ITS sequence analysis showed the pathogen and new tomato Oidium O.neolycopersici homology is100%. By constructing phylogenetic tree we found that the powdery mildew tested on this experiment is different from those in other region and countries. We deduced that this is due to the evolution at Harbin area.2Four kinds of inducing reagent BABA,BTH,CTS and K2SIO3were all have the ability to induced tomato have a powdery mildew resistance effect.Reduced the disease index at a72.77%.There isn’t much different between the four inducing reagent.BABA、BTH were the best,The best concentration induced respectively were500mg/L and50mg/L3There are regular intervals from the formation of induced plant resistance Best interval day for BABA is two days,the duration of induce tomato powdery mildew can up to10days.The same data for BTH is three and seven days.There is significant effect of inducing agents on different growth period of tomato powdery mildew resistance.Three different growth stages on tomato was induced after treatment for induction strength, Comparison of the effect:The2leaf stage>6leaf stage>8leaf stage.The relationship between different growing stage and plant induced resistance effect is very important for protecting the plants. 4Using500mg/L BABA and50mg/1BTH for induction and inoculation of susceptible tomato, result is significant improved in POD, PPO, CAT activity, suggest that there are physiological changes after the induction.5This search reveals that infected leaves included by BABA and BTH.thereby infected leaves generate messenger molecule-H2O2and NO, the content of H2O2in the included group is higher than the control group clearly. H2O2and NO messenger molecule participate in the resistance signal transduction with plant disease, and closely related to the plant disease responding.6BABA and BTH can stimulate the expression of some resistant genes.Protein genes CHI3、 GLUCA、GLBCB and PR1A related to the disease in tomato leaves have different expression level.What’s unchanged is the susceptible varieties of expression is higher than that of resistant varieties of expression.Mechanism of BABA and BTH can induced tomato resistent to Powdery mildew probably is:In the interaction process of tomato powdery mildew, BABA and BTH are involved in the physiological metabolism of tomato, stimulate the resistance related gene,induced systemic acquired resistance (SAR), thereby inhibiting the harm of powdery mildew on tomato.