| Botrytis cinerea was used in the test to observe the ash of mycelial growth and spore germination treated with cinnamaldehyde in vitro and explored its antibacterial mechanism in a preliminary by measuring the cell membrane permeability of Botrytis cinerea and soluble sugar and soluble protein contents of hyphae leaching solution after the treatment with cinnamaldehyde. To explore the effect of cinnamaldehyde on the control of tomato fruits gray mold and the mechanism of induced disease resistance, the experiment investigated the incidence of tomato fruits which were dipped in the cinnamaldehyde after inoculated with Botrytis cinerea and enzyme activity and contents of materials that were related with disease resistance. Infection situation of tomato fruits which were dipped in cinnamaldehyde solution and its physiological nutritional quality changes during the storage were studied. The results are as follows:1. Used Botrytis cinerea as the research objective, spore coating experiment was carried out under the poisoned medium with the preperation of10μg/mL,20μg/mL,40μg/mL and60μg/mL of cinnamaldehyde. We found that cinnamaldehyde had a good inhibition effect on spore germination of Botrytis cinerea. Concentration of cinnamaldehyde had significantly negative correlation with spore germination rate, and the EC50value is31.956μg/mL. The higher is the concentration, the better is spore germination inhibition effect. The spore germination rate reached100%in the concentration of60μg/mL. Under the microscope we found that germ tubes of Botrytis cinerea which were treated with cinnamaldehyde were tubby or there were no germ tubes and the wall was rough and the germination was delayed, while spore germinate rapid and the germ tubes was slender and bud wall was smooth in the control. The effective antibacterial concentration of cinnamaldehyde to mycelial was95.596μg/mL in the culture of poisoned medium with the concentration of50,100,150,200μg/mL in vitro. The higher is cinnamaldehyde concentration, the better effect on the inhibition of colony diameter expansion, and the growth of hypha was completely inhibited in the concentration of200μg/mL. After the observation of colony morphology of Botrytis cinerea, we found that mycelia treated with high concentration of cinamaldehyde were more rare and the pigment was deeper than the control. Mycelium surface were rougher than the control under the microscope. The content of the cell aggregated as the result of the leakage of protoplast and turned black. After the shake cultivation of hypha in the concentrations of50,100,150,200 μg/mL, we found that the cell membrane permeability was the highest of all the concentrations. It reached61%in200μg/mL while the control group was only14%at160min. Soluble sugar and soluble protein contents of hyphae leaching solution were higher than that of control group (P<0.05). It suggested that cinnamaldehyde damaged the cell membrane and formal permeability, as a result of the leakage of cell contents and intracellular metabolic disorder. The growth of mycelium was inhibited finally. Test for bacteriostatic mechanism showed that cinamaldehyde can increase cell membrane permeability, therefore making soluble sugar and soluble protein leak out of the cell, with the result that electrolyte both inside and outside the cell imbalanced and growth of mycelium inhibited.2. Cinnamaldehyde could suppress disease spot diameter and reduce the incidence of tomato fruits that were inoculated with Botrytis cinerea.Tomato friuts in control and1000μg/mL all attacked disease at the5th day, while the incidence of2000μg/mL and4000μg/mL were32.1%and11.3%. Tomato fruits were interval damage inoculated in24,48,72,96and120h after treated with4000μg/mL cinnamaldehyde. We discovered that the disease spot diameter in the96th h was the smallest which confirmed that cinnamaldehyde can induce disease resistance of tomato fruits and the sustained time was96h. Enzyme activty as POD, PPO, PAL and contents of total phenolic and flavonoids in tomato fruits which were treated with stabbed, stabbed and inoculation, stabbed-inoculation and cinnamaldehyde were tested. The results showed that cinnamaldehyde group had highest enzymes activity of all. The activity was2.40U/g FW,2.69U/g FW and4.25U/g FW during the peak, while the control group were0.82U/g FW,1.76U/g FW and3.09U/g FW. The conclusion was that cinnamaldehyde could improve enzymes activity that were related with disease resistance and contents of disease-resistant materials such as total polyphenols and flavonoids, therefore improved gray mold resistance of tomato fruits.3. The experiment explored disease incidence and the change of physiological and biochemical quality of tomato fruits treated with cinnamaldehyde during the storage. It showed that cinnamaldehyde can inhibit the incidence and reduce the disease index of tomato fruits during the storage. Incidence of tomato fruits dealed with cinnamaldehyde in concentration of4000μg/mL,2000μg/mL and1000μg/mL were respectively8.3%,30.7%and89.3%, while the control group was100%; disease index were respectively14,26and33, whlie the control group was56. Treatment with the concentration of4000μg/mL could significantly inhibit the weightlessness of tomato fruits. The weightlessness rate was only0.5%at15th day, while the control group was4%; the hardness was4.3times higher than the control; soluble solids, titratable acids and vitamin C were respectively1.7times,2.6times and1.9times higher than the control. As a consequence, concentration of4000μg/mL was the best to maintain physical quality of tomato fruits during the storage. It can achieve its nutritional value and commodity value as much as possible. |
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