Studies On Inhibitory Activity Of Resveratrol And Its Derivatives And Action Mechanism Of Resvrtatrol To Alternaria Solani

Due to the advantages of broad-spectrum, aboundresources, renewable and environmentally, botanical fungicide become a hot area of pesticide research. People have found many plant species with antibacterial or bactericidal activity, from which active substances separated involving pHenols, terpenes, flavonoids and other compounds. Stilbene compound is one of the botanical active ingredient with antibacterial activity and resveratrol is a typical representative of these compounds. Studies have shown that resveratrol has a wealth of biological activity and pharmacological effects, but relatively little research in agriculture. In order to clear the future of stilbene compounds in agricultural disease prevention and provide theoretical basis for in-depth study of these compounds, resveratrol was preferred as research object and cleared the virulence of pathogenic fungi tested in vitro and in vivo conditions, explored its mechanism of action and stability of the virulence, and determined joint virulence mixed with other fungicides. The main results are as follows:1. Results of the inhibitory spectrum of resveratrol and its analogues results:five tested compounds have a certain inhibitory effect on six pathogenic fungi of nine plant categories, including the highest activity of3,5-dihydroxy-4’-methoxy-stilbene (Ⅲ), which had the best inhibition on mycelial growth of tomato early blight with EC50up to3.31μg/mL, followed by apple mildew heart with EC5018.53μg/mL and Apple anthrax bacteria with EC5087.50μg/mL. Five compounds all showed high inhibitory activity on A. solani with EC50values between3.31～32.96μg/mL, and EC50values against B. cinerea between18.58～49.83μg/mL. The inhibitory activity on the rest of pathogenic fungi are different and no obvious rule.2. The effects of3,5-dihydroxy-4’-methoxy-stilbene on biological charcateristics against B.cinerea were tested. The highest inhibitory activity was on sporulation with67.96%inhibition rate at12.5μg/mL and nearly no sporulation at200μg/mL. EC50values of mycelial growth and spore germination were32.7070μg/mL and48.3867μg/mL. Sclerotia were the most tolerant vegetative part of the strain with sclerotia germination EC5077.2078μg/mL. There was no significant correlation between concentration and sclerotia quantity and weight.3. In vitro bioactivity of resveratrol against A. solani:iprodione showed the highest inhibitory activity on A. solani with EC501.1196μg/mL,40.5times higher than resvaratrol while the activity of carbendazim was the lowest with EC5051.4314μg/mL. Resveratrol performed fungistasis on mycelial growth, leading to hyphal abnormality, while the inhibition of100μg/mL was65.0%with EC5051.4314μg/mL. The EC50of resveratrol on spore germination was113.7339μg/mL and inhibition at200μg/mL was69.70%. The activity of mancozeb on spore germination was far higher than resveratrol, with86.59%inhibition rate at0.5μg/mL. Both resveratrol and mancozeb had no effect on spore morphology.4. Determination of activity of resveratrol in vivo:leaf method inoculanted with hyphal disc and pot-culture method inoculant with spores were used to test the bioactivity of resveratrol in vivo. In the case of resveratrol used befor inoculation, spot diameter on leaf or disease index was decreased with the increase of resveratrol. Control effects of resveratrol at0～1000μg/mL was between8.14～60.31%, with EC50661.7178μg/mL in leaf method, while control effect was15.33%at100μg/mL and54.56%at5000μg/mL in pot-culture method, of which the concentration was setted between0～5000μg/mL, so there was a conclusion that the control effect got by leaf method was higher than that of pot-culture method. Control effects were not ideal in the event of inoculation followed by resveratrol.5. The effects of resveratrol on cell membrane permeability, contents of soluble protein and DNA of A. solani were determined. Results showed that:conductivities of all treatments including control increased over processing time, and resveratrol could add the permeability of mycelia, resulting in electrolyte leakage and electrical conductivity increased by218.2%after treated180min at200μg/mL. After7days, compared with control soulbe protein contents of hypha treated by resveratrol declined. As the concentration increases, the protein content decreased. The protein content was0.709mg/g at100μg/mL with inhibitory rate70.00%, but resveratrol failed to inhibit DNA synthesis in the dose range.6. pH value and UV rays can affect the activity of resveratrol. Resvaratrol behaved the most notable inhibitory action on mycelial growth and spore germination at pH value6, at the moment fresh weight inhibition rate was12.01%, dry weight inhibition rate was30.42%at20μg/mL, and spore germination inhibition rate was3.24%at50μg/mL. Colony diameter enlarged as the irradiation time increased. As time increase from0.5to4h, the colony diameter increased from2.60cm to3.40cm.Temperature can cause faint degration of resveratrol, afer stocked in dark places for8days, degradation rates of4℃、25℃、35℃was1.43%、2.05%、5.60%separately.7. There was a certain synergism of resveratrol mixed with mancozeb and iprodione separately, but antagonism with carbendazim and chlorothalonil. Among them, the mixture of resveratrol and mancozeb had the most significantly synergism with proportioning ratio of7:1was the best proportion showing additive effect with EC50value2.2790μg/mL and CTC863.93, while1:7was the worst propotion with EC50value21.2359μg/mL and CTC172.34. There were weak synergistic effects of iprodione mixtured with resveratrol at1:7and7:1, with EC50value5.6331μg/mL、1.0194μg/mL and CTC134.35、125.05, while remaining ratio showed antagonism with CTC less than120.