Effect Of Photosynthetic Bacteria PSB06 On Rice Growth And Antagonism Of Exogenous Protein To Magnaporthe Grisea

Rice blast is one of the devastating diseases that affect the sustainable development of the rice industry and poses an important threat to global food production.At present,the prevention and control of rice blast mainly relies on disease-resistant varieties and chemical pesticides.Because the breeding time of disease-resistant varieties is longer,the physiological races of rice blast fungus can easily mutate and make the resistant varieties lose drug resistance,and overuse of chemical pesticides leads to pathogenic bacteria.The significant increase in drug resistance has caused serious pollution to the environment and ecology.Therefore,the search for effective ways for biological control of rice blast is crucial for ensuring food security.Photosynthetic bacteria are a class of prokaryotic microorganisms with a light energy synthesis system.They have high nutritional value and are widely used in agriculture.In this thesis,the photosynthetic bacteria PSB06 was used to promote the growth of rice and the inhibition of extracellular proteins against rice blast fungus was found:1.Photosynthetic bacteria have good effect of preventing diseases and promoting growth.In this experiment,it was found that photosynthetic bacterial strains of Rhodopseudomonas palustris PSB06 inoculated seeds of rice could increase the seed germination rate.Compared with the control,the germination seed buds were longer.Root length was increased by 250% and 249%,respectively.At the same time,photosynthetic bacteria also promoted seedling growth.Rice stalks were 36% higher than the control,leaf chlorophyll a and b content were increased by 27.5% and 18%,respectively;in drought stress.Under the photosynthetic bacteria,SOD and POD values of rice seedlings soaked at the seedling stage were increased by 72% and38.5%,respectively,and were more effective in maintaining free radicals balance in plants.2.The experiment of extracting photosynthetic bacteria PSB06 extracellular protein was carried out in the antibacterial experiment.The results showed that extracellular proteins could significantly inhibit the growth of rice blast fungus.The growth rate of rice blast fungus after treatment with 200ug/ml total protein concentration was significantly lower than that of the control group.After 3 days of inoculation and culture at 28 °C,the inhibition rate reached 50%.The germination rate of the 200 ?g/mL protein-treated rice blast pathogen was reduced by 43.5%,andthe appressorium formation rate decreased by 65% ??after 8 hours of culture.The5-fold dilution was 40 ?g/ml.After treatment with ml protein concentration,the germination rate of rice blast was reduced by 21%,the formation rate of appressorium was reduced by 30% after 8 hours of culture,the germination rate of 10 times protein concentration diluted by 20 ?g/mL of rice blast decreased by 7.6%,and the appressor cells were cultured for 8 hours.The formation rate decreased by 5%.At the same time,the results of rice leaf infestation experiments showed that the extracellular protein of photosynthetic bacteria PSB06 could significantly inhibit the pathogenicity of rice blast fungus,and the number of lesions was counted after 7 days.It was found that when the concentration of spraying protein at the leaves was 200 ?g/mL,the number of lesions decreased 82 %.Further,the extracellular proteins of photosynthetic bacteria were purified by molecular sieve to obtain the No.4 protein component.The No.4 component was purified through an anion column to obtain the limited component 4-2.After purification,the concentration was 10 ?g/mL of photosynthetic bacteria.Protein 4-2 protein treatment after 4h inhibition of rice blast spores germination rate was 30%,8 hours after the inhibition of appressorium mycelia formation was 25.3%.The 4-2 component was identified by the protein profile as 5proteins.In summary,photosynthetic bacteria have good disease-preventive effects.Photosynthetic bacteria can not only effectively promote the growth of rice,but also their extracellular proteins can effectively inhibit the growth of the rice blast fungus,appressorium formation,and infection of the host.The research is expected to provide a theoretical basis for the application and promotion of photosynthetic bacteria in the prevention and control of rice blast,and provide technical support for the reduction of chemical pesticides and the improvement of farmland ecological environment.