| Citrus is an important economy crop in China,which is widely planted in China,and the good and sustainable development of the citrus industry is of great significance.However,China’s citrus cultivation is facing a variety of diseases such as citrus yellow huanglongbing,and it is particularly important to find safe and reliable control methods to control yellow dragon disease.In this experiment,Bacillus polyviscous and 12 compounds were selected to treat citrus plants with Huanglong’s disease by root irrigation and foliar spraying,and combined with real-time fluorescent PCR and conventional PCR methods,HLB was detected on the materials before and after reagent treatment,and the physiological and biochemical indexes and resistance-related substances of plants were detected,so as to evaluate the control effect of polyslime molds and small molecule compounds on Huanglongbing.The specific results of the study are as follows:1.Effect of Bacillus polymyxoidus in controlling citrus Huanglongbing.The concentration of pathogenic bacteria in Huanglongbing was reduced after the treatment of citrus seedlings infected with Huanglongbing,including 3 different varieties,and the mixed treatment of polymyxobacteria and probiotic protein strengthened the control effect of pathogenic bacteria,and the treatment effect of live bacteria was slightly better than that of inactivated polymyxobacteria.Although the plant height,stem and crown width were increased after polymyxilla treatment,the difference was not significant.The treatment increased the chlorophyll content and leaf net photosynthetic rate,thereby promoting plant growth.The determination of starch content showed that the treatment could significantly reduce the accumulation of starch content in the leaves of susceptible plants,which was conducive to the transportation of substances in citrus plants,and the reduction effect of mixed treatment was better than that of fungi alone.Microbial community analysis showed that the OTU value and Shannon index increased after polyslime treatment,indicating that polyslime bacteria treatment may interact with soil microorganisms and increase soil microbial abundance,but the microbial diversity decreased to a certain extent.2.Small molecule compounds control the effect of citrus Huanglongbing and its effect on physiological and biochemical indexes.q PCR molecular detection of phloem pathogens on citrus leaf veins before and after treatment of small molecule compounds,and it was found that the concentration of pathogenic bacteria could be reduced to varying degrees after treatment of small molecule compounds.The results showed that ethionamide and paminosalicylic acid were the most effective in inhibiting pathogen concentration,and the pathogen detection rate after treatment was 25%.The chlorophyll,lignin and starch contents of the test materials treated with different small molecules were analyzed,and the results showed that the chlorophyll content and lignin content of plant leaves after the treatment of small molecule TMC207,small molecule PA-824 and small molecule de la Mani were increased,and the growth promotion effect was remarkable.After the treatment of tetraethylthiuram disulfide,ethambutol hydrochloride and 2-bromo-2-nitro-1,3-propanediol,the lignin activity of plants was significantly increased,and the starch content was reduced,which was conducive to the resistance to Huanglongbing.The polyphenol oxidase,calloin content and reactive oxygen species content of the treated test materials were analyzed,and it was found that the content of polyphenol oxidase increased significantly after the treatment of small molecules PA-824,deramanidine and the compound ethambutol hydrochloride and pyrazinamide,and the treatment of the compound ethylthioisoamide reduced the level of calloin and reactive oxygen species,and increased the activity of polyphenol oxidase.Based on the effects of changes in pathogen concentration and physiological and biochemical indexes of Huanglongbing,the small molecule PA-824 and the compound ethylthiaoamide had good effects on inhibiting pathogen concentration and enhancing plant resistance. |
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