The Study Of The Physiology And Biochemical Mechanism Of A New Ag-antibiotics702That Nduce Rice Defense Rhizoctonia Solani

Rice sheath blight is a major rice disease that often place major biological constraints on production. Compare with all the traditional disease-prevention methods, systemic acquired resistance (SAR) has many advantage, such as safety, broad spectrum disease control. It has been considered as a new way and a new technology to protect plant. The study of microbial secondary metabolites is a hot spot of researches on bio-prevention in recent years. Streptomyces702was screened from soil by Applied Microbiology Laboratory of Jiangxi Agricultural University. The antifungal compound extracting from the biological activity substance which produced by Streptomyces702is a polyene macrilide antibiotics, its purity achieved90%, named new agricultural antibiotics702. Through the further separation and purification the new agricultural antibiotics702by HPCL, we got monomer fraction DZP-9namely component2and DZP-8namely component3. Their purity respectivly achieved90.28%and99.47%. Evaluating through ultraviolet infraret、mass spectra and NMR, the result indicated that the molecular weight and molecular formula of DZP-9is C35H60O12and670Da and he molecular weight and molecular formula of DZP-8is C35H62O14and704Da. The component3is discovered and identified for the first time in the world.To test the prevention effect and the therapy effect of Rhizoctonia solani. We spray a series of concentrations (75μg/mL、100μg/mL、125μg/mL、150μg/mL、150μg/mL) of agricultural antibiotic702and the concentration of jinggangmycin is125μg/mL as comparison on the booting rice. The comparatively prevention effect and therapy effect respectively reached57%�'�10%. The result shows that it is better to spray the agricultural antibiotic702before diseasing and it reach the same effect as jinggangmycin.In order to explore the physiology and biochemical mechanism of the new ag-antibiotics702that induce rice defense Rhizoctonia solani, in this paper, we use Ag-antibiotic702as inducing factor and the rice as the object of experiment. We spray a series of concentrations (75ug/mL、100μg/mL、125μg/mL、150μg/mL、150ug/mL) of agricultural antibiotic702on the booting rice with four or five leaves, at the same time, we used the concentration of jinggangmycin is125μg/mL as positive comparison and water as negative comparison. After0,1,3,5,7,9days, we picked the rice leaves and extracted its five defense enzymes (SOD, POD, PPO, CAT, PAL) and two pathogeensis-related proteins (PRp)(chitinase andβ-1,3-glucanase) and determined their activities. We also extracted the ROS、MDA and total phenols in rice leaf and determined their contents. The main research results are as follows:The activities of the five defense enzymes and the two PR proteins in rice leaves after we spray a series of concentrations of agricultural antibiotic702and the125μg/mL jingangmycin were significantly higher than blank control. The of rice deal with the agricultural antibiotic702(125μg/mL) reached and exceed the treatment with125μg/mL jingangmycin. The results shows that the agricultural antibiotic702can enhance the activities of the five defense enzymes and the two PR proteins in rice leaf, initiator the defensive reaction of rice in order to keep a regularly physiology state.The contents of ROS in rice has a short and quick burst in the fist day, it always keeps in a low level. It was significantly lower than blank control. But the content of MDA was significantly higher than blank control. The results shows, in initial stage, the agricultural antibiotic702can induce the HR is an important mechanism to make the rice get SAR. In later stage, agricultural antibiotic702enhance the activity defense enzymes, the defense enzymes eliminate ROS, reduce the hurt of cell membrane from oxidation.The contents of total phenols in rice leaves after we spray a series of concentrations of agricultural antibiotic702and the125μg/mL jingangmycin were significantly higher than blank control. The of rice deal with the agricultural antibiotic702(125μg/mL) reached and exceed the treatment with125μg/mL jingangmycin. Through the synthetic analysis we have preliminarily studied the physiology and biochemical mechanism of a new polyene macrilide antibiotics-agricultural antibiotic702that induce rice defense Rhizoctonia solani. After the rice dealed with the new ag-antibiotics702, in initial stage, the agricultural antibiotic702can induce the HR is an important mechanism to make the rice get SAR. In later stage, agricultural antibiotic702enhance the activity defense enzymes, the defense enzymes eliminate ROS, reduce the hurt of cell membrane from oxidation. The result of this experiment is useful for the further research of disease prevent mechanism of agricultural antibiotic702.