| Rice is the main food crop in China,so a large number of scholars had studied the growth process of rice in order to achieve stable and high yield of rice.During the growth of rice,it can assemble its own unique root microbial community.Some microorganisms play an important role in rice growth,and some microorganisms are harmful to rice growth.Rice-microbe interactions involve a variety of signal transmissions.As one of the special signal substances,volatile organic compounds(VOCs)have the characteristics of small molecular weight,low boiling point,weak polarity,lipophilicity,etc.,which can mediate the Non-contact interaction between organisms and a very small amount of VOCs can exert significant effect,play an important role in the long-distance rhizosphere signal transmission,have broad agricultural application prospects.This subject used traditional culture methods,new culture strategies,high-throughput culture methods and 12 kinds of culture media to comprehensively isolate and culture rice zone bacteria.The headspace solid-phase microextraction combined and gas chromatography-mass spectrometry was used to analyze and compare the mVOCs.The composition of volatile organic compounds released from rice zone bacteria was tested by using a double Petri dish assay to detect the inhibitory effect of these bacteria on pathogenic bacteria.Finally,statistical analysis was used to find potential volatile organic compounds with antibacterial activity.The findings are as follows:1.The roots of potted rice in the greenhouse as samples,through 12 kinds of culture media(beef peptone,Gaoshi No.1,ten-fold diluted beef peptone,ten-fold diluted Gaoshi No.1,TSB,TYG,YEM,M408,M715,Flour,TWYE and soil extract medium),three kinds of culture methods(traditional culture method,new culture strategy and high-throughput culture method)to comprehensively isolate the rice zone bacteria,and obtained 2033 strains of rice zone bacteria,these bacteria belong to Actinobacteria,Bacteroidetes,Firmicutes and Proteobacteria.2.Rice zone bacteria can release a variety of volatile organic compounds,and some volatile organic compounds had a significant inhibitory effect on rice pathogens.Correlation analysis and in vitro validation identified two new antimicriobial substances(5-methyl-2-hexanone and 3-methylbutanoic acid)and one substance with potential antimicriobial substances(5-methyl-3-hexanone).All these substances and strains have the potential as biological resources of new drugs and antifungal metabolites.3.By detecting the VOCs of 98 different bacteria in the rice zone,it was found that 28 types of substances were released from the rice zone bacteria,and there were huge differences between different genera.VOCs released by all strains of Bacillus and Streptomyces can inhibit the growth of Fusarium graminearum.Bacillus releases 25 types(146 species).Ketones are the most,40 species,alcohols substances were followed by 21 species.Streptomyces released a total of 16 substances.Correlation analysis revealed that the amount of VOCs released and the number of species had no correlation with the bacteriostatic rate.The substance 13-methyltetradecanoate may have Potential antibacterial activity.In general,rice zone culturable bacteria are mainly Actinobacteria,Bacteroidetes,Firmicutes and Proteobacteria.Using TSB,TYG,YEM,M408,M715,Flour,TWYE and soil extract medium can significantly improve rice zone culturability.High-throughput culture method can cultivate 20.4% of rice zone bacteria.Rice zone bacteria can release a variety of volatile organic compounds,and some volatile organic compounds have a significant inhibitory effect on rice pathogenic bacteria.These strains and volatile organic compounds have the potential to be used as new pesticide and resources of antifungal metabolites.However,due to the large number of rice zone bacteria,the types of VOCs released by the rice zones are more abundant and complex.There is still a huge potential for VOCs released by rice zone bacteria. |
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