| Tobacco is an important economic crop in China, but the continuous cropping makes the monoculture quality and yield lower, which limits the development of our country’s economy. In this study, we analyzed the endophytic prokaryotic community of few tobacco intercropped with different aromatic plants at a vigorous growing period like stable, growing period and late picking period, which helped us to explore potential applications of microbial resources and new species resources.We studied the endophyte prokaryotic community of different intercropped types based on culture-dependent and uncultured-independent methods. First, we have detected the utilization of31kinds of carbon source by using Biolog ECO plates for five different intercropped plants, for which we estimated the metabolic functional diversity and the results showed that the intercropping enhanced the diversity of metabolic functions. The diversity of microbial diversity was highest at stable period, except with Pelargonium roseum. However, results also showed that, intercropped with sweet basil was good for tobacco just for one year planting because of its highest diversity of metabolic functional at both vigorous and stable growing periods. The diversity of metabolic functions was rich when intercropped with mature Pelargonium roseum. Further, intercropping with Mentha haplocalyx Brig was also very rich at late picking period, which is good for overcoming the barriers of continuous cropping.On the basis of the utilization of31kinds of carbon source, we designed some isolation media for culturable prokaryotes. We isolated1,032strains from the soil samples of the five different intercropped types at their fast growing period. The isolated strains belonged to76genera and205species. We got1,230strains at the stable growing period and368strains at late picking period, which belongs to82genera and219species,43genera and89species, respectively. Among of these strains, Saccharomonospora, Castellaniella, Kribbella, Nonomuraea, Actinopolymorpha, Bosea, Saccharothrix, Streptosporangium, Tsukamurella, Promicromonospora, Sphingopyxis, Actinomadura, Lentzea, Microlunatus, Sphingomonas, Hymenobacter, Aeromicrobium, Pseudonocardia were first isolated from tobacco plant.We calculated the Shannon Index of all samples of different periods. We found the stable growing period has a higher number of Shannon Index.The results showed that the tobacco can change the distribution of microbial flora of the soil. Different intercropping types had the different microbial diversity when compared with the control. In this study, our isolation media and methods were good for the isolation of microbes at the intercropping sites because of shannon index was higher at each site. The microbe diversity was highest at the stable growing period than the vigorous growing period when the tobacco sites were intercropped with rosemary, cymbopogon and Pelargonium roseum respectively.In our study, we selected rhizosphere soil and used high-throughput sequencing method for isolation of microbes for different types of plants. The result indicates that the predominant bacteria group was the Proteobacteria, which correlates with the other environments. The Proteobacteria was the largest bacteria group. In tobacco rhizosphere, the Proteobacteria accounts for approximately50%of all bacteria. In control group "GCKY" the Proteobacteria accounts50.8%. In GDY and GCY there are obvious changes, the Proteobacteria accounts37.7%and44.5%, respectively, but in GAY the Protobacteria accounts for59.9%. The second largest group was Actinobacteria and took smaller part of the bacteria mass in rhizosphere than the control group; the smallest group was GBY,14.4%. The third group belongs to the domain Bacteria, but they could not be assigned to any known phylum, and the proportion was also relatively high, with an average of14.2%. The control group was11.9%, GAY was9.9%, lower than the control group, and others were higher than the control group, in which, the highest was GDY, up to21%. The proportion of these microorganisms in the rhizosphere soil of tobacco was high, therefore, to understand the role of these organisms in this microenvironment, we also need to use the means of pure culture method to isolate as many microorganisms which belongs to this group as possible, and use a variety of physiological and biochemical experiments. Another group was Bacteroidetes, the average percentage was5.2, whereas the control group was4.6%. Among them the GAY was the lowest,2.0%, in contrast GDY and GCY were the highest,6.9%and6.7%. Further, Firmicutes accounts for2.4%, Gemmatimonadetes accounts for2.3%, Chloroflexi accounts for1.8%, Verrucomicrobia accounts for0.8%, Unclassified unit TM7accounts for0.9%, Nitrospira accounts for0.5%, the control group was0.3%, GAY was2%, GDY, GDY were0.4%, GCY and GEY was1.0%,0.7%. Shannon index calculation results were:GAY7.872, GAY9.405, GAY9.324, GDY10.779, GEY9.102, GCKY9.117. Tobacco intercropping patterns with Rosemary and lemongrass showed highest index of microbial diversity.We got704strains from the five different intercropping types at a stable, growing period, which included136species of65genera. There were266strains isolated from the tobacco, which distributed in96species of40genera. Among of these strains, Tsukamurella, Sphingobacterium, Microbacterium, Brevibacterium, Achromobacter, Brevibacillus, Sphingopyxis, Micrococcus, Ensifer, Rhodococcus, Ochrobactrum, Advenella, Curtobacterium, Nocardiopsis, Rothia, Sphingomonas, Microcella, Brevundimonas, Methylobacterium, Variovorax, Leucobacter, Devosia, Kocuria, Brachybacterium, Pseudonocardia, Nocardioictes, Nesterenkonia,Aetinokineospora, Agrococcus and another three new genus were first isolated from tobacco plant.We selected strains to do some further experiments, such as degradation of phosphorus, nicotine utilization, nitrogen fixation, Cr6+tolerance, siderophores production and amylase, found that there are a lot of strains have important ability in agriculture application.Phytoedaphon is beneficial to plants and increase the soil fertility because it can degrade the pesticide residue. Not only it can enhance the adverse resistance of plant, but it also can provide nutrients for the plants. In this study, we used the K326tobacco as the research object in the Hills impression of stone forest, in Kunming, Yunnan, southwest China, to study the trends of phytoedaphon, among five different intercropping types. Through this study, changes in tobacco rhizosphere microbial communities provide a theoretical basis and technical support for the selection of suitable intercropping model and for selecting the appropriate type for intercropping, improving yield and quality of tobacco. We isolated a large number of microbial resources from the rhizosphere soil and plant, by testing enzyme activities of isolates; we selected a group of bacteria that may have potential application on tobacco cultivation and processing. According to this study, we not only provided a rich source for further bacteria strains filtering and also restored a number of bacteria strain resources for follow-up agricultural and industrial production. |
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