Analysis On The Diversity Of Soil Microorganism In The Rhizosphere Of Different Allelopathic Potential Rice Accessions Under Different Nitrogen Supplies

As one of the most important chemoecological phenomenon, allelopathy refers to the favorable or deleterious effects of one plant on its neighboring plants (including microbes) through the release of secondary metabolism chemical compounds into the environment via volatilization, leaching, excretion, and decomposition. Using rice allelopathy to control weeds in agroecological system has been one of the hottest researching fields, which will be a key technology to control weed safely and friendly in 21^st century.As we all know, soil habitates is the one of the main agents where the allelopathic activity is occurred. The microbes engage in the transformation of organic matters in soil enviorment, and the interactions result in the features of the allelochemicals such the state, the activity, the utilize and even the potential of the allelopathy by degrade or transformation. However, it has proven difficult to estimate biological diversity in soils because most of the available methods are dependent on cultivation of organisms under laboratory conditions. So the molecular technologies T-RFLP and soil proteomics are employed to explore the microbe diversity of rice rhizosphere.As we well know, the micro-ecology environment and functional groups of soil microbials will vary according to the quantity and categories of exudates from plants. It is obvious that the increased phenolic acids synthesised and secreted by allelopathic rice in N deficiency can influence the structure of soil microbials because of the chemotaxis of microbial. Thereby, the author studied the structure difference of soil microbial in allelopathic and non-allelopathy rice aceessions under normal and low N levels, and planed to obtain some knowledge about chemotaxis of soil microbial induced by phenolic acids. The results showed that there were only sixteen differental T-RFs caused by diffenent rice accessions in all of the detected 175 T-RFs, which suggested the main.difference in vertical distribution and horizontal distribution of microbial was induced by N effect. On the whole, the microbial is most rich in low nitrogen supply. And at the same nitrogen supply, the diversity of microbial in rhizosphere of allelopathic rice is greater than that in non-allelopathic rice rhizosphere. The quantity of microbial in the rhizosphere of allelopathic rice is more than that in 0-5cm layer, and the quantity of microbial in non-allelopathic rice and allelopathic rice in normal N supply was on the contrary, that is to say, the quantity of microbial in 0-5cm layer was more than that in the rhizosphere. And the microbial in 0-5cm layer and 5-20cm layer was richer than that in other samples. The different microbial caused by N nutrient was comprised of N cycle related, acids production and eosinophilic microbials related such as propionibacterium and acidithiobacillus,and clostridium related which can produce exotoxin, spirochaeta related which can transduct and defense, and some pathogens such as mycoplasma, phytoplasma and klebsiella, which is correlated to the more C source and corresponding micro-ecology environment provided by phenolic acids in the secretion of allelopathic rice under N deficiency.The soil proteomics is preliminarily established in the paper. The same as the soil genomics, soil proteomics can display the most of microbes. However, the traditional methods only can culture the 0.1%-1% of the total microbes. Of course, the difference is in soil genomics and proteomics, the proteomics is a direct approach to reveal the functional microbes or proteins. The rate of soil microbe extraction is 37.5% in the study.In a word, T-RFLP is used to analysis the diversity of rhizosphere microbials in rice, and at the same time the technology of soil proteomics is premiliary established, which is few studied, the existing reports have defects in repeating. The combined approach of molecular technologies used for present studies was only to effectively control the "false positive" caused by single molecular technology. The technology of soil proteomics is further improved. The study will conquer a solid foundation for detection and identification of the allelopathic microbe as an indicator.