Research On The Symbiotic Relationship Between Trichoderma And Rice

The plants-microbiology system combining with plants and soil microorganisms is possessed of many functions, such as exchanging metabolic product, activing plant defense behaviour, and the effect of plants growth. The Trichoderma mutant TUV-13 was obtained by means of the UV-induced in this paper to study the interaction with rice. The strain TUV-13 was labeled of myclobutanil and from the origin of strain T_2-16 with the strongest antagonistic activity to fungus pathogens in our lab. The comprison on the the culture traits, ethyl acetate extract composition and content, colonization capacity in the rice plant, genetic stability, and other biological characteristics between TUV-13 and T_2-16, has proved that TUV-13 is a clear genetic markers of anti-double-mutant Trichoderma Strain, which can be used as research marked strain to study the symbiotic relationship with rice under open field conditions. In addition, the biocontrol agent of TUV-13 mutant and the original strain were subjected to a random amplified polymorphic DNAs (RAPD) study. Furthermore, based on NTSYS cluster analysis, the results showed that the inheritable character of induced mutant TUV-13 was stable. The DNA homology between TUV-13 mutant and the original strain shows significance of difference.Then the colonization trends of stain TUV-13 in rice was analyzed in the field test.The results showed that TUV-13 could be subsist and develop in tissues by presoaking the seeds with TUV-13 fermented production.The symbiotic relation between the Trichoderma mutant TUV-13 and rice could establish. The establishment and dynamic ecology of the symbiont studied through the surveying the growth rates and the resistance under two different cultivated varieties and different cultivated type in past two years. The results showed that soaking, through the inoculation method Trichoderma can colonize in the surface of rice organs and the cortex gap in cells, as the growth and development of rice. Proliferation in the seedlings period, but with the further development of the growth of rice plants, the number of the colonization of Trichoderma is less and less, to the reproductive phase of growth, the number of Trichoderma sharply reduced. The symbiotic relationship between Trichoderma with Rice body can induce the defensive enzyme activities of peroxidase(POD), polyphenol oxidase (PPO) and phenylalanine ammonia-lyase(PAL) in rice seedling were increased by various level, enhancing resistance to its main rice disease. The most obvious is to enhance the quality of rice seedlings to promote the tiller heading, eventually improve rice production. In addition, the investigation of the seedlings in the field on chilling injury and the occurrence and development of rice sheath blight show that Trichoderma-symbiotic relationship can enhance the ability of cold resistance, control of rice sheath blight.Further, the best way to establish the symbiotic was studied. The spore suspension of TUV-13 was applied in rice by soaking, pruned-root dip and inoculations of daubing leave. The results indicated that each method could led to colonization of TUV-13 strain in rice tissues, and among them, the soaking is the most effective way to establishing symbiotic relationship between Trichoderma strain and rice. Because the TUV-13 strain could systematic distribution in rice when it used by soaking, and the others inocula-tions methods could only be the local symbiotic relationship between the rice body and Trichoderma.The mechanism of the symbiotic formation also obtains. Trichoderma strains could be absorbed on the surface of rice chaff when the rice seeds soaked with the spore suspension of Trichoderma.Follow seed germining, Trichoderma spore began to germinate and form primary germtube.Then the appressoria began to form at the tips of germtube and attached on the surface of host. Further, it coule be microscopically observed the hyphae and conidiophores to existdetween mesophyllic cells. And the target strain TUV-13 could to internal stem ,leaf and root stably .It was confirmed that the strain was endophytes in rice and could develop, transfer in rice. Observation to the macroscopical and microscopical process indicated that the rice and Trichoderma strain were compatible.The temperature, soaking time could affect the colonization of Trichoderma in the rice plants. The symbiont of Trichoderma and rice existed exchange of the free amino acids. Meanwhile, the symbiont were induced resistance to the sheath blight.The test results of Solvent Extraction System showed that chloroform is the most solvent for Trichoderma TUV-13 anti-bacterial substance extracted from culture in rice vitro. GC-MS detected TUV-13 chloroform extract included more than 40 kinds of chemical substances, of which number of alkanes,13 kinds, is the largest.The others contains organic acids, esters, ketones, steroids, and other types of organic compounds. The comprison on macroporous resin HP-20 and silica gel column chromatography, which the outcome of the trial of oil ethyl ether-eluting agent for the silica gel column chromatography system was Trichoderma TUV-13 anti-bacterial substances, determined that the optimum separation methods are effectiveto isolate the 3 different structure of anti-bacterial substance. Sub flow 2, the strongest anti-bacterial activity, identified as 18 carbon methyl diene, Sub flow 9, followed by sub-stream, identified as steroid antibiotics. Indoor cells in vitro Toxicity show Trichoderma TUV-13 metabolites of 18-carbon diene methyl inhibiting effect of different pathogens have significant differences, of which rice sheath blight was the most sensitive, its EC₅₀ was 9.27μg/mL; to peanuts southern blight EC50 value was 21.53μg/mL; to phytophthora EC50 was 131.48μg/mL; torice blast EC₅₀ was 428μg/mL. At the same time, the seeds vigor of different rice varieties were improved by the substance.