Expression Of Trichothecium Roseum Chitinase Trchi1Gene And Thermostable Mnsod Gene In Rice Enhances Resistance

Chitinase is generally considered to be an enzyme related to fungi disease resistance. Chitinases produced by mycoparasites can degrade the cell wall of pathogenic fungal hosts, suppress mycelium growth, spore germination and germ tube elongation. Transgenic crops encoding mycoparasitic chintinase gene have high disease resistance with broad spectrum and long persistence and their insect resistance could also be enhanced. The superoxide dismutases are metallo-enzymes that catalyze the dismutation of superoxide(O2’-) to hydrogen peroxide(H202) and molecular oxygen(O2). It can make biological defense oxidative damage. Exposure of plants to environmental stresses, including salinity, drought, cold and high temperatures, can produce large amount of reactive oxygen species (ROS). R.OS can damage intracellular macromolecules, generate lesions in DNA, cause membrane damage, and affect protein synthesis and stability, ultimately affect plant growth and development. SOD can reduce the stress on the plant cell damage by scavenging reactive oxygen species within the cell, which can reduce the accumulation of intracellular reactive oxygen species, reduce harmness of adversity. It plays an important role in enhancing the resilience of plants to salts, etc.Trichothecium roseum is an important mycoparasites. It can effectively inhibit the expansion and hazards of various plant pathogenic fungi. Extracellular chitinase produced by Trichothecium roseum involved in the process of hyperparasitism and resistance. Thermomyces lanuginosus and Thermoascus aurantiacus var.levisporus are widely distributed soil-inhibiting fungi of considerable interest producers of thermostable enzymes, including glucoamylase, cellulase, endocellulase, xylanase, and laccase. The fungi have great value in research and application.The chitinase gene trchil from Trichothecium roseum, zjmnsod gene from Thermomyces lanuginosus and esjmnsod gene from Thermoascus aurantiacus var. levisporus were cloned by specific amplification.To investigate the function of trchil, zjmnsod and esjmnsod, the expression vectors were constructed by pCAMBIA1300of the Maize Ubiquitin promoter with three genes, then transformed into rice by Agrobacterium-mediated transformation method. The results showed that trchil, zjmnsod and esjmnsod, was integrated into the rice genome by PCR and RT-PCR detection, and expressed effectively in rice.Trchil-trangenosis rice has a significantly increased resistance to rice sheath blight disease; zjmsod-trangenosis rice and esjmnsod-trangenosis rice have an enhanced salt tolerance during seed germination and seedling growth stage. This experiment not only provided new resistance resource for rice breeding, but also offered the scientific basis for improving the resistance and yield of rice by transgenic technology.