Preparation Of Carrageenan Oligosaccharide And Its Effect On The Resistance Of TMV In Tobacco

Compared with polysaccharides,the biological activities of oligosaccharides are roughly the same,while the physical and chemical properties of oligosaccharides make it easier to use and develop.So in recent years,in order to discover more of its new biological activity,people have constantly devoted their resources and energy to study oligosaccharides.Carrageenan oligosaccharides is obtained from marine red alga and has been proved to have anti-tumor,antiviral property.We have found that Carrageenan oligosaccharides can protect Nicotiana tabacum from Tobacco mosaic virus(TMV)in a certain extent.We have done the following research in order to explore its mechanism:1.We have fermented Bacillus sp.Car19 to get carrageenase,then we have used it to degrade carrageenan.The result of thin layer chromatography for degradation products show that 85.0% of all degradation products is disaccharide.We have used the degradation products for the following research;2.We have used deionized water and Chitosan oligosaccharides as negative control and positive control respectively.We seted up groups of oligosaccharides with different concentration gradients in reference,then we have sprinkled tobaccoes with corresponding solutions.Through statistical results,we find that tobaccoes which is in groups of Chitosan oligosaccharides and Carrageenan oligosaccharides have delayed the disease time and reduced disease index,comparing with negative control group;3.We have tested the activity of some defensive enzymes using ELISA.The results show the activity of β-1,3-glucan enzyme,SOD(superoxide dismutase)and POD(peroxidase)in experiment groups was higher than those in negative control group;4.We used Real-time PCR to test the expression of some genes.The results show that after inoculated TMV some genes expression,such as Nr CN and MAPK,in experiment groups is higher than control group;5.According to the result of sequencing,we can found that tobacco which was treated by Carrageenan oligosaccharide had many genes expression and metabolic pathways which have been changed.The result show that there are 879 up-regulated expression genes and 664 down-regulated expression genes.We have enriched all differential expression genes using Gene oncology and KEGG,then the result of GO show that those differential expression genes mainly involved in metabolic process,cellular process and catalytic process,and the result of KEGG show that those genes participated in photosynthesis-antenna protein and cutin and wax biosynthesis.