Effects Of Endophytic Fungi Reinfection On Fungal Community Structure, Physiological And Biochemical Of Tobacco

Plant endophytic fungi is a fungi group growing in plant living tissues, but can not cause any obviously plant disease symptoms. Endophytic fungi widely distributed in variety plant tissues and played important role in plant growth, development, stress resistance and secondary metabolism process. Understanding the relationship between endophytic fungi and host plant were help us developing new fungi resource for crop culture regulation.Nicotiana tabacum belong to Solanaceae annual herb, is an important economic crop and play an important role in Gross National Product in China. Facing to the competitions and challenges from the domestic and international tobacco industry, it is great significance that improving the quality of tobacco to raise the international competitiveness of China's tobacco industry. In this paper, the endophytic fungi isolated from tobacco leaf was infected back to healthy growth tobacco leaf, then, we studied the effect of endophytic fungal community structure, physiological and biochemical on tobacco leaf. The preliminary results are shown as follows:1.When endopphytic fungi infected back to new tobacco leaf, the genera and diversity index of endopphytic fungi in tobacco leaf decreased,while the quantity and isolation rate of endopphytic fungi in tobacco leaf increased. The dominance of dominant endophytic fungi increased and the endophytic fungal community structure became simpler. The most significant effect was found when infected with the endophytic fungi of Chaetomium globosum and Alternaria alternata.2.The study of tobacco agronomical traits shows:tobacco stem diameter increased significantly when treated with Colletotrichum boninense, Xylaria sp.and Chaetomium globosum, while tobacco leaf area were increased significantly when treated with Fusarium sambucinum, Fusarium oxysporum, Fusarium lateritium and Alternaria alternata. The sponge tissue thickness of tobacco leaves were found decreased when treated with endophytic fungi, but the tissue ratio of tobacco leaf increased.The treatment of endophytic fungi lead to tobacco leaves thinner.3.Fusarium equiseti,Colletotrichum boninense,Fusarium sambucinum and Xylaria sp. treated tobacco significantly decreased the risk of tobacco powery mildew, the inhibition effect were more than70%. However, Chaetomium globosum treated tobacco increased the incidence and aggravate symptoms of tobacco powery mildew.4.The net photosynthetic rate, transpiration rate and stomatal conductance of tobacco leaf increased when treated with endophytic fungi.At temperature rising stage, the effects were significantly when treated with Xylaria sp., Fusarium oxysporum and Fusarium lateritium; At the highest temperature stage, Chaetomium globosum and Fusarium lateritium treated tobacco appear significantly affected; but at temperature decreasing stage, the effects of Fusarium equiseti, Colletotrichum boninense and Fusarium sambucinum are significant.5.The protease,amylase and cellulase activity of tobacco leaf improved significantly when treated with Xylaria sp.,Fusarium lateritium and Alternaria alternata. Fusarium sambucinum and Xylaria sp. promoted the protein,starch,cellulose content of tobacco more harmonious and much closer to the high quality standard of tobacco.6.The content of total sugar improved and sugar/nitrogen, sugar/nicotine were increased when tobacco leaf was treated with endophytic fungi agents, while the content of total nitrogen,nicotineand nitrogen/nicotine decreased.The content of total sugar,total nitrogen and nicotine of tobacco leaf improved more harmonious and much closer to the high quality standard of tobacco when treated with endophytic fungi agents.7.The volatile constituents content of carbonyls, organic acids, phenolic, esters, neophytadiene et al. in tobacco leaf increased when treated with endophytic fungi agents,but the content of nicotine in tobacco leaf decreased.The results showed that some endophytic fungi isolated from tobacco leaves not only improved growth, development, and other physiological and biochemical indexes of tobacco leaf significantly, but also decreased the risk of tobacco powery mildew significantly.The results will provide valuable informaitons for further exploite and utilize of endophytic fungi resource.