Diversity Of Endophytic Fungi In Tobacco And Screening On Strains With Growth-promoting And Heavy Metal Resistant

Studying on endophytic fungi would contribute importantly to the ecology, evolutionary mechanism and application of higher fungi. In this paper, we focus on the endophytic fungal in10kinds of tobacco which collected from Yunnan Province. Through isolation and molecular biology methods, we do a preliminary study on the diversity of endophytic fungi in the tobaccos, analyses the composition and the characteristics of diversity of endophytic fungi, then screening the functional strains which promote growth and improve tobacco resistance to heavy metal. The main results were as follows:(1)63,99and37endophytic fungal strains were isolated from186root tissues,179stem tissues and176leave tissues and isolate rate of roots, stems and leaves were33.9%,55.3%and21.2%, respectively.185endophytic fungal strains were identified to23species including Alternaria sp.1, Arthopyreniaceae sp.l, Cladosporium sp.1, Clonostachys sp.1, Fusarium sp.1, Fusarium sp.1, Fusarium sp.3, Fusarium sp.4, Mycosphaerella sp.l, Paecilomyces sp.1, Phoma sp.1, Phoma sp.1, Phoma sp.3, Phoma sp.4, Phoma sp.5, Phoma sp.6, Plectosphaerella sp.1, Plectosphaerella sp.2, Pyrenochaeta sp.1, Pyrenochaeta sp.1, Rhizopycnis sp.1, Setophoma sp.1and Trichoderma harzianum. Among them, the most abundant genera were Phoma, Alternaria and Fusarium. The relative frequencies of three genera were32.4%,26.5%and12.4%, respectively.Composition of isolated strains from different tissues indicated that endophytic fungi in roots, stems and leaves were comprised of15,13and7species, respectively. The most abundant genera in roots were Fusarium and Phoma, which was accounted for60.3%of the total endophytic fungi. Phoma and Alternaria were the most abundant genera in stems, which accounted for76.3%of total endophytic fungi. Alternaria was the most abundant genera in leaves, which accounted for52.9%of the total endophytic fungi. Except Cladosporium, Clonostachys and Phoma distributed widely in roots, stems and leaves, endophytic fungi have tissue specificity to some extent, such as Alternaria distributed only in stems and leaves, Fusarium in roots and stems.(2) Among199strains,5strains (YNNE005, YNNEO53, YNNE191, YNNE193and YNNE199) with growth-promotion to tobacco steadily were screened out by co-culture between tobacco and endophytic fungus in petri dishes. After treated with an endophytic fungus, the increasing rate of dry weight of tobacco leaves was605.5%,235.7%,358.3%,232.2%and408.5%, respectively. The increasing rate of dry weight of tobacco roots was955.3%,578.9%,607.9%,447.4%and881.6%, respectively.Tobacco seedlings colonized by YNNE005, YNNE053, YNNE191, YNNE193and YNNE199by co-culture in petri dishes, shown significant growth-promotion effect in pot culture as well. The increasing rate of dry weight of tobacco leaves was52.6%,44.3%,58.3%,47.4%and31.1%, respectively.(3) Endophytic fungi fertilizer produced by solid-state fermentation using wheat as substrate in the preliminary study, the increasing rate of dry weight of tobacco leaves were77.9%,38.3%,4.3%,9.8%and13.1%, respectively, after treated with fertilizers of YNNE005, YNNE053, YNNE191, YNNE193and YNNE199.(4)4strains can reduce the content of heavy metal Cd2+in tobacco leaves in a preliminary screening, the decreasing rate of the content of heavy metal Cd2+in tobacco leaves after treated with YNNE005, YNNE053, YNNE191and YNNE193were25.3%,14.3%,27.1%,23.5%, respectively.