Isolation And Identification Of Endophytic Fungi Within Allelopathic Rice And Its Biological Characteristics Testing

Endophytic fungi was found in various plants,which can promote plant growth,increase plant resistance to various environmental stresses and improve allelopathy of plants.As a special germ plasm resources,allelopathic rice also contains a variety of endophytic fungi.Therefore,this study tentatively explored the species and distribution of endophytic fungi within allelopathic rice,along with its biological characteristics,in order to provide a basis for further study of its mechanism and application value.Endophytic fungi were detected and isolated from allelopathic rice and non-allelopathic rice.The results showed that 107 purified strains were isolated from 6 rice materials,in which 54 isolates of endophytic fungi were isolated from allelopathic rice and12 species of 16 genera were identified by rDNA-ITS sequence analysis.Aspergillus,Penicillium and Fusarium were the dominant species in allelopathic rice with the relative isolate frequency 29.63%,16.67% and 12.96% respectively.The community composition of the fungi in different tissues varied significantly.Endophytic fungi were frequently isolated from stems of allelopathic rice with the relative isolate frequency34.33%.Species frequently isolated from stems and roots were those of Aspergillus and Penicillium respectively.In addition,most of the endophytic fungi were isolated in the tillering stage of rice,followed by seedling stage.In specific,Aspergillus were isolated at the different stages of rice growth,and Penicillium could be isolated at the seedling and tillering stage,while Fusarium isolated only at the tillering and heading stage.In order to study the biological characteristics of endophytic fungi within allelopathic rice strain 6173,the effects of 12 different fungi fermentation on the growth and physiological characteristics of non-allelopathic rice and barnyard grass were evaluated by measuring the germination rates,stem length,fresh weight and some protective enzymes in vitro.The results showed that A.tubingensis and R.mucilaginosa significantly improved germination rate of rice seeds,while F.avenaceum,P.digitatum and R.mucilaginosa could inhibit barnyard grass' germination.Intriguingly,3 of 12 endophytic fungi broth had a significant role in promoting rice seedling growth,among which R.mucilaginosa increased its stem height by 45.10% compared with the control group,whereas 4 strains had the restraining ability on barnyard grass,among which A.niger and C.purpurea significantly suppressed its growth by 32.88% and 32.54% respectively.In additon,A.tubingensis and R.mucilaginosa significantly increased the fresh weight of rice by 11.01% and14.68%.Moreover,this study found that 3 kinds of fungi broth decreased barnyard grass' fresh weight.The inhibition rate of C.purpurea was 31.82% higher than that of control group.Further studies conclusively showed that A.tubingensis could improve lipase activity of rice by 175.05% at 96 h.On the contrary,R.mucilaginosa significantly reduced lipase activity of barnyard grass seed by 82.61% at 24 h,and 36.50% at 96 h.In addition,A.tubingensis promoted SOD and POD activity of rice by 33.60% and 44.64%respectively,and it also reduced POD activity of barnyard grass by 44.11% compared with the control group.To explore the feasibility of A.tubingensis and R.mucilaginosa in field application,the effects of three different concentrations of fungal fermentation broth on the growth and physiological characteristics of rice and barnyard grass were evaluated by seed germination and seedling growth in vitro and by pot experiments in a greenhouse.The result showed that the 50-fold dilution of A.tubingensis had the most significant effects on promoting growth of rice and barnyard grass.Specifically,the stem height,root length and fresh weight were 13.98%,11.57% and 14.74% higher than the controls respectively in A.tubingensis trentment group,while its PAL and CAT activity also enhanced significantly.However,the 5-fold dilution of R.mucilaginosa inhibited PAL activity of barnyard grass by87.41% and 77.96% at 24 h and 48 h respectively,which also restrained its POD activity.The results of pot experiment showed that the 50-fold dilution of A.tubingensis stimulated the growth of barnyard grass and advanced its tiller stage,while the 5-fold dilution of R.mucilaginosa significantly inhibited its growth condition,which indicated that R.mucilaginosa has positive significance for improving the competitiveness of rice to barnyard grass,further inducing the allelopathic potential of non-allelopathic rice.In summary,the variety of species and community structure of endophytic fungi may be effected by the variation of growth condition of allelopathic rice,and its colonization abilities were also different.After a preliminary study on biological characteristics of endophytic fungi,A.tubingensi,which may promote the growth of rice,and R.mucilaginosa,which may improve the allelopathic potential of rice,were selected,which could be applied as a novel biological source of agricultural production.