| Orchardgrass(Dactylis glomerata L.)is the gramineous inflorescences perennial plants of the genus,it is important to temperate herbage,widely grown in southwest area.Endophytes have attracted much attention due to their functions in host growth and disease resistance,but there have been no reports on endophytes in Orchardgrass.In this study,endophytes were isolated and identified,and promoters were screened from nutrient improvement ability,auxin secretion and plant growth promotion.The disease resistance of 6 common pathogenic bacteria was screened from their inhibitory rate,cellulase,lysozyme,amylase activities and field rust resistance ability,which laid a foundation for the development and utilization of endophytes of Orchardgrass and the improvement of yield and quality of Orchardgrass.The main research contents and results are as follows:1.Isolation and identification of endophytes in samples from different regions(Ya'an,Chongqing,Chengdu),different orchardgrass varieties,and different organs(root,stem,and leaf).A total of 21 endophytic strains of Orchardgrass were obtained,including 8 bacterial strains and 13 fungal strains.The number of endophytes isolated from different organs varied greatly,and the number of endophytes obtained from the roots was 12 strains,accounting for more than 57% of the total.Bacillus cereus and Bacillus Thuringiensis are the dominant bacteria,accounting for 75% of the total bacteria,including Mycoides,Bacillus Cereus and Bacillus Thuringiensis.Fungi are divided into Fusarium,Trichoderma sp.,and Aspergillus,of which Trichoderma is the dominant group.2.Twenty-one strains of orchargrass endophytes were selected as the research objects to screen their ability of nutrient improvement and auxin secretion to promote growth.Pot experiment showed that 21 endophytic bacteria had certain growth promoting effect compared with the control,among which endophytic bacteria "TYG2X"(Myroides odoratimimus),auxin secretion amount was 52.57 g/ml,the level was significantly higher than other strains,and also had the ability to dissolve phosphorus and potassium,at the same time,it showed the strongest growth promoting ability in pot experiment.Bacillus sp.And Bacillus Cereus 344 were two strains with strong pro-growth effects and complete functions.Leaf length and root length were significantly positively correlated with the phosphorus solubility of the strain(P?0.01),and significantly positively correlated with the auxin secretion of the strain(P?0.05).3.The biocontrol ability of endophytic bacteria and fungi of Orchardgrass was determined.The results showed that the 13 strains of orchardgrass endophytic fungi isolated in this study had strong antagonistic ability to 6 common pathogenic bacteria(Fusarium oxysporum,vermicularis spore,pantoplasm,anthrax,polygonum fungicum,Nigrospora Oryzae),and most fungi had high lysozyme activity.Compared with endophytic fungi,endophytic bacteria were less antibacterial."344G2Z"(Trichoderma sp.)is an endophyte with the strongest inhibition rate among the isolated strains,and is also a Trichoderma strain.For Phoma Exigua,Fusarium Tricinctum,Cladosporium tenuissimum,Pantoea agglomerans,Nigrospora oryzae,Colletotrichum Cliviicola,the content was 100%,78%,100%,91%,78%.4.Four endophytic strains("344G2Z","344J1X","CFY1X","TYG2X")with strong growth promotion and disease resistance were screened for field experiments.Compared with the control group,the incidence of rust of the four endophytic bacteria was lower than that of the control group,and the relative control effects were 62.16%,38.74%,41.44% and 60.36%,respectively.Four endophytes with good disease-promoting and disease-preventing functions were obtained through screening: "344G2Z","344J1X","CFY1X" and "TYG2X".The results indicated that there should be more extensive research approaches and application methods in the field of disease resistance and growth promotion of endophyte of S.Orchardgrass,such as the mechanism of disease resistance and the utilization of compound strains,etc. |
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