| This study was performed to investigate Epichloe endophyte that is symbiotic in tissue of an excellent native forage and native grass, Hordeum brevisubulatum, which is tolerant to saline alkaline and distributed in Linze and Yuzhong county of Gansu province. The interaction between endophytic fungus and pathogenic fungi in vitro, detached leaves, whole plant and extraction conditions were studied. The pathogenic fungi include Altemaria alternata, Bipolaris sorokiniana, Clavieps purpurea, Curvularia lunata, Drechslera erythrospila, Fusarium avenaceum, F. semitectum and F. solani. The results showed that:1. All the detached leaves of endophyte-free (E-) H. brevisubulatum inoculated by these 8 fungi appeared obvious lesions in 48 hours. The endophyte-infected (E+) leaves inoculated by D. erythrospila have no lesions within a week. Of the leaves inoculated by B. sorokiniana, C. lunata, F. avenaceum, A. alternata, Fusarium semitectum and Fusarium solani, the number of lesions was about 44%-68% higher on E- than E+ leaves (P<0.05), and the length of lesion was 82%-92% longer on E- than E+ leaves(P<0.05) in the second day to the sixth day. As a whole, the resistance of E+ leaves were stronger than E- leaves. The spore concentration on E+ leaves inoculated by A. alternata, C. lunata, F. avenaceum, F. semitectum and F. solani is 20%-81% of E- leaves. The reaction of H. brevisubulatum-endophytes symbiosis varied with different dpecies of pathogenic fungi.2. The plants height and tillers of E+ and E- H. brevisubulatum potted in the greenhouse both went up along with the time after infected by A. alternata, B. sorokiniana C. lunata, F. avenaceum and F. semitectum. But the E+ showed a more remarkable effect on the height than E-. The aboveground dry weight, roots dry weight and total biomass of E+ is significantly higher than E- after H. brevisubulatum plants that infected by C. lunata, F. avenaceum and F. semitectum(P<0.05). The roots dry weight and total biomass of E+ were significantly higher than E- when The plants infected by A. alternata (P<0.05), but the difference of the aboveground dry weight is not significant (P>0.05). The aboveground dry weight and total biomass of E+ were significantly higher than E- when The plants infected by B. sorokiniana (P<0.05), but the difference of the roots dry weight is not significant (P>0.05).3. After the leaves infected by these five pathogenic fungi, the activity of PAL, SOD, CAT in leaves both of E+ and E-went up, PAL of E+ was 25%-41% higher than E-, SOD of E+ was 20%-35% higher, CAT of E+ was 12%-25% higher. The content of MDA and soluble sugar increased initially but then decreased, MDA of E+ is 19%-42% lower than E-, the soluble sugar of E+ is 9%-16% higher than E-.4. The results of HPLC analysis showed that ergonovine and ergine existed in the E+ drunken horse grass. The concentrations were 26.178 mg-kg-1 and 369.074 mg-kg-1, but these two alkaloids were not detected in the E- extraction. Antifungal activities of the alkaloid extraction from endophyte-infected (E+) and endophyte-free (E-) A inebrians were tested against Alternaria alternate, Bipolaris sorokiniana, Claviceps purpurea, Curvularia lunata, Drechslera erythrospila, Fusarium avenaceum, Fusarium semitectum and Fusarium solani. It was found that both of E+ and E- extract had increasing inhibition on fungal colony and spore germination with increasing concentration, while E+ had stronger inhibition. The inhibition on colony growth and spore germination of F. avenaceum was greatest with 63% and 57%, respectively. The concentration of alkaloid extraction and the spore germination inhibition rate of tested fungi was significantly positive correlation (P<0.05). Endophytic fungi infection increased the antifungal activity of extraction of drunken horse grass. But the mechanism of antifungal activity need the further research. |
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