The effect of the endophyte Neotyphodium lolii on susceptibility of perennial ryegrass (Lolium perenne) to ten fungal pathogens in detached leaves was studied. The pathogens were Alternaria alternata, Ascochyta leptospora, Bipolaris sorokiniana, Curvularia lunata, Fusarium acuminatum, F. avenaceum, F. chlamydosporum, F. solani, F. oxysporum, and Gliocladium roseum. In addition, the effect of the endophyte on four pathogens (A. alternata, B. sorokiniana, Curvularia lunata and F. avenaceum) in living plants was studied, and changes in host superoxide dismutase (SOD) or peroxidases (POD) activity were examined. The total lengths of lesions on detached leaves were greater (P<0.05) on Eplants than on E+ plants except for A. leptospora although differences between E+ and E- were not consistently significant at all sample times (days after inoculation).The numbers of lesions were greater (P< 0.05) and the lesions were larger (P<0.05) on intact E- plants than on intact E+ plants for all of the four pathogens. SOD enzyme activity was significantly greater (P<0.05) in E+ plants than in E- plants only for A. alternata, C. lunata, and F. avenaceum. POD enzyme activity was significantly greater (P<0.05) in E+ plants than in E- plants only for C. lunata, B. sorokiniana and the uninoculated control.

通过饲喂试验,研究了带内生真菌(E+)和不带内生真菌(E-)的醉马草对家兔健康的影响。内生真菌的侵染,使醉马草粗脂肪含量显著提高,粗蛋白和粗纤维含量无显著改变。按10 mL /kg体重的剂量灌服E+醉马草水提液,家兔表现出明显的中毒症状;但累计灌服20mL/kg体重的剂量,亦未引致死亡。平均按每kg体重累计饲喂E+醉马草131.6g,可引起家兔中毒;累计饲喂350.9g可使家兔致死,死亡率达66.7%。而灌服和饲喂E-醉马草的家兔则无异常。初步认为,醉马草对家兔的致毒机理是由内生真菌与宿主互作产生的生物碱所致。

综述了国内外近年来关于内生真菌Neot y p hodi um 对禾草类植物抗旱性方面的研究成果。结果表明:与不带菌禾草相比,带菌禾草的抗逆性强、产量高,特别是内生真菌的侵染可增加宿主植物的抗旱性。据报道,内生真菌主要是通过促进植株根系发育、叶片生长、气孔开闭、渗透调节、抗氧化保护系统等来提高禾草类植物的抗干旱胁迫能力。但也有学者认为并非所有内生真菌对宿主禾草的抗旱性都有增益作用,内生真菌与禾草的共生关系还很大程度上决定于宿主、内生真菌基因型和生境的相互关系。在未来的研究中应以内生真菌- 禾草共生体的抗旱机理、生物学特性和群体特征为重点;此外利用真菌-禾草共生体的抗旱特性开展优良牧草草坪草选育,发挥内生真菌在天然草地中的生态作用也是重要的研究方向。

通过测定一系列生理变化指标，研究人工接种条件下禾谷缢管蚜(Rhopalosi p hum padi (L.))对带内生真菌(E+) 与不带菌(E-) 醉马草(A chnatherum inebrians (Hance) Keng) 幼苗的影响。结果表明:在一定时期内，禾谷缢管蚜刺吸可使醉马草幼苗叶片相对含水量和叶绿素含量显著降低(P<0.05)，同一个虫口密度E + 与E-植株之间差异显著(P<0.05)；幼苗体内SOD 活性和POD 活性均随危害时间的延长而显著升高(P<0.05)，同一个虫口密度E+与E-植株之间差异显著(P<0.05)；接种蚜虫可使MDA 和游离脯氨酸的含量显著提高(P<0.05)，同一个虫口密度内E+与E-植株之间差异显著(P<0.05)。综上所述，内生真菌的侵染可以在一定程度上间接影响禾谷缢管蚜取食，进而影响醉马草幼苗生理生化的变化。

在室外盆栽条件下通过比较带内生真菌(E+)与不带内生真菌(E-) 的野大麦(Hordeum brevisubulatum(Trin.) Link)在不同NaCl浓度(0、100 、200 、300 mmol L-1)条件下的生长与生理指标变化，分析了内生真菌对宿主野大麦耐盐性的影响。结果表明：在高盐浓度(300 mmol L-1)下内生真菌显著提高了宿主野大麦分蘖能力、生物量积累、可溶性糖含量、脯氨酸含量、SOD 酶活性(P<0.05)，同时降低了丙二醛含量，说明内生真菌的侵入有利于提高宿主野大麦在室外盆栽条件下的耐盐性。