凤县几种野生植物内生放线菌的分离筛选

用选择性培养基从采自凤县的12种野生植物中分离获得15种放线菌.非寄主作物定殖试验表明分离所获放线菌不仅能够定殖在不同植物体内,而且能定殖在植物的不同部位,具有内生性;皿内拮抗试验结果表明,15株内生放线菌中有2株对5种供试靶标真菌（梨状毛霉菌、西瓜枯萎菌、番茄灰霉菌、粉红聚端孢、苹果炭疽菌）有明显拮抗活性,其中Am3对灰葡萄孢菌抑制率达89.0%.Am5对西瓜枯萎病菌抑制率达81.0%;2株内生放线菌的发酵液对供试靶标真菌也有明显抑制作用,菌体残渣提取物的拮抗活性明显高于发酵滤液提取物.温室番茄、黄瓜防病促生实验结果显示菌株Am3、Am5有较好的防病促生作用,其中经Am3处理过的番茄植株干重比对照植株干重增加120%,对番茄灰霉病的防效达68.9%.

Isolation and Screening of Endophytic Actinomycetes from Several Wildings Collected in Fengxian of Shaanxi Province

Fifteen strains of endophytic actinomycetes from surface-sterilized tissues of 12 plants species collected in Fengxian of Shaanxi province were isolated by selection medium.All of the strains have been successfully reisolated from three plant species with seedings inoculation.The actinomycetes strains could not only colonize on interior and exterior of the plants roots but on the stem and leaves.Fifteen strains had been assayed antagonistic activity in vitro,the results indicated that two strains have better inhibiting effects on target pathogens(Mucor piriformis,Fusarium oxysporum f.sp.niveum,Botrytis cinerea,Trichothecium roseum,Colletotrichum gloesporioide) than the others,89% inhibiting ratio could be gained to Botrytis cinerea by Am3,and 81% inhibiting ratio could be gained to Fusarium oxysporum f.sp.niveum by Am5.The fermentation of two strains also have preferably inhibiting effects on five target pathogens,and the inhibiting effect of extraction from the the filtrate of fermentation by acetone was more evidence than that from the extraction of the mycelia.In the greenhouse study,both the strain Am3 and Am5 can promote the growth of plant,and control the disease of plant.The dry weight of plant increased by 120% after the plant of tomato was treated by Am3,and 68.9% controlling ratio could be gained to Fulvia fulva.