Sessitsch Angela, Reiter Birgit, Berg Gabriele
Department of Bioresources/Microbiology, ARC Seibersdorf research GmbH, Austria.
Can J Microbiol. 2004 Apr;50(4):239-49. doi: 10.1139/w03-118.
To study the effect of plant growth on potato-associated bacteria, the composition and properties of bacteria colonizing the endosphere of field-grown potato were analyzed by a multiphasic approach. The occurrence and diversity of potato-associated bacteria were monitored by a cultivation-independent approach, using terminal restriction fragment length polymorphism analysis of 16S rDNA. The patterns obtained revealed a high heterogeneity of community composition and suggested the existence of plant-specific communities. However, endophytic populations correlated to a certain extent with plant growth performance. Endophytes were also isolated from plants that grew well or grew poorly and were identified by partial sequencing of the 16S rRNA genes. A broad phylogenetic spectrum was found among isolates and differently growing plants hosted different bacterial populations. In an approach to investigate the plant-growth-promoting potential of potato-associated bacteria, a total of 35 bacteria were screened by dual testing for in vitro antagonism towards (i) the fungal pathogens Verticillium dahliae, Rhizoctonia solani, Sclerotinia sclerotiorum, and Phytophthora cactorum and (ii) the bacterial pathogens Erwinia carotovora, Streptomyces scabies, and Xanthomonas campestris. The proportion of isolates with antagonistic activity was highest against Streptomyces sp. (43%) followed by those against Xanthomonas sp. (29%). As all plants showed more or less severe disease symptoms of scab disease caused by Streptomyces scabies, we assume that the presence of the pathogen induced the colonization of antagonists. The antifungal activity of the isolates was generally low. The biotechnological potential of endophytic isolates assessed by their antagonistic activity and by in vitro production of enzymes, antibiotics, siderophores, and the plant growth hormone indole-1,3-acetic acid was generally high. Overall, seven endophytes were found to antagonize fungal as well as bacterial pathogens and showed a high production of active compounds and were therefore considered promising biological control agents.
为研究植物生长对马铃薯相关细菌的影响，采用多相方法分析了田间种植马铃薯内生菌的细菌组成和特性。通过非培养方法，利用16S rDNA的末端限制性片段长度多态性分析，监测马铃薯相关细菌的发生和多样性。所得模式显示群落组成具有高度异质性，并表明存在植物特异性群落。然而，内生菌群在一定程度上与植物生长性能相关。还从生长良好或生长不良的植物中分离出内生菌，并通过16S rRNA基因的部分测序进行鉴定。在分离物中发现了广泛的系统发育谱，不同生长状态的植物含有不同的细菌种群。为研究马铃薯相关细菌促进植物生长的潜力，通过双重测试对总共35种细菌进行了筛选，以检测它们对（i）真菌病原体大丽轮枝菌、立枯丝核菌、核盘菌和恶疫霉，以及（ii）细菌病原体胡萝卜软腐欧文氏菌、疮痂链霉菌和野油菜黄单胞菌的体外拮抗作用。具有拮抗活性的分离物比例最高的是对链霉菌属（43%），其次是对黄单胞菌属（29%）。由于所有植物都或多或少表现出由疮痂链霉菌引起的疮痂病的严重症状，我们推测病原体的存在诱导了拮抗物的定殖。分离物的抗真菌活性普遍较低。通过拮抗活性以及体外酶、抗生素、铁载体和植物生长激素吲哚-1,3-乙酸的产生来评估内生分离物的生物技术潜力普遍较高。总体而言，发现有七种内生菌对真菌和细菌病原体均有拮抗作用，并表现出高活性化合物产量，因此被认为是有前景的生物防治剂。
