Browsing by Subject "BIOCONTROL"

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  • Zhao, Ke; Li, Jing; Zhang, Xiaoyue; Chen, Qiang; Liu, Maoke; Ao, Xiaolin; Gu, Yunfu; Liao, Decong; Xu, Kaiwei; Ma, Monggeng; Yu, Xiumei; Xiang, Quanju; Chen, Ji; Zhang, Xiaoping; Penttinen, Petri (2018)
    Many of the plant associated microbes may directly and indirectly contribute to plant growth and stress resistance. Our aim was to assess the plant growth-promoting and antimicrobial activities of actinobacteria isolated from Glycyrrhiza inflata Bat. plants to find strains that could be applied in agricultural industry, for example in reclaiming saline soils. We isolated 36 and 52 strains that showed morphological characteristics of actinobacteria from one year old and three year old G. inflata plants, respectively. Based on 16S rRNA gene sequence analysis, the strains represented ten actinobacterial genera. Most of the strains had plant growth promoting characteristics in vitro, tolerated 200 mM NaCl and inhibited the growth of at least one indicator organism. The eight selected Streptomyces strains increased the germination rate of G. inflata seeds under salt stress. In addition, the four best seed germination promoters promoted the growth of G. inflata in vivo. The best promoters of G. inflata growth, strains SCAU5283 and SCAU5215, inhibited a wide range of indicator organisms, and may thus be considered as promising candidates to be applied in inoculating G. inflata.
  • Kovalchuk, Andriy; Mukrimin, Mukrimin; Zeng, Zhen; Raffaello, Tommaso; Liu, Mengxia; Kasanen, Risto; Sun, Hui; Asiegbu, Fred O. (2018)
    Plant microbiome plays an important role in maintaining the host fitness. Despite a significant progress in our understanding of the plant microbiome achieved in the recent years, very little is known about the effect of plant pathogens on composition of microbial communities associated with trees. In this study, we analysed the mycobiome of different anatomic parts of asymptomatic and symptomatic Norway spruce trees naturally infected by Heterobasidion spp. We also investigated the primary impact of the disease on the fungal communities, which are associated with Norway spruce trees. Our results demonstrate that the structure of fungal communities residing in the wood differed significantly among symptomatic and asymptomatic Heterobasidion-infected trees. However, no significant differences were found in the other anatomic regions of the trees. The results also show that not only each of individual tree tissues (wood, bark, needles and roots) harbours a unique fungal community, but also that symptomatic trees were more susceptible to co-infection by other wood-degrading fungi compared to the asymptomatic ones.
  • Hiltunen, Lea H.; Tarvainen, Oili; Kelloniemi, Jani; Tanskanen, Jaakko; Karhu, Jouni; Valkonen, Jari P. T. (2021)
    Disease suppressive soils are important for managing soil-borne diseases that cannot be controlled with chemicals. One such disease is the potato common scab caused by Streptomyces species. Suppressiveness against common scab can develop spontaneously in fields where potato is grown for years without interruption, and this has been attributed to non-pathogenic Streptomyces strains. Streptomyces spp. have been used as inoculants in biological control, but their long-term effects have gained less attention. In our previous studies, a nonpathogenic Streptomyces strain (Str272) isolated from a potato common scab lesion suppressed common scab in field trials lasting over 5 years. In this study, bacterial communities in the tuberosphere i.e. in the soil adjacent to potato tubers, were analysed by next generation sequencing (NGS). The aim was to compare bacterial communities in untreated control plots to those in which seed tubers were treated with Str272 in one or several growing seasons. Str272 applications increased soil bacterial diversity and affected the bacterial composition in the potato tuberosphere. The most pronounced differences were observed between the untreated control and the treatments in which the antagonist had been applied in three or four consecutive years. The differences remained similar until the following growing season. Bacterial composition after repeated antagonist applications was associated with lower common scab severity. The antagonist applications had no or only slight effect on the number or abundance of OTUs belonging to Actinobacteria or Streptomyces, and no differences in quantities of pathogenic Streptomyces populations were detected by qPCR. This indicates that suppression of common scab by Str272 may not be based on direct effect on the common scab pathogens but is more likely to be associated with the alterations of the soil bacterial community. The most abundant bacteria phyla in the potato tuberosphere were Actinobacteria, Proteobacteria and Acidobacteria. However, the OTUs responding greatest to the antagonist treatments belonged to Bacterioidetes and Gemmatimonadetes. Results indicate that repeated applications of Str272 can change the bacterial community in the potato tuberosphere and lead to development of soil that is suppressive against potato common scab for several growing seasons after the last application.