The Presence of the Hairy-Root-Disease-Inducing (Ri) Plasmid in Wheat Endophytic Rhizobia Explains a Pathogen Reservoir Function of Healthy Resistant Plants
| Autor: | Yui Kataoka, Hiroyuki Sawada, Katsunori Suzuki, Akio Tani, Aya Okamoto, Byoungwoo Kang, Kazuhide Rikiishi, Shinji Yamamoto, Taichi Maeshige |
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| Jazyk: | angličtina |
| Rok vydání: | 2020 |
| Předmět: |
0106 biological sciences
Species complex Agrobacterium Biovar Virulence Biology 01 natural sciences Applied Microbiology and Biotechnology Endophyte Rhizobia Microbiology 03 medical and health sciences Plant Microbiology Endophytes Triticum 030304 developmental biology Disease Reservoirs Plant Diseases 0303 health sciences Ecology Genomovar food and beverages Hordeum biology.organism_classification Plant disease Agrobacterium tumefaciens 010606 plant biology & botany Food Science Biotechnology Plasmids |
| Zdroj: | Appl Environ Microbiol |
| Popis: | Rhizobium radiobacter species complex (biovar 1 Agrobacterium) has been known for the crown-gall and hairy-root disease causative pathogens. Strains within this complex were also found as endophytes from many plant species with no symptom. The aim of this study is to reveal the endophyte variation of this complex and how these endophytic strains differ from pathogenic strains. In this study we devised a simple but effective screening method by exploiting the high resolution power of mass spectrometry. We screened endophyte isolates from young wheat and barley plants, which are resistant to the diseases, and identified seven isolates from wheat as members in the R. radiobacter species complex. Through further analyses, we assigned five strains to the genomovar (genomic group) G1 and two strains to G7 in the species. Notably, these two genomovar groups harbor many known pathogenic strains. In fact, the two G7 endophyte strains showed pathogenicity on tobacco, as well as the virulence prerequisites including a 200-kbp Ri plasmid. All of the five G1 strains possessed a 500-kbp plasmid, which is present in well-known crown-gall pathogens. These data strongly suggest a role of healthy wheat plants as a reservoir for pathogenic strains of this species. IMPORTANCE Crown gall and hairy root diseases exhibit very wide host-plant ranges that cover gymnosperm and dicot plants. Rhizobium radiobacter species complex is the representative species that harbor causative agents of the two diseases. Recently, a number of endophyte isolates from many plant species have been assigned to this species complex. We isolated seven endophyte strains belonging to the species complex from wheat plants, and revealed their genomovar affiliations and plasmid profile. The significance of this study is the finding of the genomovar correlation between the endophytes and the known pathogens, the presence of a virulence ability in two of the seven endophyte strains, and the high ratio of the pathogenic strains in the endophyte strains. This study therefore provides convincing evidences that could unravel the mechanism to maintain pathogenic agents of this species and to deliver them to susceptible plants sporadically. |
| Databáze: | OpenAIRE |
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