| 1. |
- Adomas, Aleksandra, et al.
(författare)
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Comparative analysis of transcript abundance in Pinus sylvestris after challenge with a saprotrophic, pathogenic or mutualistic fungus
- 2008
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Ingår i: Tree Physiology. - : Oxford University Press (OUP). - 0829-318X .- 1758-4469. ; 28:6, s. 885-897
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Tidskriftsartikel (refereegranskat)abstract
- To investigate functional differences in the recognition and response mechanisms of conifer roots to fungi with different trophic strategies, Pinus sylvestris L. was challenged with a saprotrophic fungus Trichoderma aureoviride Rifai. The results were compared with separate studies investigating pine interactions with a pathogen, Heterobasidion annosum (Fr.) Bref. sensu stricto and an ectomycorrhizal symbiont, Laccaria bicolor Maire (Orton). Global changes in the expression of 2109 conifer genes were assayed 1, 5 and 15 days after inoculation. Gene expression data from a cDNA microarray were analyzed by the 2-interconnected mixed linear model statistical approach. The total number of genes differentially expressed compared with the uninfected control was similar after challenge with the pathogen and the ectomycorrhizal symbiont, but the number of differentially expressed genes increased over time, for H. annosum, and decreased for L. bicolor. Inoculation of pine roots with T aureoviride resulted overall in a much lower number of genes with changed transcript levels compared with inoculation with H. annosum or L. bicolor. Functional classification of the differentially expressed genes revealed that the ectomycorrhizal fungus triggered transient induction of defence-related genes. The response and induction of defence against the pathogen was delayed and the magnitude increased over time. Thus, there were specific transcriptional responses depending on whether the conifer roots were challenged with mutualistic, saprotrophic or pathogenic fungi. This suggests that pine trees are able to recognize diverse fungal species and specifically distinguish whether they are pathogenic, neutral or beneficial microbial agents.
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| 2. |
- Nahalka, J, et al.
(författare)
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Elicitation of plumbagin by chitin and its release into the medium in Drosophyllum lusitanicum Link. suspension cultures
- 1998
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Ingår i: Biotechnology letters. - 0141-5492 .- 1573-6776. ; 20:9, s. 841-845
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Tidskriftsartikel (refereegranskat)abstract
- Polysaccharides (chitin/pectin) that are involved in the interactions between plants and microorganisms were applied to the cultured cells of Drosophyllum lusitanicum. In the case of chitin addition, elicitation and crystallization of plumbagin in the medium were observed. N-Acetylchitooligosaccharides smaller than heptamers [(GlcNAc)(n) (n<7)] elicited the biosynthesis of plumbagin but did not increase the hypersensitive response (HR). On the other hand, carboxymethylchitin (DP similar to 200) led to the accumulation of plumbagin in cells and to HR death as well as to the lysis of the cells and release of plumbagin into the medium. The response of cultured cells to the N-Acetylchitosaccharides varied depending on the chemo/physiological conditions of the cells. Addition of pectin (1 g/l) resulted in enhanced HR and decreased biosynthesis of plumbagin.
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| 3. |
- Olivain, C, et al.
(författare)
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Colonization of tomato root by pathogenic and nonpathogenic Fusarium oxysporum strains inoculated together and separately into the soil
- 2006
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Ingår i: Applied and Environmental Microbiology. - 0099-2240 .- 1098-5336. ; 72:2, s. 1523-1531
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Tidskriftsartikel (refereegranskat)abstract
- In soil, fungal colonization of plant roots has been traditionally studied by indirect methods such as microbial isolation that do not enable direct observation of infection sites or of interactions between fungal pathogens and their antagonists. Confocal laser scanning microscopy was used to visualize the colonization of tomato roots in heat-treated soil and to observe the interactions between a nonpathogenic strain, Fo47, and a pathogenic strain, Fo18, inoculated onto tomato roots in soil. When inoculated separately, both fungi colonized the entire root surface, with the exception of the apical zone. When both strains were introduced together, they both colonized the root surface and were observed at the same locations. When Fo47 was introduced at a higher concentration than Fo18, it colonized much of the root surface, but hyphae of Fo18 could still be observed at the same location on the root. There was no exclusion of the pathogenic strain by the presence of the nonpathogenic strain. These results are not consistent with the hypothesis that specific infection sites exist on the root for Fusarium oxysporum and instead support the hypothesis that competition occurs for nutrients rather than for infection sites.
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