JXB Advance Access published online on November 29, 2007
Journal of Experimental Botany, doi:10.1093/jxb/erm230
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© 2007 The Author(s).
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/2.0/uk/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
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RESEARCH PAPER |
Role of ethylene in the protection of tomato plants against soil-borne fungal pathogens conferred by an endophytic Fusarium solani strain*
1National Agricultural Research Foundation, Institute of Kalamata, 87 Lakonikis St., Kalamata, 24100, Greece
2University of Thessaly, Department of Biochemistry and Biotechnology, Ploutonos 26 & Aeolou, Larissa, 41221, Greece
3Agricultural University of Athens, Department of Natural Resources and Agricultural Engineering, Soils and Agricultural Chemistry Laboratory, 75 Iera Odos St., Athens, 118 55, Greece
4University of Athens, Faculty of Biology, Department of Botany, Athens, 15784, Greece
To whom correspondence should be addressed. E-mail: kalpapad{at}bio.uth.gr
An endophytic fungal isolate (Fs-K), identified as a Fusarium solani strain, was obtained from root tissues of tomato plants grown on a compost which suppressed soil and foliar pathogens. Strain Fs-K was able to colonize root tissues and subsequently protect plants against the root pathogen Fusarium oxysporum f.sp. radicis-lycopersici (FORL), and elicit induced systemic resistance against the tomato foliar pathogen Septoria lycopersici. Interestingly, attenuated expression of certain pathogenesis-related genes, i.e. PR5 and PR7, was detected in tomato roots inoculated with strain Fs-K compared with non-inoculated plants. The expression pattern of PR genes was either not affected or aberrant in leaves. A genetic approach, using mutant tomato plant lines, was used to determine the role of ethylene and jasmonic acid in the plant's response to infection by the soil-borne pathogen F. oxysporum f.sp. radicis-lycopersici (FORL), in the presence or absence of isolate Fs-K. Mutant tomato lines Never ripe (Nr) and epinastic (epi1), both impaired in ethylene-mediated plant responses, inoculated with FORL are not protected by isolate Fs-K, indicating that the ethylene signalling pathway is required for the mode of action used by the endophyte to confer resistance. On the contrary, def1 mutants, affected in jasmonate biosynthesis, show reduced susceptibility to FORL, in the presence Fs-K, which suggests that jasmonic acid is not essential for the mediation of biocontrol activity of isolate Fs-K.
Key words: Biocontrol, endophyte, ethylene, induced systemic resistance, jasmonic acid, Solanum lycopersicum
* Accession numbers: The GenBank accession numbers for the 18S rRNA gene and ITS-5.8S rRNA gene sequences of Fusarium solani strain Fs-K are EF621487 and EF621488, respectively.
Present address: National Agricultural Research Foundation, Institute of Chania, 73100 Chania, Crete, Greece.
Received 19 July 2007; Revised 27 August 2007 Accepted 30 August 2007