Abstracts |
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. |