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Constitutive expression of a celery mannitol dehydrogenase in tobacco enhances resistance to the mannitol‐secreting fungal pathogen Alternaria alternata
Author(s) -
Jennings Dianne B.,
Daub Margaret E.,
Pharr D. Mason,
Williamson John D.
Publication year - 2002
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1046/j.1365-313x.2001.01399.x
Subject(s) - mannitol , alternaria alternata , biology , microbiology and biotechnology , pathogen , alternaria , transgene , reactive oxygen species , biochemistry , botany , gene
Summary Our previous observation that host plant extracts induce production and secretion of mannitol in the tobacco pathogen Alternaria alternata suggested that, like their animal counterparts, plant pathogenic fungi might produce the reactive oxygen quencher mannitol as a means of suppressing reactive oxygen‐mediated plant defenses. The concurrent discovery that pathogen attack induced mannitol dehydrogenase (MTD) expression in the non‐mannitol‐containing host tobacco suggested that plants, unlike animals, might be able to counter this fungal suppressive mechanism by catabolizing mannitol of fungal origin. To test this hypothesis, transgenic tobacco plants constitutively expressing a celery Mtd cDNA were produced and evaluated for potential changes in resistance to both mannitol‐ and non‐mannitol‐secreting pathogens. Constitutive expression of the MTD transgene was found to confer significantly enhanced resistance to A. alternata , but not to the non‐mannitol‐secreting fungal pathogen Cercospora nicotianae . These results are consistent with the hypothesis that MTD plays a role in resistance to mannitol‐secreting fungal plant pathogens.