Constitutive expression of a celery mannitol dehydrogenase in tobacco enhances resistance to the mannitol‐secreting fungal pathogen Alternaria alternata

• Published in: The Plant journal : for cell and molecular biology 2002-10, Vol.32 (1), p.41-49
• Main Authors: Jennings, Dianne B., Daub, Margaret E., Pharr, D. Mason, Williamson, John D.
• Format: Article
• Language: English
• Subjects: Agronomy. Soil science and plant productions; Alternaria - growth & development; Alternaria - metabolism; antioxidant; Apium - enzymology; Apium - genetics; Ascomycota - growth & development; Ascomycota - metabolism; Biological and medical sciences; disease resistance; DNA, Complementary - chemistry; DNA, Complementary - genetics; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation, Enzymologic; Gene Expression Regulation, Plant; Genes, Plant - genetics; Genetics and breeding of economic plants; hydroxyl radical; Immunity, Innate - genetics; mannitol; Mannitol - metabolism; Mannitol Dehydrogenases - genetics; Mannitol Dehydrogenases - metabolism; Nicotiana - enzymology; Nicotiana - genetics; Pest resistance; Plant Diseases - genetics; Plant Diseases - microbiology; Plant pathogens; Plants, Genetically Modified; reactive oxygen; Reactive Oxygen Species; Varietal selection. Specialized plant breeding, plant breeding aims
• ISSN: 0960-7412; 1365-313X
• DOI: 10.1046/j.1365-313X.2001.01399.x

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.