Abstract
Ascorbate is a major antioxidant and radical scavenger in plants. Monodehydroascorbate reductase (MDAR) and dehydroascorbate reductase (DHAR) are two enzymes of the ascorbate-glutathione cycle that maintain ascorbate in its reduced state. MDAR2 (At3g09940) and DHAR5 (At1g19570) expression was upregulated in the roots and shoots of Arabidopsis seedlings co-cultivated with the root-colonizing endophytic fungus Piriformospora indica, or that were exposed to a cell wall extract or a culture filtrate from the fungus. Growth and seed production were not promoted by Piriformospora indica in mdar2 (SALK_0776335C) and dhar5 (SALK_029966C) T-DNA insertion lines, while colonized wild-type plants were larger and produced more seeds compared to the uncolonized controls. After 3 weeks of drought stress, growth and seed production were reduced in Piriformospora indica-colonized plants compared to the uncolonized control, and the roots of the drought-stressed insertion lines were colonized more heavily by the fungus than were wild-type plants. Upregulation of the message for the antimicrobial PDF1.2 protein in drought-stressed insertion lines indicated that MDAR2 and DHAR5 are crucial for producing sufficient ascorbate to maintain the interaction between Piriformospora indica and Arabidopsis in a mutualistic state.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Arabidopsis / enzymology*
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Arabidopsis / genetics
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Arabidopsis / growth & development
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Arabidopsis / microbiology*
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Arabidopsis Proteins / genetics
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Arabidopsis Proteins / metabolism*
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Basidiomycota / physiology*
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Colony Count, Microbial
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Defensins / genetics
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Defensins / metabolism
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Dehydroascorbic Acid / metabolism
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Droughts
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Fungal Proteins / genetics
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Fungal Proteins / metabolism
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Gene Expression Regulation, Enzymologic
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Gene Expression Regulation, Plant
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NADH, NADPH Oxidoreductases / genetics
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NADH, NADPH Oxidoreductases / metabolism*
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Oligonucleotide Array Sequence Analysis
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Oxidoreductases / genetics
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Oxidoreductases / metabolism*
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Plant Leaves / enzymology
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Plant Leaves / genetics
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Plant Leaves / microbiology
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Plant Roots / enzymology
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Plant Roots / genetics
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Plant Roots / microbiology
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Plant Shoots / enzymology
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Plant Shoots / genetics
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Plant Shoots / microbiology
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RNA, Messenger / genetics
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RNA, Messenger / metabolism
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Seedlings / metabolism
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Seedlings / microbiology
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Seeds / enzymology
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Seeds / growth & development
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Seeds / microbiology
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Stress, Physiological
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Symbiosis*
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Up-Regulation
Substances
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Arabidopsis Proteins
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Defensins
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Fungal Proteins
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PDF1.2 protein, Arabidopsis
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RNA, Messenger
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Oxidoreductases
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MDAR2 protein, Arabidopsis
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NADH, NADPH Oxidoreductases
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glutathione dehydrogenase (ascorbate)
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Dehydroascorbic Acid