Effects of external phosphate concentration on glucose-6-phosphate dehydrogenase gene expression in the arbuscular mycorrhizal fungus Glomus intraradices.
Specific primers were developed to amplify a 227 bp segment of the arbuscular mycorrhizal fungus Glomus intraradices gene encoding glucose-6-phosphate dehydrogenase (G6PDH), an enzyme involved in the pentose phosphate pathway. G6PDH gene expression was measured by real-time quantitative reverse transcriptase-polymerase chain reaction in response to phosphorus (P) concentrations in the growth medium of colonized transformed carrot roots. We investigated the effects of different P concentration treatments on carbon (C) metabolism within the intraradical mycelia of G. intraradices. The results showed a significant (P=0.017) down-regulation of G6PDH expression in the intraradical mycelia of G. intraradices cultures grown in high P than low P conditions but no significant difference in regulation in excessive P concentrations when compared with the low P or high P concentrations. These results indicate that a reduction in the C flow from the host could be occurring as a result of elevated P and that a decrease in fungal G6PDH gene expression occurs, but not in the short term (less than 2 h). Reduced C flow from the host could lead to reduced fungal growth and root colonization, as was observed under high soil P conditions.
Stewart
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Microbiology Unit, Department of Natural Resources Sciences, McGill University, Ste-Anne-de-Bellevue, QC, Canada.
Jabaji-Hare
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Driscoll
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D000595:Amino Acid Sequence; D001693:Biological Transport, Active; D004305:Dose-Response Relationship, Drug; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D005954:Glucosephosphate Dehydrogenase / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D038821:Mycorrhizae / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism; D010710:Phosphates / Q000378:metabolism / Q000494:pharmacology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid
D010710:Phosphates; D005954:Glucosephosphate Dehydrogenase