Phosphate systemically inhibits development of arbuscular mycorrhiza in Petunia hybrida and represses genes involved in mycorrhizal functioning

Florence Breuillin, Jonathan Schramm, Mohammad Hajirezaei, Amir Ahkami, Patrick Favre, Uwe Druege, Bettina Hause, Marcel Bucher, Tobias Kretzschmar, Eligio Bossolini, Cris Kuhlemeier, Enrico Martinoia, Philipp Franken, Uwe Scholz, Didier Reinhardt

Research output: Contribution to journalArticlepeer-review

208 Scopus citations

Abstract

Most terrestrial plants form arbuscular mycorrhiza (AM), mutualistic associations with soil fungi of the order Glomeromycota. The obligate biotrophic fungi trade mineral nutrients, mainly phosphate (Pi), for carbohydrates from the plants. Under conditions of high exogenous phosphate supply, when the plant can meet its own P requirements without the fungus, AM are suppressed, an effect which could be interpreted as an active strategy of the plant to limit carbohydrate consumption of the fungus by inhibiting its proliferation in the roots. However, the mechanisms involved in fungal inhibition are poorly understood. Here, we employ a transcriptomic approach to get insight into potential shifts in metabolic activity and symbiotic signalling, and in the defence status of plants exposed to high Pi levels. We show that in mycorrhizal roots of petunia, a similar set of symbiosis-related genes is expressed as in mycorrhizal roots of Medicago, Lotus and rice. Pi acts systemically to repress symbiotic gene expression and AM colonization in the root. In established mycorrhizal roots, Pi repressed symbiotic gene expression rapidly, whereas the inhibition of colonization followed with a lag of more than a week. Taken together, these results suggest that Pi acts by repressing essential symbiotic genes, in particular genes encoding enzymes of carotenoid and strigolactone biosynthesis, and symbiosis-associated phosphate transporters. The role of these effects in the suppression of symbiosis under high Pi conditions is discussed.

Original languageEnglish (US)
Pages (from-to)1002-1017
Number of pages16
JournalPlant Journal
Volume64
Issue number6
DOIs
StatePublished - Dec 1 2010

Keywords

  • arbuscular mycorrhiza
  • carotenoid
  • glomus
  • petunia
  • phosphate
  • symbiosis

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