Arbuscular mycorrhizal fungi contribute to phosphorus uptake by wheat grown in a phosphorus-fixing soil even in the absence of positive growth responses

New Phytol. 2006;172(3):536-43. doi: 10.1111/j.1469-8137.2006.01846.x.


We used 32P to quantify the contribution of an arbuscular mycorrhizal (AM) fungus (Glomus intraradices) to phosphorus (P) uptake by wheat (Triticum aestivum), grown in compartmented pots. The soil was from a major cereal-growing area, the Eyre Peninsula, South Australia; it was highly calcareous and P-fixing. Fertilizer P was added to soil at 20 mg kg(-1), as solid or liquid. Two extraction methods were used to estimate plant-available P. Fungal colonization was well established at harvest (36 d). Application of P decreased both colonization and hyphal length density in soil, with small differences between different P fertilizers. Plants showed large positive responses in terms of growth or total P uptake to all P additions, and showed no positive (or even negative) responses to AM colonization, regardless of P application. 32P was detected only in AM plants, and we calculated that over 50% of P uptake by plants was absorbed via AM fungi, even when P was added. The results add to the growing body of knowledge that 'nonresponsive' AM plants have a functional AM pathway for P transfer to the plant; it should not be ignored in breeding plants for root traits designed to improve P uptake.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Mycorrhizae / physiology*
  • Phosphorus / chemistry*
  • Phosphorus / metabolism*
  • Phosphorus Radioisotopes / chemistry
  • Phosphorus Radioisotopes / metabolism
  • Soil / analysis*
  • Triticum / growth & development
  • Triticum / metabolism*
  • Triticum / microbiology*


  • Phosphorus Radioisotopes
  • Soil
  • Phosphorus