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Functional diversity in arbuscular mycorrhizal (AM) symbioses: the contribution of the mycorrhizal P uptake pathway is not correlated with mycorrhizal responses in growth or total P uptake
Author(s) -
Smith Sally E.,
Smith F. Andrew,
Jakobsen Iver
Publication year - 2004
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/j.1469-8137.2004.01039.x
Subject(s) - biology , symbiosis , rhizophagus irregularis , hypha , mycorrhiza , botany , glomeromycota , colonisation , fungus , linum , medicago truncatula , arbuscular mycorrhiza , phycomycetes , glomus , root hair , arbuscular mycorrhizal , colonization , horticulture , spore , bacteria , inoculation , ecology , genetics , biochemistry , gene
Summary• We investigated structural and functional diversity in arbuscular mycorrhizal (AM) symbioses involving three plant species and three AM fungi and measured contributions of the fungi to P uptake using compartmented pots and 33 P. The plant/fungus combinations varied in growth and P responses. Flax ( Linum usitatissimum ) responded positively to all fungi, and medic ( Medicago truncatula ) to Glomus caledonium and G. intraradices , but not Gigaspora rosea . Tomato ( Lycopersicon esculentum ) showed no positive responses. • Hyphal growth in soil was very low for Gi. rosea and high for both Glomus spp. Hyphal lengths in root + hyphal compartment (RHC) and hyphal compartment (HC) were similar for G. intraradices , but much higher in HC for G. caledonium . • Specific activities of 33 P in plants and soil indicated that fungal P uptake made substantial contributions to five plant/fungus combinations and significant contributions to a further two. G. intraradices delivered close to 100% of the P in all three plants. G. caledonium and Gi. rosea delivered less P. The amount was not related to colonisation or to growth or P responses. • We conclude that: AM colonisation can result in complete inactivation of the direct P uptake pathway via root hairs and epidermis; calculations of AM contributions to P uptake from total plant P will often be highly inaccurate; and lack of plant responsiveness does not mean that an AM fungus makes no contribution to P uptake.