Journal Article

Underground friends or enemies: model plants help to unravel direct and indirect effects of arbuscular mycorrhizal fungi on plant competition

Facelli, José M, Christophersen, Helle M, Facelli, Evelina, Andrew Smith, F, Smith, Sally E

2010

Overview

We studied the effects of two arbuscular mycorrhizal (AM) fungi, singly or together, on the outcome of competition between a host (tomato cultivar, wild-type (WT)) and a surrogate nonhost (rmc, a mycorrhiza-defective mutant of WT) as influenced by the contributions of the direct and AM phosphorus (P) uptake pathways to plant P. We grew plants singly or in pairs of the same or different genotypes (inoculated or not) in pots containing a small compartment with ³²P-labelled soil accessible to AM fungal hyphae and determined expression of orthophosphate (Pi) transporter genes involved in both AM and direct P uptake. Gigaspora margarita increased WT competitive effects on rmc. WT and rmc inoculated with Glomus intraradices both showed growth depressions, which were mitigated when G. margarita was present. Orthophosphate transporter gene expression and ³²P transfer showed that the AM pathway operated in single inoculated WT, but not in rmc. Effects of AM fungi on plant competition depended on the relative contributions of AM and direct pathways of P uptake. Glomus intraradices reduced the efficiency of direct uptake in both WT and rmc. The two-fungus combination showed that interactions between fungi are important in determining outcomes of plant competition.

• Publisher: Oxford, UK : Blackwell Publishing Ltd,Blackwell Publishing,Blackwell Publishing Ltd,Wiley Subscription Services, Inc
• Subject: Analysis of Variance / arbuscular mycorrhizal (AM) fungi / Arbuscular mycorrhizas / Biological competition / Biomass / Colony Count, Microbial / Competition / Cultivars / Defective mutant / direct and indirect effects / Fungi / Gene expression / Gene Expression Regulation, Plant / genes / genetics / genotype / Genotypes / Gigaspora margarita / Glomeromycota / Glomeromycota - growth & development / Glomeromycota - physiology / Glomus intraradices / growth & development / Hyphae / Inoculation / Lycopersicon esculentum / Lycopersicon esculentum - genetics / Lycopersicon esculentum - microbiology / metabolism / Microbial colonization / microbiology / model plants / Models, Biological / Music competitions / mutants / mycorrhiza-defective mutant / Mycorrhizae / Mycorrhizae - genetics / Mycorrhizae - physiology / mycorrhizal fungi / mycorrhizal symbiosis / Orthophosphate / orthophosphates / Phosphorus / phosphorus (P) uptake / Phosphorus - metabolism / physiology / Plant competition / Plant Epidermis / Plant Epidermis - genetics / Plant Epidermis - metabolism / Plant growth / Plant Proteins / Plant Proteins - genetics / Plant Proteins - metabolism / Plant roots / Plant Shoots / Plant Shoots - metabolism / Plants / Rhizophagus intraradices / soil / Soil fungi / Solanum lycopersicum / tomato mutant / Tomatoes / Uptake / vesicular arbuscular mycorrhizae