New
Phytologist 166(2): 601 (May 2005)
Does the
presence of arbuscular mycorrhizal fungi influence growth and nutrient uptake
of a wild-type tomato cultivar
and a mycorrhiza-defective mutant, cultivated
with roots sharing the same soil volume?
Elke Neumann and
Eckhard George
Summary
• We investigated the growth and nutrient uptake of the Lycopersicon esculentum symbiosis mycorrhiza-defective plant mutant rmc, challenged with arbuscular mycorrhiza (AM) fungal propagules, in the presence or absence of roots of the commercial wild-type tomato cv. Golden Queen (GQ).
• Two plants shared the middle (combi) compartment of a horizontal three-compartment split-root pot with one part of their root system; the other part was grown separately in an outer (solo) pot. Combinations of rmc and GQ plants were grown together in soil that was either mycorrhiza-free (–M) or prepared with AM fungal inoculum (+M).
• Surface colonization of rmc roots was strongly increased in the presence of (+M) GQ roots. AM fungal inoculation increased phosphorus uptake of GQ plants, but decreased growth and P uptake of rmc plants. Growth and P uptake of (+M) GQ plants were reduced when plants were grown in combination with rmc rather than another GQ plant.
• AM fungi in the (combi) compartment may have preferentially formed hyphae spreading infection rather than functioning in P uptake in (+M) GQ plants grown in combination with rmc. Surface colonization of (+M) rmc roots, in the presence of GQ roots, was probably established at the expense of carbohydrates from associated GQ plants. Possible reasons for a decreased P uptake of rmc plants in response to AM fungal inoculation are proposed.