Competitive interactions of ectomycorrhizal mycobionts under field conditions

Abstract

A rapid field method to evaluate the competitive performance of selected ectomycorrhizal isolates is presented. Ectomycorrhizal jack pine seedlings and noninoculated controls produced in growth pouches were outplanted in diverse stations 1 month after inoculation. Photographs taken prior to outplanting and at the time of excavation permitted comparative observations of mycorrhizal development along each lateral root of individual seedlings. Nonmycorrhizal control seedlings showed 0, 20, 20, and 76% mycorrhizal development at the sterilized denuded, unsterilized denuded, burned, and undisturbed jack pine stand stations, respectively. To evaluate the postplanting performance of each isolate tested, an index of colonization and an index of competition were established. Laccaria bicolor was the best colonizer at all stations except the undisturbed jack pine stand, where Rhizopogon rubescens was the best colonizer and also the most competitive. Pisolithus tinctorius was not competitive with the indigenous mycota at the burned or the undisturbed jack pine stand stations.

Survival after outplanting of the ectomycorrhizal fungus Laccaria bicolor S238N inoculated on Douglas fir (Pseudotsuga menziesii (Mirb.) Franco) cuttings

“…Genotyping (table IV) showed that these Laccaria-like mycorrhizas or undetermined mycorrhizas were mainly formed by a new ribotype (ribotype 1/3) coming from the plantation site. Its ITS rDNA pattern was different from the several hundreds patterns recorded in the INRA MycoMol database or in other ITS databases [15,20].…”

“…Despite the imprecision of such methods, some results are available in the litterature. McAfee and Fortin [20] observed on Pinus banksiana seedlings that the inoculated fungus, Laccaria bicolor, colonised 55% of the short roots after two months in the field. Danielson and Visser [7] found that Laccaria proxima and Thelephora terrestris were completely superseded by naturally occurring fungi one year after transplantation.…”

Isozyme variation and somatic incompatibility in populations of the ectomycorrhizal fungus Suillus collinitus

“…Intraspecific genetic variation shown in this study could be used to screen genetically difFerent isolates before use in mycorrhizal trials. Indeed, genetic differences might reflect intraspecific variations in ectomycorrhizal aggressivity (Perry, Molina & Amaranthus, 1987;Sen, 1990fl, b;' VV' ong & Fortin, 1990;Albrecht, Burgess & Lapeyrie, 1994;Rosado, Kropp & Piche, 1994), the ability to improve mineral nutrition and growth of young host trees (Harley & Smith, 1983;Le Tacon, 1985;Harley, 1989;Lamhamedi et a/., 1990;Sen, \990b), the protection of root systems against phytopathogenic fungi (Marx, 1969;Marx, 1972;Perrin, 1985) and ability to compete with other ectomycorrhizal symbionts (McAfee & Fortin, 1986). This work shows that isozyme analysis combined with somatic incompatibility testing are efficient tools with which to study the population biology of ectomycorrhizal fungi found under forest trees.…”

Evidence of species interactions within an ectomycorrhizal fungal community

“…in the outplanted soil, while other species are quite competitive and persist for years (Lamb, 1979;Fleming, 1985;McAfee & Fortin, 1986;Villeneuve et al, 1991;Selosse et al, 1998;Wu et al, 1999). Persistence may be related to the ability of a species to exclude others from colonizing roots (Fleming, 1985;Mamoun & Olivier, 1993a,b;Olivier & Mamoun, 1994).…”