Inoculation with a ligninolytic basidiomycete, but not root symbiotic ascomycetes, positively affects growth of highbush blueberry (Ericaceae) grown in a pine litter substrate
Abstract
Ericoid mycorrhizal (ErM) fungi and other ericaceous root symbionts do not completely degrade lignin, therefore the presence of lignin in organic residues may present a barrier to nutrient uptake by ericaceous plants. Due to specialization of ErM and saprotrophic, lignin-degrading fungi in litter decomposition and nutrient mobilization, we hypothesized that the presence of both types of fungi may exert a synergism in the proximity of plant detritus, thereby increasing the growth of plants over those grown with only one type or no added fungi.
We tested this hypothesis by introducing ascomycetous ErM or root-endophytic fungi and the saprotrophic basidiomycete Agrocybe praecox to highbush blueberry (Vaccinium corymbosum) grown in a substrate of pine litter, bark and wood chips in a container experiment, and measured plant nutrient status and growth parameters over 30-months. We detected no synergistic or antagonistic interactions between the saprotrophic basidiomycete and the root-symbiotic ascomycetes.
Addition of lignin-degrading A. praecox but not ErM or endophytic symbionts positively impacted shoot growth, plant biomass, total P and N uptake from the substrate and precocity in fruit bearing despite widely acknowledged high saprotrophic abilities of the latter. We propose that lignin-degrading basidiomycetes are compatible with ericoid mycorrhizal roots and asymbiotically enhance plant growth via the release of N, P, and other nutrients from lignin-rich plant residues, thereby attenuating potential nutrient competition between plants and microbes as low quality litter decomposes.