Rúa Megan A, Moore Becky, Hergott Nicole, Van Lily, Jackson Colin R, Hoeksema Jason D
Department of Biology, University of Mississippi, Oxford, MS 38677, USA.
Department of Ecology and Evolutionary Biology, University of Tennessee, Knoxville, TN 37966, USA.
J Fungi (Basel). 2015 Aug 28;1(2):185-210. doi: 10.3390/jof1020185.
Extracellular enzymes degrade macromolecules into soluble substrates and are important for nutrient cycling in soils, where microorganisms, such as ectomycorrhizal (ECM) fungi, produce these enzymes to obtain nutrients. Ecotones between forests and fields represent intriguing arenas for examining the effect of the environment on ECM community structure and enzyme activity because tree maturity, ECM composition, and environmental variables may all be changing simultaneously. We studied the composition and enzymatic activity of ECM associated with loblolly pine (Pinus taeda) across an ecotone between a forest where P. taeda is established and an old field where P. taeda saplings had been growing for <5 years. ECM community and environmental characteristics influenced enzyme activity in the field, indicating that controls on enzyme activity may be intricately linked to the ECM community, but this was not true in the forest. Members of the Russulaceae were associated with increased phenol oxidase activity and decreased peroxidase activity in the field. Members of the Atheliaceae were particularly susceptible to changes in their abiotic environment, but this did not mediate differences in enzyme activity. These results emphasize the complex nature of factors that dictate the distribution of ECM and activity of their enzymes across a habitat boundary.
胞外酶将大分子降解为可溶性底物，对土壤中的养分循环很重要，在土壤中，诸如外生菌根（ECM）真菌等微生物会产生这些酶来获取养分。森林与田野之间的生态交错带是研究环境对外生菌根群落结构和酶活性影响的有趣场所，因为树木成熟度、外生菌根组成和环境变量可能会同时发生变化。我们研究了在一个已种植火炬松的森林与一个火炬松树苗生长不到5年的旧耕地之间的生态交错带上，与火炬松（Pinus taeda）相关的外生菌根的组成和酶活性。外生菌根群落和环境特征影响了田间的酶活性，这表明对酶活性的控制可能与外生菌根群落密切相关，但在森林中并非如此。红菇科成员与田间酚氧化酶活性增加和过氧化物酶活性降低有关。无柄盘菌科成员对其非生物环境的变化特别敏感，但这并未介导酶活性的差异。这些结果强调了决定外生菌根分布及其酶在栖息地边界上活性的因素的复杂性。
