Saprotrophic Responses by Ectomycorrhizal Fungi

小行星9318568米勒 许多研究已经检测到真菌（与树木根部共生的真菌）中的酶，这些酶可能在实验室研究中分解有机物质。其他研究表明，这些共生真菌在田间不具备这种分解能力，即使它们在土壤中的生长速度可能超过真正的腐食性真菌。这种明显的矛盾有几种可能性。这种共生关系可能会改变菌根真菌的行为，使酶的生产是不可能的。另一种可能性是，外生菌根真菌可能只能在宿主产生的糖没有足够数量的时候分解有机物质。在这种时候，菌根真菌的腐生性机制可能能够从有机基质中获得能量沿着所需的矿物元素。第三种可能性是，至少有一些关于实验室中酶活性的报告受到了批评，因为这些研究是在与这些真菌最有可能遇到的条件非常不同的条件下完成的。 我们建议研究外生菌根真菌的机制，可能使他们更好地与腐养真菌竞争。我们将通过在实验室中使用专门设计的根室进行实验来实现这一点，这些根室允许真菌的一部分从根和生根基质中分离出来，同时仍然与树共生。这种方法将使我们能够调查腐营养reposes外生菌根真菌在一个水平，迄今尚未实现。 ***

9318568 Miller Many studies have detected enzymes in fungi (fungi that are symbiotically associated with the roots of trees) that may decompose organic matter in laboratory studies. Other studies imply that these symbiotic fungi are not capable of such decomposition in the field even though they may outgrow true saprotrophic fungi in the soil. Several possibilities exist for this apparent contradiction. The symbiotic association may alter the behavior of mycorrhizal fungi so that enzyme production is not possible. Another possibility is that ectomycorrhizal fungi may only be able to decompose organic matter during times when sugars produced by their host are not being produced in sufficient quantities. At such times, the saprotrophic machinery of mycorrhizal fungi may be able to obtain energy along with required mineral elements from organic substrates. A third possibility is that at least some reports of enzymatic activity in the laboratory are subject to criticism because the research has been accomplished under conditions that are very different from what would most likely be encountered by these fungi. We propose to examine the mechanisms of ectomycorrhizal fungi that may allow them to better compete with saprotrophic fungi. We will accomplish this by conducting experiments in the laboratory using specially designed root chambers that allow growth and manipulation of a portion of the fungus separate from the roots and rooting substrate while still in symbiosis with the tree. This approach will allow us to investigate the saprotrophic reposes by ectomycorrhizal fungi at a level that heretofore has not been achieved. ***