Phosphatase activity of extra-radical arbuscular mycorrhizal hyphae: A review
Phosphatase activity of extra-radical arbuscular mycorrhizal hyphae: A review
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DOI：
10.1023/a:1026582207192
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发表时间：
2000-01-01
期刊：
影响因子：
4.9
通讯作者：
Vosatka, M
中科院分区：
文献类型：
--
作者：
Joner, EJ;van Aarle, IM;Vosatka, M
丛枝菌根（AM）真菌的磷酸酶活性在三个相当不同的领域引起了人们的注意：已经在根内菌丝中研究了具有确定的代谢功能的细胞内酶，碱性磷酸酶的组织化学染色作为根内和根外测量的真菌活性的指示剂，以及与有机P（P（o））化合物矿化相关的胞外活性，其可增强菌根对土壤中重要营养库的利用。这篇评论侧重于后者的主题，强调根外菌丝体（ERM），而它借鉴了有关其他生物的磷酸酶的大量材料中的选定数据。我们的结论是，碱性磷酸酶的组织化学染色是一种敏感和合适的方法，用于监测ERM遇到的不利条件的影响，无论是作为一个共生功能实体在土壤中，并在体外不修改干扰土壤或其他固体基质。此外，胞外酶对AM植物磷营养的定量重要性估计是微不足道的。这是从AM真菌胞外菌丝对土壤中总磷酸酶活性的低定量贡献得出的结论，并从估计哪些过程可能是有机磷矿化的速率限制。前者的最大值大约为百分之几。对于后者，P（o）的增溶作用似乎比P（o）的水解作用对AM真菌和植物利用P（o）更为重要，因为土壤内源磷酸酶活性和其他土壤生物的磷酸酶都是普遍存在和丰富的。我们对菌根磷酸酶的讨论支持这样的观点，即根和微生物的胞外磷酸酶在很大程度上偶然释放到土壤中，并且来源从其活性中获益有限。
Phosphatase activity of arbuscular mycorrhizal (AM) fungi has attracted attention in three fairly distinct domains: intracellular enzymes with defined metabolic functions that have been studied in intraradical hyphae, histochemical staining of alkaline phosphatase as an indicator of fungal activity measured both intra- and extraradically, and extracellular activity related to mineralization of organic P (P(o)) compounds that may enhance mycorrhizal utilization of an important nutrient pool in soil. This review focuses on the latter subjects with emphasis on extraradical mycelium (ERM), while it draws on selected data from the vast material available concerning phosphatases of other organisms. We conclude that histochemical staining of alkaline phosphatase is a sensitive and suitable method for monitoring the effect of adverse conditions encountered by ERM both as a symbiotically functional entity in soil, and in vitro without modifying interference of soil or other solid substrates. Furthermore, the quantitative importance of extracellular enzymes for P nutrition of AM plants is estimated to be insignificant. This is concluded from the low quantitative contribution extracellular hyphae of AM fungi give to the total phosphatase activity in soil, and from estimations of which processes that may be rate limiting in organic P mineralization. Maximum values for the former is in the order of a few percent. As for the latter, solubilization of P(o) seems to be far more important than P(o) hydrolysis for utilization of P(o) by AM fungi and plants, as both endogenous soil phosphatase activity and phosphatases of other soil organisms are ubiquitous and abundant. Our discussion of mycorrhizal phosphatases supports the view that extracellular phosphatases of roots and micro-organisms are to a large extent released incidentally into soil, and that the source has limited benefit from its activity.