Solubilization of Insoluble Inorganic Phosphate by Hyphal Exudates of Arbuscular Mycorrhizal Fungi
Solubilization of Insoluble Inorganic Phosphate by Hyphal Exudates of Arbuscular Mycorrhizal Fungi
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DOI：
10.1080/01904160600564428
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发表时间：
2006-05
影响因子：
2.1
通讯作者：
K. Tawaraya;M. Naito;T. Wagatsuma
中科院分区：
文献类型：
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作者：
K. Tawaraya;M. Naito;T. Wagatsuma
丛枝菌根（AM）真菌增加植物对磷酸盐(P)的吸收被认为主要依赖于外部菌丝进入土壤的延伸。另一方面，一些外生菌根真菌的菌丝释放有机酸到土壤中，并溶解不溶性无机磷。本研究收集了AM真菌在分区盆栽中的菌丝渗出液，并阐明了其溶解不溶性无机磷的能力。用AM真菌、margarita Gigaspora和Glomus etunicatum分别接种韭菜（Allium cepa）培养幼苗。对照盆不接种。莫来石陶瓷管埋于每个隔间的土壤中，并收集土壤溶液。土壤溶液的阴离子部分与磷酸铁（4mg FePO4在1ml 0.4醋酸缓冲液中）孵育。测定溶解磷。接种玛格丽塔菌（G. margarita）和灰桐菌（G. etunicatum）的植株，AM定殖率分别为86%和54%。在菌丝室土壤中埋设的莫来石陶瓷管表面观察到外菌丝的粘附。这两种真菌的定植均增加了茎部对磷的吸收和生长。从两种真菌菌丝室收集的土壤溶液比未接种的植物溶解更多的磷。由此可见，菌丝渗出物有助于增加定殖植株对磷的吸收。
ABSTRACT Increased phosphate (P) uptake in plants by arbuscular mycorrhizal (AM) fungi is thought to depend mainly on the extension of external hyphae into soil. On the other hand, it is known that the hyphae of some kinds of ectomycorrhizal fungi release organic acids into soil and that they dissolve the insoluble inorganic P. This study collected hyphal exudates of AM fungi within compartmentalized pot culture and clarified their ability to solubilize insoluble inorganic P. Sterilized Andisol was packed in pots that were separated into root and hyphal compartments with a nylon net of 30 μm pore size. Seedlings of Allium cepa inoculated with AM fungi, Gigaspora margarita, or Glomus etunicatum were grown. Control pots were not inoculated. Mullite ceramic tubes were buried in the soil of each compartment and soil solution was collected. The anionic fraction of the soil solution was incubated with iron phosphate (4 mg FePO4 in 1 mL of 0.4 acetate buffer). Solubilized P was measured. The AM colonization of plants inoculated with G. margarita and G. etunicatum was 86% and 54%, respectively. Adhesion of external hyphae was observed on the surface of the mullite ceramic tubes buried in soil of the hyphal compartment. Colonization of both fungi increased shoot P uptake and growth. Soil solution collected from the hyphal compartments of both fungi solubilized more P than did that from uninoculated plants. It is suggested that hyphal exudates can contribute to increased P uptake of colonized plants.