叢枝菌根對寄主植物磷吸收之影響

The Effect of Arbuscular Mycorrhizae on Phosphate Uptake of Host Plants

具有叢枝菌根的植物之磷吸收速率常較無菌根者為高，原因是根外菌絲能直接吸收土壤中之可溶性磷，並且擴大吸收之範圍。雖然土壞中之磷肥過高可能會抑制菌根菌之感染，但只要植物已形成菌根後，土壤中之高磷含量並不一定會使根外菌絲之磷吸收速率下降。根外菌絲所吸收的磷可在菌絲內形成聚合磷酸鹽顆粒，聚合磷酸鹽顆粒藉由菌絲內部之細胞質流運至叢枝體，之後則以解離之方式與寄主光合產物在中間介面處以反向運輸進入根細胞內。

Due to the low mobility of phosphate in soil a depletion zone of phosphate evolves in the rhizosphere of soil-grown roots. Plants with arbuscular mycorrhizae (AM) frequently exhibit increased inflow of phosphate in comparison to non-mycorrhiza controls. This response is most often attributed to a direct uptake of phosphate and the extension of the phosphate uptake zone by external hyphae of AM fungi. Colonization of roots by AM fungi is often suppressed by high levels of soluble phosphate. However, the high concentration of phosphate may not cause low inflow of phosphate by external hyphae if the colonized roots were formed. Phosphate is taken up and probably translocated as polyphosphate granules by protoplasmic streaming before being hydrolyzed in the arbuscules prior to photosynthate antiport across the host-fungus interface.