Mycorrhizal symbiosis promotes host-plant zinc nutrition.

摘要

Mycorrhiza are ubiquitous soil fungi forming symbiotic association in most of the terrestrial plant species and contributing towards host plant nutrition of slowly diffusing nutrient ions such as PO₄, Zn, Cu and B. Mycorrhizal fungi improve the host plant zinc nutritional status as a result of hyphal transport of Zn, biochemical changes in the rhizosphere and physiological modifications in the host plant. Since Zn is immobile in soil solution, the external mycelium of the mycorrhizal fungi facilitates the transport of Zn from the soil to the host plant. Biochemical changes such as acidification of rhizosphere and associated solubilization of residual Zn (fixed form) to exchangeable or organically bound Zn (soluble Zn) improve the availability of Zn in mycorrhizal soil. Further, mycorrhizal symbiosis assists the host plants to produce anti-oxidants that quench the reactive oxygen species and often protect against Zn deficiency. In this review, mechanisms involved in mycorrhiza-aided Zn nutritional status of host plants are summarized.