質子流(H+)作為叢枝菌根(AM)真菌芽管菌絲發育的標簽
2008年4月，Feijá等科學家使用“非損傷微測技術(the ion-selective vibrating probe system)”研究了芽管菌絲發育時期菌絲中的H+流，發現胞外的pH在宿主和真菌間的離子交換和AM真菌生長中起到重要作用，菌絲的H+流振蕩與芽管菌絲的生長存在相互關系，AM菌絲的H+流和生長被宿主根系分泌物(RE)所調控。菌絲H+流空間和時間的轉變被營養利用狀況所調控，也有可能被pH信號所誘導。
此項工作對于認識真菌的生長發育以及響應外源物質的機理提供了全新的思路，也揭示了菌絲對P和Suc利用的細胞生物學生理學機制。
arbuscular mycorrhiza • Gigaspora margarita • H+-specific vibrating probe • pH signatures • presymbiosis
ABSTRACT
• Ion dynamics are important for cell nutrition and growth in fungi and plants. Here, the focus is on the relationship between the hyphal H+ fluxes and the control of presymbiotic growth and host recognition by arbuscular mycorrhizal (AM) fungi.
• Fluxes of H+ around azygopores and along lateral hyphae of Gigaspora margarita during presymbiotic growth, and their regulation by phosphate (P) and sucrose (Suc), were analyzed with an H+-specific vibrating probe. Changes in hyphal H+ fluxes were followed after induction by root exudates (RE) or by the presence Trifolium repens roots.
• Differential sensitivity to P-type ATPase inhibitors (orthovanadate or erythrosin B) suggests an asymmetric distribution or activation of H+-pump isoforms along the hyphae of the AM fungi. Concentration of P and Suc affected the hyphal H+ fluxes and growth rate. However, further increases in H+ efflux and growth rate were observed when the fungus was growing close to clover roots or pretreated with RE.
• The H+ flux data correlate with those from polarized hyphal growth analyses, suggesting that spatial and temporal alterations of the hyphal H+fluxes are regulated by nutrient availability and might underlie a pH signaling elicitation by host RE during the early events of the AM symbiosis.
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