質(zhì)子流(H+)作為叢枝菌根(AM)真菌芽管菌絲發(fā)育的標簽
2008年4月，F(xiàn)eijá等科學家使用“非損傷微測技術(shù)(the ion-selective vibrating probe system)”研究了芽管菌絲發(fā)育時期菌絲中的H+流，發(fā)現(xiàn)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(guān)系，AM菌絲的H+流和生長被宿主根系分泌物(RE)所調(diào)控。菌絲H+流空間和時間的轉(zhuǎn)變被營養(yǎng)利用狀況所調(diào)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(fā)育以及響應外源物質(zhì)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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