质子流(H+)作为丛枝菌根(AM)真菌芽管菌丝发育的标签
2008年4月，Feijá等科学家使用“非损伤微测技术(the ion-selective vibrating probe system)”研究了芽管菌丝发育时期菌丝中的H+流，发现胞外的pH在宿主和真菌间的离子交换和AM真菌生长中起到重要作用，菌丝的H+流振荡与芽管菌丝的生长存在相互关系，AM菌丝的H+流和生长被宿主根系分泌物(RE)所调控。菌丝H+流空间和时间的转变被营养利用状况所调控，也有可能被pH信号所诱导。
此项工作对于认识真菌的生长发育以及响应外源物质的机理提供了全新的思路，也揭示了菌丝对P和Suc利用的细胞生物学生理学机制。
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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