The rice blast fungus Magnaporthe oryzae uses a pressurized infection cell called an appressorium to drive a rigid penetration peg through the leaf cuticle. The vast internal pressure of an appressorium is very challenging to investigate, leaving our understanding of the cellular mechanics of plant infection incomplete. Here, using fluorescence lifetime imaging of a membrane-targeting molecular mechanoprobe, we quantify changes in membrane tension in M. oryzae. We show that extreme pressure in the appressorium leads to large-scale spatial heterogeneities in membrane mechanics, much greater than those observed in any cell type previously. By contrast, non-pathogenic melanin-deficient mutants, exhibit low spatially homogeneous membrane tension. The sensor kinase ∆sln1 mutant displays significantly higher membrane tension during inflation of the appressorium, providing evidence that Sln1 controls turgor throughout plant infection. This non-invasive, live cell imaging technique therefore provides new insight into the enormous invasive forces deployed by pathogenic fungi to invade their hosts, offering the potential for new disease intervention strategies.

稻瘟病菌Magnaporthe oryzae使用一种称为附着细胞的加压感染细胞来驱动刚性穿透钉穿过叶角质层。附着胞巨大的内部压力非常难以研究，这使得我们对植物感染的细胞机制的理解不完整。在这里，利用膜靶向分子机械探针的荧光寿命成像，我们量化了米霉中膜张力的变化。我们发现，附着细胞中的极端压力会导致膜力学的大规模空间异质性，比之前在任何细胞类型中观察到的都要大得多。相比之下，非致病性黑色素缺陷突变体表现出低空间均匀膜张力。传感器激酶 Δ sln1突变体在附着胞膨胀期间表现出显着更高的膜张力，这提供了 Sln1 在整个植物感染过程中控制膨压的证据。因此，这种非侵入性活细胞成像技术提供了对病原真菌侵入宿主的巨大侵袭力的新见解，为新的疾病干预策略提供了潜力。