Bronkhorst Jochem, Kots Kiki, de Jong Djanick, Kasteel Michiel, van Boxmeer Thomas, Joemmanbaks Tanweer, Govers Francine, van der Gucht Jasper, Ketelaar Tijs, Sprakel Joris
Physical Chemistry and Soft Matter, Wageningen University & Research, Stippeneng 4, 6708 WE Wageningen, Netherlands.
Laboratory of Phytopathology, Wageningen University & Research, Droevendaalsesteeg 1, 6708 PB Wageningen, Netherlands.
Sci Adv. 2022 Jun 10;8(23):eabo0875. doi: 10.1126/sciadv.abo0875.
Filamentous plant pathogens apply mechanical forces to pierce their hosts surface and penetrate its tissues. Devastating pathogens harness a specialized form of invasive tip growth to slice through the plant surface, wielding their hypha as a microscopic knife. Slicing requires a sharp hyphal tip that is not blunted at the site of the mechanical interaction. How tip shape is controlled, however, is unknown. We uncover an actin-based mechanostat in that controls tip sharpness during penetration. Mechanical stimulation of the hypha leads to the emergence of an aster-like actin configuration, which shows fast, local, and quantitative feedback to the local stress. We evidence that this functions as an adaptive mechanical scaffold that sharpens the invasive weapon and prevents it from blunting. The hyphal tip mechanostat enables the efficient conversion of turgor into localized invasive pressures that are required to achieve host penetration.
丝状植物病原体施加机械力以刺穿宿主表面并穿透其组织。具有破坏性的病原体利用一种特殊形式的侵入性顶端生长来切开植物表面，将它们的菌丝当作一把微观层面的刀来使用。切割需要一个尖锐的菌丝顶端，该顶端在机械相互作用的部位不会变钝。然而，顶端形状是如何被控制的尚不清楚。我们发现了一种基于肌动蛋白的机械平衡机制，它在穿透过程中控制顶端的尖锐度。对菌丝的机械刺激会导致出现一种星状肌动蛋白构型，该构型对局部应力表现出快速、局部和定量的反馈。我们证明，这起到了一种适应性机械支架的作用，使侵入性武器变锋利并防止其变钝。菌丝顶端机械平衡机制能够将膨压有效地转化为实现宿主穿透所需的局部侵入压力。
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