Dauphin A, De Ruijter N C A, Emons A M C, Legué V
Unité Mixte de Recherche UMR INRA-UHP 1136 Interactions Arbres/Micro-Organismes, Université Nancy I, Faculté des Sciences, BP 239, 54506 Vandoeuvre Cedex, France.
Plant Biol (Stuttg). 2006 Mar;8(2):204-11. doi: 10.1055/s-2006-923767.
The fungus Pisolithus microcarpus establishes an ectomycorrhiza with Eucalyptus globulus. This symbiosis involves a fungal synthesis and secretion of hypaphorine, an indolic compound. Previous studies have shown that hypaphorine induces an alteration in the actin cytoskeleton of elongating root hairs and inhibits hair elongation. Using an alternative approved method, we analyzed the effects of hypaphorine on the E. globulus root hair cyto-architecture and actin configuration in more detail and provide new results. One mM hypaphorine stops root hair elongation within 20 min, and changes the hair cyto-architecture. Semi-quantitative analysis of the actin cytoskeleton before and after treatment with hypaphorine shows that hypaphorine induces a shift from fine F-actin to F-actin bundles in the sub-apex of the hair, which occurs first in the mid-plane of the cell. This creates a sub-apical cell centre free of filamentous actin, an actin configuration that differs from that during developmental growth arrest. The mechanism of action of hypaphorine is discussed.
微小皮伞菌与蓝桉形成外生菌根。这种共生关系涉及真菌合成并分泌一种吲哚类化合物——对羟基苯甘氨酸。先前的研究表明，对羟基苯甘氨酸会导致伸长的根毛肌动蛋白细胞骨架发生改变，并抑制根毛伸长。我们采用另一种经批准的方法，更详细地分析了对羟基苯甘氨酸对蓝桉根毛细胞结构和肌动蛋白构型的影响，并提供了新的结果。1 mM的对羟基苯甘氨酸在20分钟内会阻止根毛伸长，并改变根毛的细胞结构。对对羟基苯甘氨酸处理前后的肌动蛋白细胞骨架进行半定量分析表明，对羟基苯甘氨酸会诱导根毛顶端下区域的细F-肌动蛋白转变为F-肌动蛋白束，这种转变首先发生在细胞的中平面。这会在顶端下区域形成一个没有丝状肌动蛋白的细胞中心，这种肌动蛋白构型与发育性生长停滞期间的不同。本文还讨论了对羟基苯甘氨酸的作用机制。
