The initiation of intracellular host cell colonization by symbiotic rhizobia in Medicago truncatula requires repolarization of root hairs, which includes the re-arrangement of cytoskeletal filaments. The molecular players governing microtubule (MT) re-organization during rhizobial infections remain to be discovered. Here, we identified M. truncatula DREPP, a member of the microtubule binding DREPP/PCaP protein family and investigated its functions during rhizobial infections. We show that rhizobial colonization of drepp mutant roots as well as transgenic roots over-expressing DREPP is impaired. DREPP re-localizes into symbiosis-specific membrane nanodomains in a stimulus-dependent manner. This subcellular segregation coincides with DREPP-dependent MT fragmentation and a partial loss of the ability to re-organize the MT cytoskeleton in response to rhizobia, which might rely on an interaction between DREPP and the MT organizing protein SPIRAL2 (SPR2). Taken together, our results reveal that establishment of symbiotic associations in M. truncatula require DREPP in order to regulate MT reorganization during initial root hair responses to rhizobia.

截短苜蓿中由共生根瘤菌引起的细胞内宿主细胞定殖的开始要求根毛重新极化，这包括细胞骨架细丝的重新排列。根瘤菌感染期间控制微管（MT）重组的分子参与者仍有待发现。在这里，我们确定了M. truncatula DREPP，一种结合DREPP / PCaP蛋白的微管家族，并研究了其在根瘤菌感染期间的功能。我们表明，drepp突变根以及过表达DREPP的转基因根的根瘤菌定植受到损害。DREPP以刺激依赖的方式重新定位到共生特异性膜纳米域。这种亚细胞分离与DREPP依赖性MT片段化和部分根除根​​瘤菌对MT细胞骨架的重新组织能力的丧失相符，这可能依赖于DREPP和MT组织蛋白SPIRAL2（SPR2）之间的相互作用。两者合计，我们的结果表明，在M. truncatula中建立共生联系需要DREPP，以便在根发对根瘤菌的最初反应期间调节MT重组。