The Microtubule End Binding Protein Mal3 Is Essential for the Dynamic Assembly of Microtubules during Growth and Pathogenesis.

Cytoskeletal microtubules (MTs) play crucial roles in many aspects of life processes in eukaryotic organisms. They dynamically assemble physiologically important MT arrays under different cell conditions. Currently, aspects of MT assembly underlying the development and pathogenesis of the model plant pathogenic fungus () are unclear. In this study, we characterized the MT plus end binding protein MoMal3 in . We found that knockout of results in defects in hyphal polar growth, appressorium-mediated host penetration and nucleus division. Using high-resolution live-cell imaging, we further found that the mutant assembled a rigid MT in parallel with the MT during hyphal polar growth, the cage-like network in the appressorium and the stick-like spindle in nuclear division. These aberrant MT organization patterns in the mutant impaired actin-based cell growth and host infection. Taken together, these findings showed that relies on MoMal3 to assemble elaborate MT arrays for growth and infection. The results also revealed the assembly mode of MTs in , indicating that MTs are pivotal for growth and host infection and may be new targets for devastating fungus control.