Arabidopsis actin-depolymerizing factor10 depolymerizes apical actin filaments to facilitate pollen tube turning in response to female attractant

Peptide/receptor-like kinase-mediated signaling plays a pivotal role in male-female interactions, particularly in guiding the growth of pollen tubes, which is essential for fertilization in flowering plants. However, the downstream cellular events within the pollen tube guidance signaling network remain largely unexplored. In this study, actin dynamics in pollen tubes growing semi-in vitro were directly visualized, and it was discovered that AtLURE1s-induced pollen tube growth guidance is intricately regulated by actin assembly and disassembly. The observations revealed that apical actin filaments undergo a process of rapid depolymerization and repolymerization at the leading side, which in turn facilitates the reconstruction of the apical actin structure, enabling the pollen tube to grow in a new direction. Notably, it was observed that actin depolymerization and subsequent repolymerization occur on the leading side before any morphological changes in the pollen tube. Furthermore, it was found that the loss of function of ADF10 results in the accumulation of apical actin filaments, altering the turning behavior of the pollen tube. These findings suggest that rapid actin depolymerization at the leading side and the subsequent reconstruction of the apical structure occur early and are crucial for successful pollen tube turning.