Journal
MOLECULAR PLANT
Volume 8, Issue 12, Pages 1694-1709Publisher
CELL PRESS
DOI: 10.1016/j.molp.2015.09.013
Keywords
pollen tube; actin; actin polymerization; profilin; formin
Categories
Funding
- Ministry of Science and Technology of China [2013CB945100, 2011CB944600]
- National Natural Science Foundation of China [31125004, 31121065, 31270223]
- Tsinghua-Peking Joint Center for Life Sciences
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Pollen tube growth is an essential step during flowering plant reproduction, whose growth depends on a population of dynamic apical actin filaments. Apical actin filaments were thought to be involved in the regulation of vesicle fusion and targeting in the pollen tube. However, the molecular mechanisms that regulate the construction of apical actin structures in the pollen tube remain largely unclear. Here, we identify profilin as an important player in the regulation of actin polymerization at the apical membrane in the pollen tube. Downregulation of profilin decreased the amount of filamentous actin and induced disorganization of apical actin filaments, and reduced tip-directed vesicle transport and accumulation in the pollen tube. Direct visualization of actin dynamics revealed that the elongation of actin filaments originating at the apical membrane decreased in profilin mutant pollen tubes. Mutant profilin that is defective in binding poly-L-proline only partially rescues the actin polymerization defect in profilin mutant pollen tubes, although it fully rescues the actin turnover phenotype. We propose that profilin controls the construction of actin structures at the pollen tube tip, presumably by favoring formin-mediated actin polymerization at the apical membrane.
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