The Plant Cell: The phospholipid flippase ALA3 regulates pollen tube growth and guidance in Arabidopsis October 14,2022 Pollen tube guidance regulates the growth direction and ovule targeting of pollen tubes in pistils, which is crucial for the completion of sexual reproduction in flowering plants. The Arabidopsis (Arabidopsis thaliana) pollen-specific receptor kinase (PRK) family members PRK3 and PRK6 are specifically tip-localized and essential for pollen tube growth and guidance. However, the mechanisms controlling the polar localization of PRKs at the pollen tube tip are unclear. The Arabidopsis P4-ATPase ALA3 helps establish the polar localization of apical phosphatidylserine (PS) in pollen tubes. Professor Xiang yun and his research team from School of Life Sciences of Lanzhou University discovered that loss of ALA3 function caused pollen tube defects in growth and ovule targeting and significantly affected the polar localization pattern of PRK3 and PRK6. Both PRK3 and PRK6 contain two polybasic clusters in the intracellular juxtamembrane domain, and they bound to PS in vitro. PRK3 and PRK6 with polybasic cluster mutations showed reduced or abolished binding to PS and altered polar localization patterns, and they failed to effectively complement the pollen tube-related phenotypes of prk mutants. These results suggest that ALA3 influences the precise localization of PRK3, PRK6 and other PRKs by regulating the distribution of PS, which plays a key role in regulating pollen tube growth and guidance. Prev: The Plant Cell: Type one protein phosphatase regulates fixed-carbon starvation-induced autophagy in Arabidopsis Next: The Plant Cell: Receptor-like cytoplasmic kinases PBL34/35/36 are required for CLE peptide-mediated signaling to maintain shoot apical meristem and root apical meristem homeostasis in Arabidopsis