The life cycle of flowering plants starts when a zygote is formed following a double fertilization event.To achieve fertilization,sperm cells are delivered to the female gametes within the embryo sac by the tip-growin...The life cycle of flowering plants starts when a zygote is formed following a double fertilization event.To achieve fertilization,sperm cells are delivered to the female gametes within the embryo sac by the tip-growing pollen tube.The fast-growing pollen tube is characterized and regulated by abundant transport vesicles responsible for both exocytosis and endocytosis in the tip region.Visualization of these tip-vesicles has been challenging owing to their small size,high dynamics,and complexity.In this study,we illustrated the three-dimensional(3D)ultrastructure of tip-vesicles in growing pollen tubes of lily,tobacco,and Arabidopsis.Five major types of tip-vesicles,including secretory vesicles(SVs),electron-dense vesicles(DVs),clathrin-coated vesicles(CCVs),mini vesicles(MVs),and extracellular vesicles(EVs),can be distinguished using room-temperature electron tomography(RT-ET)based on their ultrastructural features.We also demonstrated the extensive distribution of tubular endoplasmic reticulum(ER)structures at the apex of growing pollen tubes and vesicles budding from the tip-localized ER.Cryo-ET further revealed the tip-localized tubular ER with budding coat protein complex II(COPII)vesicles.Our study thus offered a structural basis for a deeper comprehension of vesicular trafficking in the tip growth of the pollen tube,aiding future research on vesicle-mediated membrane trafficking in polarized cell growth.展开更多
基金supported by the Research Grants Council of Hong Kong(CRS_CUHK405/23,AoE/M-402/25-N,AoE/M-05/12,CUHK14106823,C4033-19E,C4002-20W,C4002-21EF,C2009-19G,C2003-22WF,R4005-18,C4014-23G,G-CUHK409/23 and Senior Research Fellow Scheme(SRFS2122-4S01))the Chinese University of Hong Kong(CUHK)Research Committee,and Science Faculty。
文摘The life cycle of flowering plants starts when a zygote is formed following a double fertilization event.To achieve fertilization,sperm cells are delivered to the female gametes within the embryo sac by the tip-growing pollen tube.The fast-growing pollen tube is characterized and regulated by abundant transport vesicles responsible for both exocytosis and endocytosis in the tip region.Visualization of these tip-vesicles has been challenging owing to their small size,high dynamics,and complexity.In this study,we illustrated the three-dimensional(3D)ultrastructure of tip-vesicles in growing pollen tubes of lily,tobacco,and Arabidopsis.Five major types of tip-vesicles,including secretory vesicles(SVs),electron-dense vesicles(DVs),clathrin-coated vesicles(CCVs),mini vesicles(MVs),and extracellular vesicles(EVs),can be distinguished using room-temperature electron tomography(RT-ET)based on their ultrastructural features.We also demonstrated the extensive distribution of tubular endoplasmic reticulum(ER)structures at the apex of growing pollen tubes and vesicles budding from the tip-localized ER.Cryo-ET further revealed the tip-localized tubular ER with budding coat protein complex II(COPII)vesicles.Our study thus offered a structural basis for a deeper comprehension of vesicular trafficking in the tip growth of the pollen tube,aiding future research on vesicle-mediated membrane trafficking in polarized cell growth.
