Annexins from plants and animals have highly similar protein function and structure, with core domains composed of four homologous repeats of approximately 60–70 amino acids that contain a conserved Ca2+- and membrane-binding motif. In recent years, annexins from many different plants have been isolated, and their functions have been studied. As with annexins in animals,Vinorelbine those in plants have the conserved function of the protein family and participate in many significant physiological activities, such as the cell cycle, pollen and seed germination, tuber development of cassava, cotton fiber elongation, petunia petal senescence, strawberry fruit ripening and gall ontogeny, primary root growth and lateral root formation, vascular development and cork formation. Most of these events are linked to Ca2+ signaling and membrane function. In addition, certain plant annexins can also function in environmental stimuli. There are eight annexin genes with deduced amino acid sequence identities varying from 29% to 83% in the Arabidopsis genome. AnnAt1 and AnnAt4 participate in osmotic stress and ABA signaling in a Ca2+-dependent manner, which could implicate them in exocytosis or cell cycle control. Some abiotic stress stimuli, such as light, gravity,Glyburide phosphate starvation, metal stress, cold, drought and oxidation, can alter the expression and abundance of plant annexins. Interestingly, Blachbourn et al. demonstrated the presence of lily annexins at the apex of the pollen tube via an immunofluorescence assay, and these annexins also bound to vesicles in the pollen tube in a Ca2+-dependent manner. These results suggest that annexin may function as an important ‘‘linker‘‘ between the membrane, actin cytoskeleton and Ca2+ in the polarized growth of the pollen tube. However, this hypothesis has not been conclusively demonstrated in the research on the involvement of annexin family proteins in the polarized growth of pollen tubes. Many reports have shown that membrane-related processes, such as membrane trafficking, fusion and exocytosis, are highly active throughout pollen development and necessary for normal pollen development. It has been demonstrated that membrane trafficking and deformation by the ER and Golgi occur as early as the uninucleate late microspore stage.