The actin cytoskeleton in pollen tubes; actin and actin binding proteins

Abstract

Actin cytoskeleton is well known to be a key element for the germination and the elongation of pollen tubes. It has been appreciated that the cytoplasmic streaming for conveying secretory vesicles to the tube apex is a primary function of the actin cytoskeleton in pollen tubes. Recently growing evidence has revealed that highly dynamic populations of actin cytoskeleton are present in apical and subapical regions of tubes and are involved intimately in polar elongation of tubes. Tip-focused Ca2+-gradient and tip-localized small GTPases (Rop/Rac) are believed to control such actin dynamics through the various kinds of actin binding proteins (ABPs). In the present chapter, we focus on the organization of actin in elongating pollen tubes and characterization of ABPs identified from pollen. We further discuss their roles, with special emphasis on recently identified proteins of the gelsolin family, regulating actin dynamics and organizing actin architecture in pollen tubes. © Springer-Verlag Berlin Heidelberg 2006.