Actin cytoskeleton in plants: from transport networks to signaling networks.
The plant actin cytoskeleton is characterized by a high diversity in regard to gene families, isoforms, and degree of polymerization. In addition to the most abundant F-actin assemblies like filaments and their bundles, G-actin obviously assembles in the form of actin oligomers composed of a few actin molecules which can be extensively cross-linked into complex dynamic meshworks. The role of the actomyosin complex as a force generating system - based on principles operating as in muscle cells - is clearly established for long-range mass transport in large algal cells and specialized cell types of higher plants. Extended F-actin networks, mainly composed of F-actin bundles, are the structural basis for this cytoplasmic streaming of high velocities On the other hand, evidence is accumulating that delicate meshworks built of short F-actin oligomers are critical for events occurring at the plasma membrane, e.g., actin interventions into activities of ion channels and hormone carriers, signaling pathways based on phospholipids, and exo- and endocytotic processes. These unique F-actin arrays, constructed by polymerization-depolymerization processes propelled via synergistic actions of actin-binding proteins such as profilin and actin depolymerizing factor (ADF)/cofilin are supposed to be engaged in diverse aspects of plant morphogenesis. Finally, rapid rearrangements of F-actin meshworks interconnecting endocellular membranes turn out to be especially important for perception-signaling purposes of plant cells, e.g., in association with guard cell movements, mechano- and gravity-sensing, plant host-pathogen interactions, and wound-healing.
Volkmann
D
D
Botany Institute, University of Bonn, Germany. unb110@uni-bonn.de
Baluska
F
F
D000199:Actins / Q000032:analysis / Q000502:physiology*; D016764:Cell Polarity; D048429:Cell Size; D002736:Chloroplasts / Q000378:metabolism; D003599:Cytoskeleton / Q000737:chemistry*; D056890:Eukaryota / Q000166:cytology; D007150:Immunohistochemistry; D007365:Intercellular Junctions / Q000737:chemistry; D008854:Microscopy, Electron; D009218:Myosins / Q000502:physiology; D010944:Plants / Q000648:ultrastructure*; D018087:Plastids / Q000502:physiology; D015398:Signal Transduction; D014945:Wound Healing / Q000502:physiology
D000199:Actins; D009218:Myosins