Structural analysis of microtubule binding by minus-end targeting protein Spiral2.

Microtubules (MTs) are dynamic cytoskeletal polymers that play a critical role in determining cell polarity and shape. In plant cells, acentrosomal MTs are localized on the cell surface and are referred to as cortical MTs. Cortical MTs nucleate in the cell cortex and detach from nucleation sites.

Confined-microtubule assembly shapes three-dimensional cell wall structures in xylem vessels.

Properly patterned deposition of cell wall polymers is prerequisite for the morphogenesis of plant cells. A cortical microtubule array guides the two-dimensional pattern of cell wall deposition. Yet, the mechanism underlying the three-dimensional patterning of cell wall deposition is poorly understood.

A Quantitative Method for Evaluating Phragmoplast Morphology.

Phragmoplasts are plant-specific microtubule structures that form cell plates at the cell division plane. During late anaphase, phragmoplasts emerge between daughter nuclei as the derivative of spindle microtubules, and centrifugally expand toward the cell cortex to build cell plates during telophase. Phragmoplasts are composed of short antiparallel microtubules decorated with various microtubule-associated proteins.

A Novel Katanin-Tethering Machinery Accelerates Cytokinesis.

Cytokinesis is fundamental for cell proliferation [1, 2]. In plants, a bipolar short-microtubule array forms the phragmoplast, which mediates vesicle transport to the midzone and guides the formation of cell walls that separate the mother cell into two daughter cells [2]. The phragmoplast centrifugally expands toward the cell cortex to guide cell-plate formation at the cortical division site [3, 4].

Imaging of Developing Metaxylem Vessel Elements in Cultured Hypocotyls.

An in vitro induction system for xylem vessel formation is a useful tool for visualizing the differentiation of xylem vessel cells. A procedure for inducing xylem vessel cell differentiation in hypocotyls of Arabidopsis thaliana is described here. Metaxylem vessel elements form ectopically in excised hypocotyl tissue following treatment with bikinin.

A Rho-based reaction-diffusion system governs cell wall patterning in metaxylem vessels.

Rho GTPases play crucial roles in cell polarity and pattern formation. ROPs, Rho of plant GTPases, are widely involved in cell wall patterning in plants, yet the molecular mechanism underlying their action remains unknown. Arabidopsis ROP11 is locally activated to form plasma membrane domains, which direct formation of cell wall pits in metaxylem vessel cells through interaction with cortical microtubules.

CORTICAL MICROTUBULE DISORDERING1 Is Required for Secondary Cell Wall Patterning in Xylem Vessels.

Proper patterning of the cell wall is essential for plant cell development. Cortical microtubule arrays direct the deposition patterns of cell walls at the plasma membrane. However, the precise mechanism underlying cortical microtubule organization is not well understood.

Shoot-derived cytokinins systemically regulate root nodulation.

Legumes establish symbiotic associations with nitrogen-fixing bacteria (rhizobia) in root nodules to obtain nitrogen. Legumes control nodule number through long-distance communication between roots and shoots, maintaining the proper symbiotic balance. Rhizobial infection triggers the production of mobile CLE-RS1/2 peptides in Lotus japonicus roots; the perception of the signal by receptor kinase HAR1 in shoots presumably induces the production of an unidentified shoot-derived inhibitor (SDI) that translocates to roots and blocks further nodule development.