Katanin: A Sword Cutting Microtubules for Cellular, Developmental, and Physiological Purposes

Abstract

KATANIN is a well-studied microtubule severing protein affecting microtubule organization and dynamic properties in higher plants. By regulating mitotic and cytokinetic and cortical microtubule arrays it is involved in the progression of cell division and cell division plane orientation. KATANIN is also involved in cell elongation and morphogenesis during plant growth. In this way KATANIN plays critical roles in diverse plant developmental processes including the development of pollen, embryo, seed, meristem, root, hypocotyl, cotyledon, leaf, shoot, and silique. KATANIN-dependent microtubule regulation seems to be under the control of plant hormones. This minireview provides an overview on available KATANIN mutants and discusses advances in our understanding of KATANIN biological roles in plants.

Keywords: cell division; cell growth; cytoskeleton; hormone; katanin; microtubules; morphogenesis; plant development.

Figure 1

Morphological phenotypes of KATANIN mutants vs. Col-0 wild-type (7 days old seedlings). (A) Representative pictures of whole Col-0 seedlings and KATANIN mutants. Note much shorter roots in the mutants. (B) Detailed pictures of above ground seedling parts in Col-0 and KATANIN mutants. (C) Detailed pictures of primary root tips of Col-0 and KATANIN mutants. Note radial expansion of mutant roots. Scale bars = 5 mm (A); 1 mm (B); 250 μm (C).

Figure 2

Differences in the microtubule organization and cell shape of Arabidopsis thaliana Col-0 and ktn1-2 petiole epidermal cells carrying a GFP-TUA6 microtubule marker after spinning disk microscopy imaging. In differentiated cells, most cortical microtubules are transversal to the cell axis in Col-0 showing parallel placement to each other (A) resulting in relatively narrow angular distribution (C) whereas they appear more disorganized and randomly oriented in ktn1-2 (B) exhibiting broader angular distribution pattern (D). Scale bar = 10 μm.