Phytohormone cytokinin guides microtubule dynamics during cell progression from proliferative to differentiated stage

Abstract

Cell production and differentiation for the acquisition of specific functions are key features of living systems. The dynamic network of cellular microtubules provides the necessary platform to accommodate processes associated with the transition of cells through the individual phases of cytogenesis. Here, we show that the plant hormone cytokinin fine‐tunes the activity of the microtubular cytoskeleton during cell differentiation and counteracts microtubular rearrangements driven by the hormone auxin. The endogenous upward gradient of cytokinin activity along the longitudinal growth axis in Arabidopsis thaliana roots correlates with robust rearrangements of the microtubule cytoskeleton in epidermal cells progressing from the proliferative to the differentiation stage. Controlled increases in cytokinin activity result in premature re‐organization of the microtubule network from transversal to an oblique disposition in cells prior to their differentiation, whereas attenuated hormone perception delays cytoskeleton conversion into a configuration typical for differentiated cells. Intriguingly, cytokinin can interfere with microtubules also in animal cells, such as leukocytes, suggesting that a cytokinin‐sensitive control pathway for the microtubular cytoskeleton may be at least partially conserved between plant and animal cells.

General Patterns and Species-Specific Differences in the Organization of the Tubulin Cytoskeleton in Indeterminate Nodules of Three Legumes

“…[ 45 , 46 ]. Recently, it was demonstrated that cytokinins control the rearrangement of cortical microtubules from transverse orientation in the transition and elongation zones to oblique orientation in the differentiation zone in the epidermal cells of A. thaliana root [ 47 ]. Intriguingly, the localization of auxin in the symbiotic nodules of L. japonicus [ 48 ] and P. sativum [ 49 ] is limited to the meristem and vascular tissues.…”

Integrative Roles of Phytohormones on Cell Proliferation, Elongation and Differentiation in the Arabidopsis thaliana Primary Root

“…Interestingly, the root cell elongation is also inhibited using a high IAA concentration (250nm) or in the OE of YUC6 compared to control conditions, probably by a transitory alkalinization of the apoplast ( Barbez et al, 2017 ; Figure 4B ). Moreover, cells in the EZ have transversal microtubules that are more sensitive to auxin−driven reorientation of the microtubule network to longitudinal disposition than in other PR zones leading to a reduced cellular elongation rate ( Montesinos et al, 2020 ). Additionally, many different PIN mutants have a reduction in the cell elongation size compared to WT and high levels of PLT2 expression or PLT2 protein in the EZ inhibit cell elongation ( Galinha et al, 2007 ; Mähönen et al, 2014 ) ( Blilou et al, 2005 ).…”

GR24, A Synthetic Strigolactone Analog, and Light Affect the Organization of Cortical Microtubules in Arabidopsis Hypocotyl Cells

“…For example, ethylene has inhibitory effects in dark conditions, and its action is canceled after the hypocotyl emerges from the soil and becomes exposed to ambient light ( Yu and Huang, 2017 ). Meanwhile, auxin promotes hypocotyl elongation in light conditions, but has rudimentary effects in the dark ( Jensen et al, 1998 ), while cytokinins establish an acropetal root gradient underlying the developmental zonation of the root ( Montesinos et al, 2020 ).…”