3D analysis of mitosis distribution highlights the longitudinal zonation and diarch symmetry in proliferation activity of the Arabidopsis thaliana root meristem

Abstract

To date CYCB1;1 marker and cortex cell lengths have been conventionally used to determine the proliferation activity of the Arabidopsis root meristem. By creating a 3D map of mitosis distribution we showed that these markers overlooked that stele and endodermis save their potency to divide longer than the cortex and epidermis. Cessation of cell divisions is not a random process, so that mitotic activity within the endodermis and stele shows a diarch pattern. Mitotic activity of all root tissues peaked at the same distance from the quiescent center (QC); however, different tissues stopped dividing at different distances, with cells of the protophloem exiting the cell cycle first and the procambial cells being the last. The robust profile of mitotic activity in the root tip defines the longitudinal zonation in the meristem with the proliferation domain, where all cells are able to divide; and the transition domain, where the cell files cease to divide. 3D analysis of cytokinin deficient and cytokinin signaling mutants showed that their proliferation domain is similar to that of the wild type, but the transition domain is much longer. Our data suggest a strong inhibitory effect of cytokinin on anticlinal cell divisions in the stele.

Global analysis of an exponential model of cell proliferation for estimation of cell cycle duration in the root apical meristem of angiosperms

“…However, these conclusions were drawn based on labelled mitosis curves and did not consider the exponential age distribution of cells within the RAM (Ivanov, 1974(Ivanov, , 1994Webster and Davidson, 1980). Our analysis showed that the proximal portion of the RAM represents a transition domain where cells still divide (Lavrekha et al, 2017), and the relative cell growth rate is the same as in the rest of the RAM (Ivanov and Dubrovsky, 2013). Also, the duration of the last cell cycle in the RAM is the same as in the proliferation domain (Balodis and Ivanov, 1970), but exit from the cell cycle at the end of the RAM is a heterogeneous process.…”

At-Hook Motif Nuclear Localised Protein 18 as a Novel Modulator of Root System Architecture

“…The formation of new LRs is a multistep process confined to the competent sector of the pericycle [54][55][56]. These cells exhibit a specific and prolonged cell cycling pattern [55,57,58] retaining their meristematic character (cell size, vacuolization, large nuclei and dense cytoplasm, G2 phase, cell division) longer than other root tissues [55,59,60]. ABERRANT LATERAL ROOT FORMATION 4 (ALF4) [61] is modulator of lateral root initiation maintaining the pericycle in a mitotically competent state [62].…”

Alfalfa Root Growth Rate Correlates with Progression of Microtubules during Mitosis and Cytokinesis as Revealed by Environmental Light-Sheet Microscopy

“…Complex analyses of cell division and elongation patterns during primary root growth and development were mostly performed in model plants such as Arabidopsis (e.g., Beemster and Baskin, 1998 ; Beemster et al, 2002 ; Lavrekha et al, 2017 ), maize (e.g., Sacks et al, 1997 ), barley (e.g., Kirschner et al, 2017 ), tobacco (e.g., Pasternak et al, 2017 ) and rice (e.g., Rebouillat et al, 2009 ; Ni et al, 2014 ). These studies were mostly based on 3D reconstruction analyses from fixed plant samples.…”