Abstract
Cytokinesis is accomplished in higher plants by the phragmoplast, creating and conducting the cell plate to separate daughter nuclei by a new cell wall. The microtubule-severing enzyme p60-katanin plays an important role in the centrifugal expansion and timely disappearance of phragmoplast microtubules. Consequently, aberrant structure and delayed expansion rate of the phragmoplast have been reported to occur in p60-katanin mutants. Here, the consequences of p60-katanin malfunction in cell plate/daughter wall formation were investigated by transmission electron microscopy (TEM), in root cells of the fra2 Arabidopsis thaliana loss-of-function mutant. In addition, deviations in the chemical composition of cell plate/new cell wall were identified by immunolabeling and confocal microscopy. It was found that, apart from defective phragmoplast microtubule organization, cell plates/new cell walls also appeared faulty in structure, being unevenly thick and perforated by large gaps. In addition, demethylesterified homogalacturonans were prematurely present in fra2 cell plates, while callose content was significantly lower than in the wild type. Furthermore, KNOLLE syntaxin disappeared from newly formed cell walls in fra2 earlier than in the wild type. Taken together, these observations indicate that delayed cytokinesis, due to faulty phragmoplast organization and expansion, results in a loss of synchronization between cell plate growth and its chemical maturation.
Highlights
Cytokinesis, the process by which parent cells divide after karyokinesis, is accomplished in higher plants by the function of the phragmoplast [1,2,3]
Cell plate is built by dictyosome-derived vesicles, the fusion of which into a unified cell plate is mediated by KNOLLE, a cytokinesis-specific plant syntaxin that, apart from being recruited to the cell plate, persists for a while on newly built cell walls [6,7]
Cell plate consists mainly of callose, offering integrity and rigidity, and highly methylesterified pectins, while a milestone of its maturation is the replacement of callose by cellulose and the de-esterification of pectins [8]
Summary
Cytokinesis, the process by which parent cells divide after karyokinesis, is accomplished in higher plants by the function of the phragmoplast [1,2,3]. An array of two anti-parallel microtubule groups, originally deriving by the central spindle, mediates the formation of a cell plate, consisting of fusing dictyosome vesicles [3,4]. These microtubules are perpendicular to the cell plate, with their plus ends pointing toward the equatorial region [5]. Both the phragmoplast and cell plate initiate between the separated chromosome groups at telophase, expand centrifugally to meet the parent cell wall at the cortical division site [3,4,5]. After expansion outside the daughter nuclei zone and initial cell plate stabilization, phragmoplast microtubules are typically short, perpendicular to the cell plate, eventually disappearing after the final fusion of the cell plate with parent cell walls [9]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
