Effect of osmotic pressure on root growth, cell cycle and cell elongation

Abstract In the fission yeast Schizosaccharomyces pombe, as in other eukaryotic cells, Cdc2/cyclin B complex is the key regulator of mitosis. Perhaps the most important regulation of Cdc2 is the inhibitory phosphorylation of tyrosine-15 that is catalyzed by Wee1 and Mik1. Cdc25 and Pyp3 phosphatases dephosphorylate tyrosine-15 and activate Cdc2. To isolate novel activators of Cdc2 kinase, we screened synthetic lethal mutants in a cdc25-22 background at the permissive temperature (25°). One of the genes, slm9, encodes a novel protein of 807 amino acids. Slm9 is most similar to Hir2, the histone gene regulator in budding yeast. Slm9 protein level is constant and Slm9 is localized to the nucleus throughout the cell cycle. The slm9 disruptant is delayed at the G2-M transition as indicated by cell elongation and analysis of DNA content. Inactivation of Wee1 fully suppressed the cell elongation phenotype caused by the slm9 mutation. The slm9 mutant is defective in recovery from G1 arrest after nitrogen starvation. The slm9 mutant is also UV sensitive, showing a defect in recovery from the cell cycle arrest after UV irradiation.

Download Full-text

Developmentally distinct activities of the exocyst enable rapid cell elongation and determine meristem size during primary root growth in Arabidopsis

BMC Plant Biology ◽

10.1186/s12870-014-0386-0 ◽

2014 ◽

Vol 14 (1) ◽

Cited By ~ 12

Author(s):

Rex A Cole ◽

Samantha A McInally ◽

John E Fowler

Keyword(s):

Root Growth ◽

Cell Elongation ◽

Primary Root ◽

Meristem Size ◽

Primary Root Growth

Download Full-text

Lateral Root Priming Synergystically Arises from Root Growth and Auxin Transport Dynamics

10.1101/361709 ◽

2018 ◽

Cited By ~ 2

Author(s):

Thea van den Berg ◽

Kirsten H. ten Tusscher

Keyword(s):

Cell Cycle ◽

Root Growth ◽

Lateral Root ◽

Root Formation ◽

Growth Dynamics ◽

Root Tip ◽

Cycle Duration ◽

Elongation Zone ◽

Lateral Root Formation ◽

Cell Cycle Duration

AbstractThe root system is a major determinant of plant fitness. Its capacity to supply the plant with sufficient water and nutrients strongly depends on root system architecture, which arises from the repeated branching off of lateral roots. A critical first step in lateral root formation is priming, which prepatterns sites competent of forming a lateral root. Priming is characterized by temporal oscillations in auxin, auxin signalling and gene expression in the root meristem, which through growth become transformed into a spatially repetitive pattern of competent sites. Previous studies have demonstrated the importance of auxin synthesis, transport and perception for the amplitude of these oscillations and their chances of producing an actual competent site. Additionally, repeated lateral root cap apoptosis was demonstrated to be strongly correlated with repetitive lateral root priming. Intriguingly, no single mutation has been identified that fully abolishes lateral root formation, and thusfar the mechanism underlying oscillations has remained unknown. In this study, we investigated the impact of auxin reflux loop properties combined with root growth dynamics on priming, using a computational approach. To this end we developed a novel multi-scale root model incorporating a realistic root tip architecture and reflux loop properties as well as root growth dynamics. Excitingly, in this model, repetitive auxin elevations automatically emerge. First, we show that root tip architecture and reflux loop properties result in an auxin loading zone at the start of the elongation zone, with preferential auxin loading in narrow vasculature cells. Second, we demonstrate how meristematic root growth dynamics causes regular alternations in the sizes of cells arriving at the elongation zone, which subsequently become amplified during cell expansion. These cell size differences translate into differences in cellular auxin loading potential. Combined, these properties result in temporal and spatial fluctuations in auxin levels in vasculature and pericycle cells. Our model predicts that temporal priming frequency predominantly depends on cell cycle duration, while cell cycle duration together with meristem size control lateral root spacing.

Download Full-text

Bundling up the Role of the Actin Cytoskeleton in Primary Root Growth

Frontiers in Plant Science ◽

10.3389/fpls.2021.777119 ◽

2021 ◽

Vol 12 ◽

Author(s):

Judith García-González ◽

Kasper van Gelderen

Keyword(s):

Root Growth ◽

Actin Cytoskeleton ◽

Cell Elongation ◽

Feedback Loop ◽

Primary Root ◽

Actin Binding ◽

Actin Network ◽

Actin Organization ◽

Primary Root Growth

Primary root growth is required by the plant to anchor in the soil and reach out for nutrients and water, while dealing with obstacles. Efficient root elongation and bending depends upon the coordinated action of environmental sensing, signal transduction, and growth responses. The actin cytoskeleton is a highly plastic network that constitutes a point of integration for environmental stimuli and hormonal pathways. In this review, we present a detailed compilation highlighting the importance of the actin cytoskeleton during primary root growth and we describe how actin-binding proteins, plant hormones, and actin-disrupting drugs affect root growth and root actin. We also discuss the feedback loop between actin and root responses to light and gravity. Actin affects cell division and elongation through the control of its own organization. We remark upon the importance of longitudinally oriented actin bundles as a hallmark of cell elongation as well as the role of the actin cytoskeleton in protein trafficking and vacuolar reshaping during this process. The actin network is shaped by a plethora of actin-binding proteins; however, there is still a large gap in connecting the molecular function of these proteins with their developmental effects. Here, we summarize their function and known effects on primary root growth with a focus on their high level of specialization. Light and gravity are key factors that help us understand root growth directionality. The response of the root to gravity relies on hormonal, particularly auxin, homeostasis, and the actin cytoskeleton. Actin is necessary for the perception of the gravity stimulus via the repositioning of sedimenting statoliths, but it is also involved in mediating the growth response via the trafficking of auxin transporters and cell elongation. Furthermore, auxin and auxin analogs can affect the composition of the actin network, indicating a potential feedback loop. Light, in its turn, affects actin organization and hence, root growth, although its precise role remains largely unknown. Recently, fundamental studies with the latest techniques have given us more in-depth knowledge of the role and organization of actin in the coordination of root growth; however, there remains a lot to discover, especially in how actin organization helps cell shaping, and therefore root growth.

Download Full-text

Changes in the osmotic pressure of E. coli W7 during the cell cycle

Ultramicroscopy ◽

10.1016/0304-3991(79)90034-2 ◽

1979 ◽

Vol 4 (1) ◽

pp. 121

Author(s):

C.G. van Eden ◽

R.W.H. Verwer ◽

N. Nanninga

Keyword(s):

Cell Cycle ◽

Osmotic Pressure ◽

E Coli

Download Full-text

Defective root growth triggered by oxidative stress is controlled through the expression of cell cycle-related genes

Plant Science ◽

10.1016/j.plantsci.2012.08.011 ◽

2012 ◽

Vol 197 ◽

pp. 30-39 ◽

Cited By ~ 26

Author(s):

Hironaka Tsukagoshi

Keyword(s):

Oxidative Stress ◽

Cell Cycle ◽

Root Growth

Download Full-text

Publisher Correction: Osmotic pressure modulates single cell cycle dynamics inducing reversible growth arrest and reactivation of human metastatic cells

Scientific Reports ◽

10.1038/s41598-021-99039-9 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Hubert M. Taïeb ◽

Daniela S. Garske ◽

Jörg Contzen ◽

Manfred Gossen ◽

Luca Bertinetti ◽

...

Keyword(s):

Cell Cycle ◽

Single Cell ◽

Osmotic Pressure ◽

Growth Arrest ◽

Metastatic Cells ◽

Cell Cycle Dynamics

Download Full-text

Nitrogen Deficiency-Induced Decrease in Cytokinins Content Promotes Rice Seminal Root Growth by Promoting Root Meristem Cell Proliferation and Cell Elongation

Cells ◽

10.3390/cells9040916 ◽

2020 ◽

Vol 9 (4) ◽

pp. 916

Author(s):

Qi Wang ◽

Yanchun Zhu ◽

Xiao Zou ◽

Fengfeng Li ◽

Jialiang Zhang ◽

...

Keyword(s):

Cell Proliferation ◽

Root Growth ◽

Cell Elongation ◽

Developmental Plasticity ◽

Root Meristem ◽

Seminal Root ◽

Down Regulation ◽

Meristem Cell ◽

Root Meristem Cell ◽

N Deficiency

Rice (Oryza sativa L.) seedlings grown under nitrogen (N) deficiency conditions show a foraging response characterized by increased root length. However, the mechanism underlying this developmental plasticity is still poorly understood. In this study, the mechanism by which N deficiency influences rice seminal root growth was investigated. The results demonstrated that compared with the control (1 mM N) treatment, N deficiency treatments strongly promoted seminal root growth. However, the N deficiency-induced growth was negated by the application of zeatin, which is a type of cytokinin (CK). Moreover, the promotion of rice seminal root growth was correlated with a decrease in CK content, which was due to the N deficiency-mediated inhibition of CK biosynthesis through the down-regulation of CK biosynthesis genes and an enhancement of CK degradation through the up-regulation of CK degradation genes. In addition, the N deficiency-induced decrease in CK content not only enhanced the root meristem cell proliferation rate by increasing the meristem cell number via the down-regulation of OsIAA3 and up-regulation of root-expressed OsPLTs, but also promoted root cell elongation by up-regulating cell elongation-related genes, including root-specific OsXTHs and OsEXPs. Taken together, our data suggest that an N deficiency-induced decrease in CK content promotes the seminal root growth of rice seedlings by promoting root meristem cell proliferation and cell elongation.

Download Full-text