The relation between cell size, chromosome length and the orientation of chromosomes in dividing root cortex cells

Salinity is one of the most serious agricultural problems that adversely affects growth and productivity of pasture crops such as alfalfa. In this study, the effects of salinity on some ecophysiological and biochemical criteria associated with salt tolerance were assessed in two Moroccan alfalfa (Medicago sativa L.) populations, Taf 1 and Tata. The experiment was conducted in a hydro-aeroponic system containing nutrient solutions, with the addition of NaCl at concentrations of 100 and 200 mM. The salt stress was applied for a month. Several traits in relation to salt tolerance, such as plant dry biomass, relative water content, leaf gas exchange, chlorophyll fluorescence, nutrient uptake, lipid peroxidation and antioxidant enzymes, were analyzed at the end of the experiment. The membrane potential was measured in root cortex cells of plants grown with or without NaCl treatment during a week. The results indicated that under salt stress, plant growth and all of the studied physiological and biochemical traits were significantly decreased, except for malondialdehyde and H2O2 contents, which were found to be increased under salt stress. Depolarization of membrane root cortex cells with the increase in external NaCl concentration was noted, irrespective of the growth conditions. The Tata population was more tolerant to high salinity (200 mM NaCl) and its tolerance was associated with the ability of plants to maintain adequate levels of the studied parameters and their ability to overcome oxidative stress by the induction of antioxidant enzymes, such as guaiacol peroxidase, catalase and superoxide dismutase.

Download Full-text

Einfluß von Tetraphenylborat auf die Feinstruktur von Zellen der Maiswurzelspitze / Influence of Tetraphenylboron on Fine Structure of Cells of Corn Root Tips

Zeitschrift für Naturforschung B ◽

10.1515/znb-1970-1234 ◽

1970 ◽

Vol 25 (12) ◽

pp. 1477-1479 ◽

Cited By ~ 7

Author(s):

Charlotte Hecht-Buchholz ◽

Horst Marschner

Keyword(s):

Fine Structure ◽

Membrane Structure ◽

Endoplasmatic Reticulum ◽

Root Tips ◽

Root Cortex ◽

Double Membrane ◽

Corn Root ◽

Ca 50 ◽

Root Cortex Cells

Treatment (1-3h) of corn root tips with 5 × 10-5ᴍ tetraphenylboron (TPB) caused characteristic changes of the membrane structure in the outer layers of the root cortex cells. The mitochondria had lost their inner structure. At the double membrane of the mitochondria and at the membrane plasmalemma, tonoplast, and endoplasmatic reticulum there appeared numerous osmiophilic globuli (ca. 50 nm). The permeability of the membranes seemed to be increased extremely. It is suggested that the lipoproteine complex of the membranes was destroyed by interaction of TPB with ammonium groups of the membrane constituents

Download Full-text

Identification and characterization of inward K+ -channels in plasma membranes ofArabidopsis root cortex cells

Science in China Series C Life Sciences ◽

10.1007/bf03183608 ◽

1999 ◽

Vol 42 (3) ◽

pp. 307-315 ◽

Cited By ~ 1

Author(s):

Chuanjiang Yu ◽

Weihua Wu

Keyword(s):

Plasma Membranes ◽

Root Cortex ◽

K Channels ◽

Root Cortex Cells ◽

Identification And Characterization

Download Full-text

Mitotic chromosome length scales in response to both cell and nuclear size

The Journal of Cell Biology ◽

10.1083/jcb.201502092 ◽

2015 ◽

Vol 209 (5) ◽

pp. 645-652 ◽

Cited By ~ 28

Author(s):

Anne-Marie Ladouceur ◽

Jonas F. Dorn ◽

Paul S. Maddox

Keyword(s):

Cell Size ◽

Chromosome Segregation ◽

Mitotic Spindle ◽

Mitotic Chromosome ◽

Time Lapse ◽

Chromosome Length ◽

Nuclear Size ◽

Multicellular Development ◽

Length Regulation ◽

Cellular Integrity

Multicellular development requires that cells reduce in size as a result of consecutive cell divisions without increase in embryo volume. To maintain cellular integrity, organelle size adapts to cell size throughout development. During mitosis, the longest chromosome arm must be shorter than half of the mitotic spindle for proper chromosome segregation. Using high-resolution time-lapse microscopy of living Caenorhabditis elegans embryos, we have quantified the relation between cell size and chromosome length. In control embryos, chromosome length scaled to cell size. Artificial reduction of cell size resulted in a shortening of chromosome length, following a trend predicted by measurements from control embryos. Disturbing the RAN (Ras-related nuclear protein)-GTP gradient decoupled nuclear size from cell size and resulted in chromosome scaling to nuclear size rather than cell size; smaller nuclei contained shorter chromosomes independent of cell size. In sum, quantitative analysis relating cell, nuclear, and chromosome size predicts two levels of chromosome length regulation: one through cell size and a second in response to nuclear size.

Download Full-text

Spatial differences in stoichiometry of EGR phosphatase and Microtubule-Associated Stress Protein 1 control root meristem activity during drought stress.

10.1101/2021.10.06.463370 ◽

2021 ◽

Author(s):

Toshisagba Longkumer ◽

Chih-Yun Chen ◽

Marco Biancucci ◽

Bhaskara Govinal Badiger ◽

Paul E. Verslues

Keyword(s):

Cell Division ◽

Cell Size ◽

Cell Expansion ◽

Growth Regulation ◽

Root Meristem ◽

Stress Protein ◽

Root Cell ◽

Root Cortex ◽

Meristem Cell ◽

Meristem Size

During moderate severity drought and low water potential (Ψw) stress, poorly understood signaling mechanisms restrict both meristem cell division and subsequent cell expansion. We found that the Clade E Growth-Regulating 2 (EGR2) protein phosphatase and Microtubule Associated Stress Protein 1 (MASP1) differed in their stoichiometry of expression across the root meristem and had opposing effects on root meristem activity at low Ψw. Ectopic MASP1 or EGR expression increased or decreased, respectively, root meristem size and root elongation during low Ψw stress. This, along with the ability of phosphomimic MASP1 to overcome EGR suppression of root meristem size and observation that ectopic EGR expression had no effect on unstressed plants, indicated that during low Ψw EGR activation and attenuation of MASP1 phosphorylation in their overlapping zone of expression determines root meristem size and activity. Ectopic EGR expression also decreased root cell size at low Ψw. Conversely, both the egr1-1egr2-1 and egr1-1egr2-1masp1-1 mutants had similarly increased root cell size; but, only egr1-1egr2-1 had increased cell division. These observations demonstrated that EGRs affect meristem activity via MASP1 but affect cell expansion via other mechanisms. Interestingly, EGR2 was highly expressed in the root cortex, a cell type important for growth regulation and environmental response.

Download Full-text

Mechanism of kinetin-induced death of Vicia faba ssp. minor root cortex cells

Scientific Reports ◽

10.1038/s41598-021-03103-3 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Andrzej Kaźmierczak ◽

Anita Kunikowska ◽

Magdalena Doniak ◽

Andrzej Kornaś

Keyword(s):

Cell Death ◽

Vicia Faba ◽

Permeability Transition ◽

Ruthenium Red ◽

Root Cortex ◽

Raf Kinase ◽

Cytokinin Receptors ◽

Root Cortex Cells ◽

Exogenous Factors

AbstractCell death (CD) may be induced by endogenous or exogenous factors and contributes to all the steps of plant development. This paper presents results related to the mechanism of CD regulation induced by kinetin (Kin) in the root cortex of Vicia faba ssp. minor. To explain the process, 6-(2-hydroxy-3-methylbenzylamino)purine (PI-55), adenine (Ad), 5′-amine-5′-deoxyadenosine (Ado) and N-(2-chloro-4-piridylo)-N′-phenylurea (CPPU) were applied to (i) block cytokinin receptors (CKs) and inhibit the activities of enzymes of CK metabolism, i.e., (ii) phosphoribosyltransferase, (iii) kinases, and (iv) oxidases, respectively. Moreover, ethylene glycol-bis(β-aminoethyl ether)-N,N,N′,N′-tetraacetic acid (EGTA), lanthanum chloride (LaCl3), ruthenium red (RRed) and cyclosporine A (CS-A) were applied to (i) chelate extracellular calcium ions (Ca2+) as well as blocks of (ii) plasma-, (iii) endoplasmic reticulum- (ER) membrane Ca2+ ion channels and (iv) mitochondria- (MIT) Ca2+ ions release by permeability transition por (PTP), respectively. The measured physiological effectiveness of these factors was the number of living and dying cortex cells estimated with orange acridine (OA) and ethidium bromide (EB), the amounts of cytosolic Ca2+ ions with chlortetracycline (CTC) staining and the intensity of chromatin and Ca2+-CTC complex fluorescence, respectively. Moreover, the role of sorafenib, an inhibitor of RAF kinase, on the vitality of cortex cells and ethylene levels as well as the activities of RAF-like kinase and MEK2 with Syntide-2 and Mek2 as substrates were studied. The results clarified the previously presented suggestion that Kin is converted to appropriate ribotides (5′-monophosphate ribonucleotides), which cooperate with the ethylene and Ca2+ ion signalling pathways to transduce the signal of kinetin-programmed cell death (Kin-PCD). Based on the present and previously published results related to Kin-PCD, the crosstalk between ethylene and MAP kinase signalling, as well as inhibitors of CK receptors and enzymes of their metabolism, is proposed.

Download Full-text