scholarly journals Root-specific reduction of cytokinin perception enhances shoot growth with an alteration of trans-zeatin distribution in Arabidopsis thaliana

2021 ◽  
Author(s):  
Kota Monden ◽  
Mikiko Kojima ◽  
Yumiko Takebayashi ◽  
Takamasa Suzuki ◽  
Tsuyoshi Nakagawa ◽  
...  
Keyword(s):  
Shoot Growth ◽  
The Body ◽  
Marker Genes ◽  
Double Knockout ◽  
Long Distance ◽  
Long Distance Transport ◽  
Solid Media ◽  
Novel Approach ◽  
Isopentenyl Adenine ◽  
Knockout Line

AbstractCompelling evidence demonstrates that root-derived cytokinins (CKs) contribute to shoot growth via long-distance transport; therefore, we hypothesized that an increase in root-derived CKs enhances shoot growth. To demonstrate this, we grafted Arabidopsis Col-0 (WT) scion onto rootstock originated from WT or a double-knockout line of CK receptors AHK2 and AHK3 (ahk23) because the knockout line over accumulates CKs in the body due to feedback homeostasis regulation. The grafted plants (scion/rootstock: WT/WT and WT/ahk23) were grown in vermiculite pots or solid media under high and low nitrogen regimes for vegetative growth and biochemical analysis. The root-specific deficiency of AHK2 and AHK3 increased root concentrations of trans-zeatin (tZ)-type and N6-(Δ2-isopentenyl) adenine (iP)-type CKs, induced CK biosynthesis genes, and repressed CK degradation genes in the root. Shoot growth, shoot concentrations of tZ-type CKs, and shoot expression of CK-inducible marker genes were consistently larger in the WT/ahk23 plants than in the WT/WT plants. Moreover, the root-specific deficiency of AHK2 and AHK3 enhanced shoot growth in the WT scion more strongly than in the ahk23 scion. Given that tZ-type CKs are predominantly produced from iP-type CKs in the root and xylem-mobile, it is concluded that the root-specific reduction of CK perception would enhance shoot growth by increasing the amount of root-derived tZ-type CKs and their perception by the shoot. This study will present a novel approach to improve plant growth and productivity.

Phloem long-distance transport of CmNACP mRNA: implications for supracellular regulation in plants

Development ◽  
1999 ◽  
Vol 126 (20) ◽  
pp. 4405-4419 ◽  
Author(s):  
R. Ruiz-Medrano ◽  
B. Xoconostle-Cazares ◽  
W.J. Lucas
Keyword(s):  
Higher Plants ◽  
Phloem Transport ◽  
The Body ◽  
Pcr Analysis ◽  
Rt Pcr ◽  
Long Distance ◽  
Rna Molecules ◽  
Long Distance Transport ◽  
Meristem Development

Direct support for the concept that RNA molecules circulate throughout the plant, via the phloem, is provided through the characterisation of mRNA from phloem sap of mature pumpkin (Cucurbita maxima) leaves and stems. One of these mRNAs, CmNACP, is a member of the NAC domain gene family, some of whose members have been shown to be involved in apical meristem development. In situ RT-PCR analysis revealed the presence of CmNACP RNA in the companion cell-sieve element complex of leaf, stem and root phloem. Longitudinal and transverse sections showed continuity of transcript distribution between meristems and sieve elements of the protophloem, suggesting CmNACP mRNA transport over long distances and accumulation in vegetative, root and floral meristems. In situ hybridization studies conducted on CmNACP confirmed the results obtained using in situ RT-PCR. Phloem transport of CmNACP mRNA was proved directly by heterograft studies between pumpkin and cucumber plants, in which CmNACP transcripts were shown to accumulate in cucumber scion phloem and apical tissues. Similar experiments were conducted with 7 additional phloem-related transcripts. Collectively, these studies established the existence of a system for the delivery of specific mRNA transcripts from the body of the plant to the shoot apex. These findings provide insight into the presence of a novel mechanism likely used by higher plants to integrate developmental and physiological processes on a whole-plant basis.

Mercury

1989 ◽  
Vol 8 (7) ◽  
pp. 1291-1295 ◽  
Author(s):  
Thomes W. Clarkson
Keyword(s):  
Environmental Fate ◽  
Inorganic Mercury ◽  
Mercury Vapor ◽  
Brain Cell ◽  
The Body ◽  
Water Soluble ◽  
Lipid Solubility ◽  
Long Distance ◽  
Long Distance Transport ◽  
New Findings

New findings on the environmental fate of Hg indicate that lakes can be contaminated by long distance transport on mercury vapor in the atmosphere and that higher levels of Me Hg in fish are associated with acidification of lakes and with the creation of hydroelectric reservoirs. Considerable progress has been made in the understanding of the disposition and metabolism of mercury in the body. Inhaled mercury vapor rapidly enters cells in view of its lipid solubility. Inside the cell, it is oxidized by the enzyme, catalase, to inorganic divalent mercury. The latter may be the proximate toxic species. Me Hg also crosses cell membranes rapidly but, in this case, probably by forming water-soluble complexes whose structures mimic those of endogenous substrates that are transported on specific carriers. The mechanism of damage to the central nervous system by mercury vapor is still unknown. The kidney damage probably arises from the effect of inorganic mercury on immunocompetent cells causing them to produce antibodies that affect the glomerulus. The selective damage by Me Hg to specific anatomical areas of the brain and the long latent period are still unexplained. Most studies have focused on the earliest biochemical lesion, the inhibition of protein synthesis. Prenatal damage occurs in all areas of the developing brain. Cell division and abnormal neuronal migration are the processes primarily affected. The destruction of microtubules in neuronal and astrocystic cells offers a plausible explanation of the deranged cytoarchitecture. Prenatal effects such as delays in the normal development of prenatally exposed infants occur at exposures substantially lower than those associated with the onset of adult poisoning.

The Fine Structure of Phloem Cells

1985 ◽  
Vol 43 ◽  
pp. 632-635
Author(s):  
James Cronshaw
Keyword(s):  
Structural Studies ◽  
High Concentration ◽  
Long Distance ◽  
Phloem Tissue ◽  
Sieve Elements ◽  
Long Distance Transport ◽  
P Protein ◽  
Companion Cells ◽  
Electron Microscopical ◽  
Distance Transport

Long distance transport in plants takes place in phloem tissue which has characteristic cells, the sieve elements. At maturity these cells have sieve areas in their end walls with specialized perforations. They are associated with companion cells, parenchyma cells, and in some species, with transfer cells. The protoplast of the functioning sieve element contains a high concentration of sugar, and consequently a high hydrostatic pressure, which makes it extremely difficult to fix mature sieve elements for electron microscopical observation without the formation of surge artifacts. Despite many structural studies which have attempted to prevent surge artifacts, several features of mature sieve elements, such as the distribution of P-protein and the nature of the contents of the sieve area pores, remain controversial.

scholarly journals From tree to architecture: how functional morphology of arborescence connects plant biology, evolution and physics

2021 ◽  
Author(s):  
Anita Roth-Nebelsick ◽  
Tatiana Miranda ◽  
Martin Ebner ◽  
Wilfried Konrad ◽  
Christopher Traiser
Keyword(s):  
Land Plant ◽  
Plant Evolution ◽  
Ecological Niches ◽  
Long Distance ◽  
Ongoing Research ◽  
Long Distance Transport ◽  
Theoretical Approaches ◽  
Trade Offs ◽  
Interfacial Physics ◽  
Plant Water Transport

AbstractTrees are the fundamental element of forest ecosystems, made possible by their mechanical qualities and their highly sophisticated conductive tissues. The evolution of trees, and thereby the evolution of forests, were ecologically transformative and affected climate and biogeochemical cycles fundamentally. Trees also offer a substantial amount of ecological niches for other organisms, such as epiphytes, creating a vast amount of habitats. During land plant evolution, a variety of different tree constructions evolved and their constructional principles are a subject of ongoing research. Understanding the “natural construction” of trees benefits strongly from methods and approaches from physics and engineering. Plant water transport is a good example for the ongoing demand for interdisciplinary efforts to unravel form-function relationships on vastly differing scales. Identification of the unique mechanism of water long-distance transport requires a solid basis of interfacial physics and thermodynamics. Studying tree functions by using theoretical approaches is, however, not a one-sided affair: The complex interrelationships between traits, functionality, trade-offs and phylogeny inspire engineers, physicists and architects until today.

scholarly journals Leaf-derived ABA regulates rice seed development via a transporter-mediated and temperature-sensitive mechanism

2021 ◽  
Vol 7 (3) ◽  
pp. eabc8873
Author(s):  
Peng Qin ◽  
Guohua Zhang ◽  
Binhua Hu ◽  
Jie Wu ◽  
Weilan Chen ◽  
...  
Keyword(s):  
Seed Development ◽  
Starch Synthesis ◽  
Biological Significance ◽  
Grain Filling ◽  
Temperature Sensitive ◽  
Rice Seed ◽  
Dependent Manner ◽  
Long Distance ◽  
Long Distance Transport ◽  
Mechanistic Basis

Long-distance transport of the phytohormone abscisic acid (ABA) has been studied for ~50 years, yet its mechanistic basis and biological significance remain very poorly understood. Here, we show that leaf-derived ABA controls rice seed development in a temperature-dependent manner and is regulated by defective grain-filling 1 (DG1), a multidrug and toxic compound extrusion transporter that effluxes ABA at nodes and rachilla. Specifically, ABA is biosynthesized in both WT and dg1 leaves, but only WT caryopses accumulate leaf-derived ABA. Our demonstration that leaf-derived ABA activates starch synthesis genes explains the incompletely filled and floury seed phenotypes in dg1. Both the DG1-mediated long-distance ABA transport efficiency and grain-filling phenotypes are temperature sensitive. Moreover, we extended these mechanistic insights to other cereals by observing similar grain-filling defects in a maize DG1 ortholog mutant. Our study demonstrates that rice uses a leaf-to-caryopsis ABA transport–based mechanism to ensure normal seed development in response to variable temperatures.

scholarly journals PSIX-33 Docosahexaenoic Acid (DHA) but not Eicosapentaenoic Acid (EPA) induces the trans-differentiation of C2C12 into white-like adipocytes phenotype

2020 ◽  
Vol 98 (Supplement_4) ◽  
pp. 309-310
Author(s):  
Yan Huang ◽  
Saeed Ghnaimawi ◽  
Yongjie Wang ◽  
Shilei Zhang ◽  
Jamie Baum
Keyword(s):  
Mitochondrial Biogenesis ◽  
Cultured Cells ◽  
Adipogenic Differentiation ◽  
The Body ◽  
C2c12 Cells ◽  
Brown Adipocyte ◽  
Marker Genes ◽  
Induction Medium ◽  
Spare Capacity ◽  
Epa And Dha

Abstract Muscle-derived stem cells (MDSCs, or myoblasts) play an important role in myotubes regeneration. However, these cells can differentiate into adipocytes once exposed to EPA and DHA, which are highly suggested during pregnancy. The objective of this study aims at determining the effect of isolated EPA and DHA on C2C12 cells undergoing white and brown adipogenic differentiation. Confluent cultured cells were treated with white and brown adipocyte induction medium (WIM and BIM respectively) with 50µM EPA and 50µM DHA separately. DHA treated groups differentiated into white-like adipocyte by down-regulating the expression of myogenic genes such as MyoD, MyoG, and Mrf4; but promoted white adipocyte marker genes(P < 0.05). Moreover, cells treated with WIM and DHA exhibited a decrease in mitochondrial biogenesis through suppressing PGC1a and TFAM expression (P < 0.05). Also, DHA promoted the expression of lipolysis regulating genes. DHA impaired C2C12 cells browning through reducing the mitochondrial biogenesis by significantly suppressing the expression of COX7a1, PGC1a, and UCP3 genes (P < 0.05). DHA treated groups showed an increased accumulation of lipid droplets and suppressed maximal mitochondrial respiration and spare capacity. EPA treatment reduced myogenesis regulating genes (P < 0.05) but did not affect adipogenic genes (P >0.05). Likewise, EPA suppressed the expression of WAT signature genes (P < 0.05), indicating its antagonism to DHA. EPA and WIM treatment suppressed the expression of TFAM and PGC1a, but did not affect PGC1a protein level. Although mitochondrial biogenic gene expression was reduced in EPA and BIDM treated group, no changes in mitochondrial function were observed. EPA supplementation did not affect the differential route of C2C12 into brown adipocytes. To conclude, EPA and DHA may similarly affect the integrity of muscle tissue, but DHA is a potent adipogenic and lipogenic factor that can change the metabolic profile of the body by increasing intramuscular fat.

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