Spatiotemporal auxin distribution in Arabidopsis tissues is regulated by anabolic and catabolic reactions under long-term ammonium stress

Abstract Background The plant hormone auxin is a major coordinator of plant growth and development in response to diverse environmental signals, including nutritional conditions. Sole ammonium (NH4+) nutrition is one of the unique growth-suppressing conditions for plants. Therefore, the quest to understand NH4+-mediated developmental defects led us to analyze auxin metabolism. Results Indole-3-acetic acid (IAA), the most predominant natural auxin, accumulates in the leaves and roots of mature Arabidopsis thaliana plants grown on NH4+, but not in the root tips. We found changes at the expressional level in reactions leading to IAA biosynthesis and deactivation in different tissues. Finally, NH4+ nutrition would facilitate the formation of inactive oxidized IAA as the final product. Conclusions NH4+-mediated accelerated auxin turnover rates implicate transient and local IAA peaks. A noticeable auxin pattern in tissues correlates with the developmental adaptations of the short and highly branched root system of NH4+-grown plants. Therefore, the spatiotemporal distribution of auxin might be a root-shaping signal specific to adjust to NH4+-stress conditions.

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Auxin-Induced SaARF4 Downregulates SaACO4 to Inhibit Lateral Root Formation in Sedum alfredii Hance

International Journal of Molecular Sciences ◽

10.3390/ijms22031297 ◽

2021 ◽

Vol 22 (3) ◽

pp. 1297

Author(s):

Dong Xu ◽

Zhuchou Lu ◽

Guirong Qiao ◽

Wenmin Qiu ◽

Longhua Wu ◽

...

Keyword(s):

Lateral Root ◽

Ethylene Biosynthesis ◽

Luciferase Assay ◽

Sedum Alfredii ◽

Ethylene Synthesis ◽

Root Tips ◽

Sedum Alfredii Hance ◽

Auxin Distribution ◽

Distribution Mode ◽

High Level

Lateral root (LR) formation promotes plant resistance, whereas high-level ethylene induced by abiotic stress will inhibit LR emergence. Considering that local auxin accumulation is a precondition for LR generation, auxin-induced genes inhibiting ethylene synthesis may thus be important for LR development. Here, we found that auxin response factor 4 (SaARF4) in Sedum alfredii Hance could be induced by auxin. The overexpression of SaARF4 decreased the LR number and reduced the vessel diameters. Meanwhile, the auxin distribution mode was altered in the root tips and PIN expression was also decreased in the overexpressed lines compared with the wild-type (WT) plants. The overexpression of SaARF4 could reduce ethylene synthesis, and thus, the repression of ethylene production decreased the LR number of WT and reduced PIN expression in the roots. Furthermore, the quantitative real-time PCR, chromatin immunoprecipitation sequencing, yeast one-hybrid, and dual-luciferase assay results showed that SaARF4 could bind the promoter of 1-aminocyclopropane-1-carboxylate oxidase 4 (SaACO4), associated with ethylene biosynthesis, and could downregulate its expression. Therefore, we concluded that SaARF4 induced by auxin can inhibit ethylene biosynthesis by repressing SaACO4 expression, and this process may affect auxin transport to delay LR development.

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Quantitative analysis of the CD8 + T–cell response to readily eliminated and persistent viruses

Philosophical Transactions of the Royal Society B Biological Sciences ◽

10.1098/rstb.2000.0647 ◽

2000 ◽

Vol 355 (1400) ◽

pp. 1093-1101 ◽

Cited By ~ 29

Author(s):

P. C. Doherty ◽

J. M. Riberdy ◽

G. T. Belz

Keyword(s):

T Cells ◽

T Cell ◽

Influenza A ◽

Flow Cytometric Analysis ◽

T Cell Response ◽

Basic Question ◽

Cell Mediated Immunity ◽

Specific Response ◽

Turnover Rates

The recent development of techniques for the direct staining of peptide–specific CD8 + T cells has revolutionized the analysis of cell–mediated immunity (CMI) in virus infections. This approach has been used to quantify the acute and long–term consequences of infecting laboratory mice with the readily eliminated influenza A viruses (fluA) and a persistent γherpesvirus (γHV). It is now, for the first time, possible to work with real numbers in the analysis of CD8 + T CMI, and to define various characteristics of the responding lymphocytes both by direct flow cytometric analysis and by sorting for further in vitro manipulation. Relatively little has yet been done from the latter aspect, though we are rapidly accumulating a mass of numerical data. The acute, antigen–driven phases of the fluA and γHV–specific response look rather similar, but CD8 + T–cell numbers are maintained in the long term at a higher ‘set point’ in the persistent infection. Similarly, these ‘memory’ T cells continue to divide at a much greater rate in the γHV–infected mice. New insights have also been generated on the nature of the recall response following secondary challenge in both experimental systems, and the extent of protection conferred by large numbers of virus–specific CD8 + T cells has been determined. However, there are still many parameters that have received little attention, partly because they are difficult to measure. These include the rate of antigen–specific CD8 + T–cell loss, the extent of the lymphocyte ‘diaspora’ to other tissues, and the diversity of functional characteristics, turnover rates, clonal life spans and recirculation profiles. The basic question for immunologists remains how we reconcile the extraordinary plasticity of the immune system with the mechanisms that maintain a stable milieu interieur. This new capacity to quantify CD8 + T–cell responses in readily manipulated mouse models has obvious potential for illuminating homeostatic control, particularly if the experimental approaches to the problem are designed in the context of appropriate predictive models.

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The ectopic expression of Arabidopsis glucosyltransferase UGT74D1 affects leaf positioning through modulating indole-3-acetic acid homeostasis

Scientific Reports ◽

10.1038/s41598-021-81016-x ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Shanghui Jin ◽

Bingkai Hou ◽

Guizhi Zhang

Keyword(s):

Acetic Acid ◽

Ectopic Expression ◽

Leaf Angle ◽

Kinase Substrate ◽

Auxin Distribution ◽

Leaf Tissues ◽

Photosynthesis Efficiency ◽

Indole 3 Acetic Acid

AbstractLeaf angle is an important agronomic trait affecting photosynthesis efficiency and crop yield. Although the mechanisms involved in the leaf angle control are intensively studied in monocots, factors contribute to the leaf angle in dicots are largely unknown. In this article, we explored the physiological roles of an Arabidopsis glucosyltransferase, UGT74D1, which have been proved to be indole-3-acetic acid (IAA) glucosyltransferase in vitro. We found that UGT74D1 possessed the enzymatic activity toward IAA glucosylation in vivo and its expression was induced by auxins. The ectopically expressed UGT74D1 obviously reduced the leaf angle with an altered IAA level, auxin distribution and cell size in leaf tissues. The expression of several key genes involved in the leaf shaping and leaf positioning, including PHYTOCHROME KINASE SUBSTRATE (PKS) genes and TEOSINTE BRANCHED1, CYCLOIDEA, and PCF (TCP) genes, were dramatically changed by ectopic expression of UGT74D1. In addition, clear transcription changes of YUCCA genes and other auxin related genes can be observed in overexpression lines. Taken together, our data indicate that glucosyltransferase UGT74D1 could affect leaf positioning through modulating auxin homeostasis and regulating transcription of PKS and TCP genes, suggesting a potential new role of UGT74D1 in regulation of leaf angle in dicot Arabidopsis.

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Biochemical and Genetic Bases of Indole-3-Acetic Acid (Auxin Phytohormone) Degradation by the Plant-Growth-Promoting Rhizobacterium Paraburkholderia phytofirmans PsJN

Applied and Environmental Microbiology ◽

10.1128/aem.01991-16 ◽

2016 ◽

Vol 83 (1) ◽

Cited By ~ 19

Author(s):

Raúl Donoso ◽

Pablo Leiva-Novoa ◽

Ana Zúñiga ◽

Tania Timmermann ◽

Gonzalo Recabarren-Gajardo ◽

...

Keyword(s):

Energy Source ◽

Gene Regulation ◽

Acetic Acid ◽

Plant Growth ◽

Plant Hormone ◽

Content Type ◽

Gene Functions ◽

Plant Growth Promoting ◽

Growth Promoting ◽

Indole 3 Acetic Acid

ABSTRACT Several bacteria use the plant hormone indole-3-acetic acid (IAA) as a sole carbon and energy source. A cluster of genes (named iac) encoding IAA degradation has been reported in Pseudomonas putida 1290, but the functions of these genes are not completely understood. The plant-growth-promoting rhizobacterium Paraburkholderia phytofirmans PsJN harbors iac gene homologues in its genome, but with a different gene organization and context than those of P. putida 1290. The iac gene functions enable P. phytofirmans to use IAA as a sole carbon and energy source. Employing a heterologous expression system approach, P. phytofirmans iac genes with previously undescribed functions were associated with specific biochemical steps. In addition, two uncharacterized genes, previously unreported in P. putida and found to be related to major facilitator and tautomerase superfamilies, are involved in removal of an IAA metabolite called dioxindole-3-acetate. Similar to the case in strain 1290, IAA degradation proceeds through catechol as intermediate, which is subsequently degraded by ortho-ring cleavage. A putative two-component regulatory system and a LysR-type regulator, which apparently respond to IAA and dioxindole-3-acetate, respectively, are involved in iac gene regulation in P. phytofirmans. These results provide new insights about unknown gene functions and complex regulatory mechanisms in IAA bacterial catabolism. IMPORTANCE This study describes indole-3-acetic acid (auxin phytohormone) degradation in the well-known betaproteobacterium P. phytofirmans PsJN and comprises a complete description of genes, some of them with previously unreported functions, and the general basis of their gene regulation. This work contributes to the understanding of how beneficial bacteria interact with plants, helping them to grow and/or to resist environmental stresses, through a complex set of molecular signals, in this case through degradation of a highly relevant plant hormone.

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Greater soil carbon stocks and faster turnover rates with increasing agricultural productivity

SOIL ◽

10.5194/soil-3-1-2017 ◽

2017 ◽

Vol 3 (1) ◽

pp. 1-16 ◽

Cited By ~ 21

Author(s):

Jonathan Sanderman ◽

Courtney Creamer ◽

W. Troy Baisden ◽

Mark Farrell ◽

Stewart Fallon

Keyword(s):

Organic Matter ◽

Soil Carbon ◽

Sugar Content ◽

Bulk Composition ◽

Agricultural Productivity ◽

Carbon Stocks ◽

Decay Rates ◽

Turnover Rates ◽

Soil Carbon Stocks

Abstract. Devising agricultural management schemes that enhance food security and soil carbon levels is a high priority for many nations. However, the coupling between agricultural productivity, soil carbon stocks and organic matter turnover rates is still unclear. Archived soil samples from four decades of a long-term crop rotation trial were analyzed for soil organic matter (SOM) cycling-relevant properties: C and N content, bulk composition by nuclear magnetic resonance (NMR) spectroscopy, amino sugar content, short-term C bioavailability assays, and long-term C turnover rates by modeling the incorporation of the bomb spike in atmospheric 14C into the soil. After > 40 years under consistent management, topsoil carbon stocks ranged from 14 to 33 Mg C ha−1 and were linearly related to the mean productivity of each treatment. Measurements of SOM composition demonstrated increasing amounts of plant- and microbially derived SOM along the productivity gradient. Under two modeling scenarios, radiocarbon data indicated overall SOM turnover time decreased from 40 to 13 years with increasing productivity – twice the rate of decline predicted from simple steady-state models or static three-pool decay rates of measured C pool distributions. Similarly, the half-life of synthetic root exudates decreased from 30.4 to 21.5 h with increasing productivity, indicating accelerated microbial activity. These findings suggest that there is a direct feedback between accelerated biological activity, carbon cycling rates and rates of carbon stabilization with important implications for how SOM dynamics are represented in models.

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Differentiation of urban and rural populations of Kherson region on the frequency of congenital malformations and reproductive losses

Reports of Vinnytsia National Medical University ◽

10.31393/reports-vnmedical-2018-22(1)-02 ◽

2018 ◽

Vol 22 (1) ◽

pp. 10-13

Author(s):

O.G. Lanovenko

Keyword(s):

Birth Defects ◽

Congenital Malformations ◽

Rural Populations ◽

Developmental Defects ◽

Statistical Computation ◽

Reproductive Losses ◽

Hereditary Component ◽

Regional Medical ◽

The Impact

The problem of differential prevalence of congenital malformation and reproductive losses in Ukrainian populations becomes especially relevant in the context of increasing the impact of environmental and genetic and demographic factors that can influence their gene pool. The purpose of the study is to determine, during long-term monitoring, the statistically significant differences between the rural populations of Kherson oblast on the incidence of birth defects, involuntary miscarriages and stillbirths, in order to further identify the causes of detected heterogeneity. In calculating the frequency of these indicators in urban and rural populations, the materials of the regional medical-statistical register (medical form 21, 13, 49) are used. The statistical computation of the results obtained (calculation of confidence intervals and the reliability of the differences) was carried out using STATISTICA and Microsoft Excel 9-2000 programs. It has been established that there are significant differences between urban and rural populations in the prevalence of congenital malformations and reproductive losses. In Kherson, for the period of 2000–2013, the average incidence of developmental defects (37.8±11.3‰) and stillbirths (8.2±1.1‰) significantly exceeded similar rates in rural populations (respectively 23.9±1.4‰ and 4.8±0.6‰). However, in rural populations, the incidence of involuntary miscarriages was significantly higher (31.2 ± 1.9 ‰) than in the oblast center (18.9 ± 2.1 ‰). In addition, according to these indicators there is a significant differentiation between rural populations. The prevalence of birth defects in infants in the region is due to an increase in the frequency of “model” defects (r=0.69, p<0.05), which have a significant hereditary component. It was found that in the urban Kherson population, the relatively high frequency of postnatal violations testifies to the weakening of the “sifting” effect of natural selection. On the contrary, selection in rural populations eliminates most of the non-viable embryos in the early stages of pregnancy, as evidenced by the relatively high prevalence of involuntary miscarriages. In the long term, it is necessary to establish the correlation between the indices of the incidence of congenital and hereditary pathology in populations and the parameters of their genetic and demographic structure.

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Label-Free Study of the Global Cell Behavior during Exposure to Environmental Radiofrequency Fields in the Presence or Absence of Pro-Apoptotic or Pro-Autophagic Treatments

International Journal of Molecular Sciences ◽

10.3390/ijms23020658 ◽

2022 ◽

Vol 23 (2) ◽

pp. 658

Author(s):

Alexandre Joushomme ◽

André Garenne ◽

Mélody Dufossée ◽

Rémy Renom ◽

Hermanus Johannes Ruigrok ◽

...

Keyword(s):

Mobile Communications ◽

Cellular Response ◽

Continuous Wave ◽

Digital Holographic Microscopy ◽

Label Free ◽

Environmental Signals ◽

Chemical Treatments ◽

Rf Exposure ◽

Universal Mobile Telecommunications System

It remains controversial whether exposure to environmental radiofrequency signals (RF) impacts cell status or response to cellular stress such as apoptosis or autophagy. We used two label-free techniques, cellular impedancemetry and Digital Holographic Microscopy (DHM), to assess the overall cellular response during RF exposure alone, or during co-exposure to RF and chemical treatments known to induce either apoptosis or autophagy. Two human cell lines (SH-SY5Y and HCT116) and two cultures of primary rat cortex cells (astrocytes and co-culture of neurons and glial cells) were exposed to RF using an 1800 MHz carrier wave modulated with various environmental signals (GSM: Global System for Mobile Communications, 2G signal), UMTS (Universal Mobile Telecommunications System, 3G signal), LTE (Long-Term Evolution, 4G signal, and Wi-Fi) or unmodulated RF (continuous wave, CW). The specific absorption rates (S.A.R.) used were 1.5 and 6 W/kg during DHM experiments and ranged from 5 to 24 W/kg during the recording of cellular impedance. Cells were continuously exposed for three to five consecutive days while the temporal phenotypic signature of cells behavior was recorded at constant temperature. Statistical analysis of the results does not indicate that RF-EMF exposure impacted the global behavior of healthy, apoptotic, or autophagic cells, even at S.A.R. levels higher than the guidelines, provided that the temperature was kept constant.

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Quantitative effects of environmental variation on stomatal anatomy and gas exchange in a grass model

10.1101/2021.11.10.468085 ◽

2021 ◽

Author(s):

Tiago DG Nunes ◽

Magdalena W Slawinska ◽

Heike Lindner ◽

Michael T Raissig

Keyword(s):

Gas Exchange ◽

Anatomical Variation ◽

Brachypodium Distachyon ◽

Carbon Assimilation ◽

Light Response ◽

Gas Analysis ◽

Environmental Signals ◽

Grass Model ◽

Kinetics Of

Stomata are cellular pores on the leaf epidermis that allow plants to regulate carbon assimilation and water loss. Stomata integrate environmental signals to regulate pore apertures and optimize gas exchange to fluctuating conditions. Here, we quantified intraspecific plasticity of stomatal gas exchange and anatomy in response to seasonal variation in Brachypodium distachyon. Over the course of two years we (i) used infrared gas analysis to assess light response kinetics of 120 Bd21-3 wild-type individuals in an environmentally fluctuating greenhouse and (ii) microscopically determined the seasonal variability of stomatal anatomy in a subset of these plants. We observed systemic environmental effects on gas exchange measurements and remarkable intraspecific plasticity of stomatal anatomical traits. To reliably link anatomical variation to gas exchange, we adjusted anatomical gsmax calculations for grass stomatal morphology. We propose that systemic effects and variability in stomatal anatomy should be accounted for in long-term gas exchange studies.

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Annual variations in the microflora of some varieties of Finnish malting barley

Agricultural and Food Science ◽

10.23986/afsci.72618 ◽

1995 ◽

Vol 4 (4) ◽

pp. 407-418

Author(s):

Tapani Tuominen ◽

Heikki Rosenqvist

Keyword(s):

Plant Hormone ◽

Growing Season ◽

Fungal Species ◽

Consistent Difference ◽

Malting Barley ◽

Microbial Infection ◽

Microbial Counts ◽

Annual Variations ◽

Average Rainfall ◽

Indole 3 Acetic Acid

Three major Finnish malting barley varieties were studied for annual variations in the incidence of seed-derived fungi, bacteria and actinomycetes. In 1990-1992, 114 characterized fungal, 59 uncharacterized bacterial and 12 uncharacterized actinomycetal isolates were extracted from samples of seed intended for use in malting. When the yield of the plant hormone, indole-3-acetic acid (lAA), from enriched microbial cultures was weighed against the microbial biomass and the endogenous lAA concentration of the barley harvests, it was concluded that potential exists for bacterial lAA production in biologically significant amounts, given some minor annual variations. As expected from the average rainfall and temperature during the growing season, microbial counts in all cultivars were highest in 1992. Most of the fungal species found were of saphrophytic character, and field fungi were dominant in the samples. On the whole, microbial counts and spectra in all samples confirmed that each harvest of all cultivars was of good vigour and well suited for malting purposes. Strains of plant pathogenic character included species of Septoria nodorum (Berk) Berk, Drechlera teres (Sacc) Subraim & Jain, D. sorokiniana (Sacc) Subram & Jain and D. graminea (Rab.) Shoem. A consistent difference was noted in the microbial infection severities of the cultivars.

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