Survival of Plants During Short-Term BOA-OH Exposure: ROS Related Gene Expression and Detoxification Reactions Are Accompanied With Fast Membrane Lipid Repair in Root Tips

AbstractFor the characterization of BOA-OH insensitive plants, we studied the time-dependent effects of the benzoxazolinone-4/5/6/7-OH isomers on maize roots. Exposure of Zea mays seedlings to 0.5 mM BOA-OH elicits root zone-specific reactions by the formation of dark rings and spots in the zone of lateral roots, high catalase activity on root hairs, and no visible defense reaction at the root tip. We studied BOA-6-OH- short-term effects on membrane lipids and fatty acids in maize root tips in comparison to the benzoxazinone-free species Abutilon theophrasti Medik. Decreased contents of phosphatidylinositol in A. theophrasti and phosphatidylcholine in maize were found after 10–30 min. In the youngest tissue, α-linoleic acid (18:2), decreased considerably in both species and recovered within one hr. Disturbances in membrane phospholipid contents were balanced in both species within 30–60 min. Triacylglycerols (TAGs) were also affected, but levels of maize diacylglycerols (DAGs) were almost unchanged, suggesting a release of fatty acids for membrane lipid regeneration from TAGs while resulting DAGs are buildings blocks for phospholipid reconstitution, concomitant with BOA-6-OH glucosylation. Expression of superoxide dismutase (SOD2) and of ER-bound oleoyl desaturase (FAD2-2) genes were contemporaneously up regulated in contrast to the catalase CAT1, while CAT3 was arguably involved at a later stage of the detoxification process. Immuno-responses were not elicited in short-terms, since the expression of NPR1, POX12 were barely affected, PR4 after 6 h with BOA-4/7-OH and PR1 after 24 h with BOA-5/6-OH. The rapid membrane recovery, reactive oxygen species, and allelochemical detoxification may be characteristic for BOA-OH insensitive plants.

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Histopathology of Pythium infected strawberry roots

Canadian Journal of Botany ◽

10.1139/b72-135 ◽

1972 ◽

Vol 50 (5) ◽

pp. 1091-1096 ◽

Cited By ~ 13

Author(s):

S. Nemec

Keyword(s):

Root Hairs ◽

Petri Dish ◽

Root Tip ◽

Test Results ◽

Root Tips ◽

Cortical Cells ◽

Pythium Irregulare ◽

Infected Root ◽

Cortical Infection ◽

Host Parasite

Host–parasite interactions between eight Pythium species, previously isolated from necrotic strawberry root tissue, and Fragaria × ananassa Duch. runner plant main roots were studied. When excised roots were placed in water on petri dish cultures, P. rostratum and P. hypogenum infection was limited to the root tip epidermis. Pythium irregulare, P. perniciosum, P. dissotocum, P. sylvaticum, P. ultimum, and unidentified isolate 1E penetrated the epidermis several centimeters along the zone of maturation. Penetration occurred most frequently through root hairs by hyphae; resulting infections usually stopped in the epidermis or adjacent cortex, and here hyphae formed sporangium-like structures, oogonia, and oospores. Extensive cortical infection by hyphae was primarily limited to the zone of elongation. Extent of epidermal and cortical infection in roots grown in soil with P. irregulare, P. dissotocum, and P. sylvaticum was similar to petri dish test results. Stelar infection by P. sylvaticum and P. dissotocum occurred mainly in phloem cells, but did not advance far into the region of maturation. Numerous oogonia formed in infected steles and usually in adjacent cortical cells. Infected roots ranged from a white to grey, water-soaked color. Extensively infected root tips typically were unhealthy, succulent, and thin.

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Tissue growth constrains root organ outlines into an isometrically scalable shape

Development ◽

10.1242/dev.196253 ◽

2021 ◽

Vol 148 (4) ◽

pp. dev196253

Author(s):

Motohiro Fujiwara ◽

Tatsuaki Goh ◽

Satoru Tsugawa ◽

Keiji Nakajima ◽

Hidehiro Fukaki ◽

...

Keyword(s):

Plant Root ◽

Lateral Roots ◽

Time Lapse ◽

Tissue Growth ◽

Root Tip ◽

Root Tips ◽

Developmental Constraints ◽

Primary Roots ◽

Catenary Curve ◽

Expansion Force

ABSTRACTOrgan morphologies are diverse but also conserved under shared developmental constraints among species. Any geometrical similarities in the shape behind diversity and the underlying developmental constraints remain unclear. Plant root tip outlines commonly exhibit a dome shape, which likely performs physiological functions, despite the diversity in size and cellular organization among distinct root classes and/or species. We carried out morphometric analysis of the primary roots of ten angiosperm species and of the lateral roots (LRs) of Arabidopsis, and found that each root outline was isometrically scaled onto a parameter-free catenary curve, a stable structure adopted for arch bridges. Using the physical model for bridges, we analogized that localized and spatially uniform occurrence of oriented cell division and expansion force the LR primordia (LRP) tip to form a catenary curve. These growth rules for the catenary curve were verified by tissue growth simulation of developing LRP development based on time-lapse imaging. Consistently, LRP outlines of mutants compromised in these rules were found to deviate from catenary curves. Our analyses demonstrate that physics-inspired growth rules constrain plant root tips to form isometrically scalable catenary curves.

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Galactolipid and Phospholipid Profile and Proteome Alterations in Soybean Leaves at the Onset of Salt Stress

Frontiers in Plant Science ◽

10.3389/fpls.2021.644408 ◽

2021 ◽

Vol 12 ◽

Author(s):

Ailin Liu ◽

Zhixia Xiao ◽

Zhili Wang ◽

Hon-Ming Lam ◽

Mee-Len Chye

Keyword(s):

Salt Stress ◽

Membrane Lipids ◽

Membrane Lipid ◽

Salt Treatment ◽

Short Term ◽

Lipid Profiling ◽

Soybean Seedlings ◽

Proteomic Data ◽

Before And After ◽

Soybean Leaves

Salinity is a major environmental factor that constrains soybean yield and grain quality. Given our past observations using the salt-sensitive soybean (Glycine max [L.] Merr.) accession C08 on its early responses to salinity and salt-induced transcriptomic modifications, the aim of this study was to assess the lipid profile changes in this cultivar before and after short-term salt stress, and to explore the adaptive mechanisms underpinning lipid homeostasis. To this end, lipid profiling and proteomic analyses were performed on the leaves of soybean seedlings subjected to salt treatment for 0, 0.5, 1, and 2 h. Our results revealed that short-term salt stress caused dynamic lipid alterations resulting in recycling for both galactolipids and phospholipids. A comprehensive understanding of membrane lipid adaption following salt treatment was achieved by combining time-dependent lipidomic and proteomic data. Proteins involved in phosphoinositide synthesis and turnover were upregulated at the onset of salt treatment. Salinity-induced lipid recycling was shown to enhance jasmonic acid and phosphatidylinositol biosyntheses. Our study demonstrated that salt stress resulted in a remodeling of membrane lipid composition and an alteration in membrane lipids associated with lipid signaling and metabolism in C08 leaves.

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Supra-physiological levels of Gibberellins/DELLAs alter the patterning, morphology and abundance of root hairs in root tips of A. thaliana seedlings

10.1101/2021.07.15.452505 ◽

2021 ◽

Author(s):

Iva McCarthy-Suarez

Keyword(s):

Gene Expression ◽

Cell Fate ◽

Epidermal Cell ◽

Root Hair ◽

Root Hairs ◽

Root Tip ◽

Spatial Patterning ◽

Root Tips ◽

Root Epidermis

In spite of the known role of gibberellins (GAs), and of their antagonistic proteins, the DELLAs, in leaf hair production, no investigations, however, have assessed their hypothetical function in the production of root hairs. To this aim, the effects of supra-physiological levels of GAs/DELLAs on the spatial patterning of gene expression of the root hair (CPC) and root non-hair (GL2, EGL3 and WER) epidermal cell fate markers, as well as on the distribution, morphology and abundance of root hairs, were studied in root tips of 5-day-old A. thaliana seedlings. Results showed that excessive levels of GAs/DELLAs impaired the spatial patterning of gene expression of the root hair/non-hair epidermal cell fate markers, as well as the arrangement, shape and frequency of root hairs, giving rise to ectopic hairs and ectopic non-hairs, two-haired cells, two-tipped hairs, branched hairs, longer and denser hairs near the root tip under excessive DELLAs, and shorter and scarcer hairs near the root tip under excessive GAs. However, when the gai-1 (GA-insensitive-1) DELLA mutant protein was specifically over-expressed at the root epidermis, no changes in the patterning or abundance of root hairs occurred. Thus, these results suggest that, in seedlings of A. thaliana, the GAs/DELLAs might have a role in regulating the patterning, morphology and abundance of root hairs by acting from the sub-epidermal tissues of the root.

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Revealing Further Insights on Chilling Injury of Postharvest Bananas by Untargeted Lipidomics

Foods ◽

10.3390/foods9070894 ◽

2020 ◽

Vol 9 (7) ◽

pp. 894 ◽

Cited By ~ 1

Author(s):

Juan Liu ◽

Qingxin Li ◽

Junjia Chen ◽

Yueming Jiang

Keyword(s):

Fatty Acids ◽

Low Temperature ◽

Unsaturated Fatty Acids ◽

Membrane Lipids ◽

Saturated Fatty Acids ◽

Chilling Injury ◽

Membrane Damage ◽

Membrane Lipid ◽

Banana Fruit ◽

Control Fruit

Chilling injury is especially prominent in postharvest bananas stored at low temperature below 13 °C. To elucidate better the relationship between cell membrane lipids and chilling injury, an untargeted lipidomics approach using ultra-performance liquid chromatography–mass spectrometry was conducted. Banana fruit were stored at 6 °C for 0 (control) and 4 days and then sampled for lipid analysis. After 4 days of storage, banana peel exhibited a marked chilling injury symptom. Furthermore, 45 lipid compounds, including glycerophospholipids, saccharolipids, and glycerolipids, were identified with significant changes in peel tissues of bananas stored for 4 days compared with the control fruit. In addition, higher ratio of digalactosyldiacylglycerol (DGDG) to monogalactosyldiacylglycerol (MGDG) and higher levels of phosphatidic acid (PA) and saturated fatty acids but lower levels of phosphatidylcholine (PC), phosphatidylethanolamine (PE), and unsaturated fatty acids were observed in banana fruit with chilling injury in contrast to the control fruit. Meanwhile, higher activities of phospholipase D (PLD) and lipoxygenase (LOX) were associated with significantly upregulated gene expressions of MaPLD1 and MaLOX2 and higher malondialdehyde (MDA) content in chilling injury-related bananas. In conclusion, our study indicated that membrane lipid degradation resulted from reduced PC and PE, but accumulated PA, while membrane lipid peroxidation resulted from the elevated saturation of fatty acids, resulting in membrane damage which subsequently accelerated the chilling injury occurrence of banana fruit during storage at low temperature.

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Membrane lipids and sodium pumps of cattle and crocodiles: an experimental test of the membrane pacemaker theory of metabolism

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.00549.2003 ◽

2004 ◽

Vol 287 (3) ◽

pp. R633-R641 ◽

Cited By ~ 23

Author(s):

B. J. Wu ◽

A. J. Hulbert ◽

L. H. Storlien ◽

P. L. Else

Keyword(s):

Fatty Acids ◽

Lipid Composition ◽

Sodium Pump ◽

Bos Taurus ◽

Membrane Lipids ◽

Membrane Lipid ◽

Sodium Pumps ◽

Lipid Source ◽

Microsomal Membranes ◽

Membrane Pacemaker

The influence of membrane lipid composition on the molecular activity of a major membrane protein (the sodium pump) was examined as a test of the membrane pacemaker theory of metabolism. Microsomal membranes from the kidneys of cattle (Bos taurus) and crocodiles (Crocodylus porosus) were found to possess similar sodium pump concentrations, but cattle membranes showed a four- to fivefold higher enzyme (Na+-K+-ATPase) activity when measured at 37°C. The molecular activity of the sodium pumps (ATP/min) from both species was fully recoverable when delipidated pumps were reconstituted with membrane from the original source (same species). The results of experiments involving species membrane crossovers showed cattle sodium pump molecular activity to progressively decrease from 3,245 to 1,953 ( P < 0.005) to 1,031 ( P < 0.003) ATP/min when subjected to two cycles of delipidation and reconstitution with crocodile membrane as a lipid source. In contrast, the molecular activity of crocodile sodium pumps progressively increased from 729 to 908 ( P < 0.01) to 1,476 ( P = 0.01) ATP/min when subjected to two cycles of delipidation and reconstitution with cattle membrane as a lipid source. The lipid composition of the two membrane preparations showed similar levels of saturated (∼31–34%) and monounsaturated (∼23–25%) fatty acids. Cattle membrane had fourfold more n-3 polyunsaturated fatty acids (11.2 vs. 2.9%) but had a reduced n-6 polyunsaturate content (29 vs. 43%). The results support the membrane pacemaker theory of metabolism and suggest membrane lipids and their polyunsaturates play a significant role in determining the molecular activity of the sodium pump.

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The modification of method of the artificial inoculation of sunflower seedlings with Phoma rot pathogen in the laboratory conditions to identify the colonizing activity of strains-producer of microbiopreparations

Oil Crops Scientific and technical bulletin of All-Russian Research Insitute of Oil Crops by the name of Pustovoit V S ◽

10.25230/2412-608x-2020-4-184-52-56 ◽

2020 ◽

Vol 4 (184) ◽

pp. 52-56

Author(s):

L.V. Maslienko ◽

◽

A.Kh. Voronkova ◽

L.A. Datsenko ◽

E.A. Efimtseva ◽

...

Keyword(s):

Early Stage ◽

Lateral Roots ◽

Artificial Inoculation ◽

Root Tip ◽

Root Tips ◽

Laboratory Conditions ◽

Oil Crops ◽

Russian Research Institute ◽

The Difference ◽

Intensive Development

We carried the work in the biomethod laboratory of the crop management department of V.S. Pustovoit All-Russian Research Institute of Oil Crops. We modified the method of artificial inoculation of sunflower seedlings with a pathogen in a laboratory conditions for the secondary screening of antagonist strains from the collection of the biomethod laboratory to Phoma rot pathogen. We developed a five-point scale for evaluation of affection degree of sunflower seedlings by Phoma rot pathogen: 0 points – healthy seedlings; 1 point – darkening of the root tip, intensive development of lateral roots; 2 points – darkening of the root by a third or up to the middle, but intensive development of lateral roots; 3 points – necking of rot in the middle of the root or between the hypocotyl and the root, lateral roots are poorly developed; 4 points – root rotting to the middle or necking between the hypocotyl and the root, but intensive development of lateral roots; 5 points – complete rotting of the root, lateral roots are poorly developed or absent; 1-3 – viable seedlings; 4-5 – non-viable seedlings. The optimal period of exposure of the root tips of sunflower seedlings to the pathogen colony equal to 3 hours develops an average background of infection with the pathogen (60.0 %) already on the first day, at which it is possible to evaluate at an early stage the difference between the variants by the colonizing activity of laboratory samples of microbiological preparations.

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Excretion of triacylglycerol as a matrix lipid facilitating apoplastic accumulation of a lipophilic metabolite shikonin.

10.1101/2021.08.04.455005 ◽

2021 ◽

Author(s):

Kanade Tatsumi ◽

Takukji Ichino ◽

Natsumi Isaka ◽

Akifumi Sugiyama ◽

Yozo Okazaki ◽

...

Keyword(s):

Fatty Acids ◽

Cell Death ◽

Membrane Lipids ◽

Saturated Fatty Acids ◽

Membrane Lipid ◽

Lithospermum Erythrorhizon ◽

Cell Secretion ◽

Oil Droplets

Plants produce a large variety of lipophilic metabolites, many of which are secreted by cells and accumulated in apoplasts. The mechanism of secretion remains largely unknown, because hydrophobic metabolites, which may form oil droplets or crystals in cytosol, inducing cell death, cannot be directly secreted by transporters. Moreover, some secondary metabolic lipids react with cytosolic components leading to their decomposition. Lipophilic metabolites should thus be solubilized by matrix lipids and compartmentalized by membrane lipids. The mechanism of lipophilic metabolite secretion was assessed using shikonin, a red naphthoquinone lipid, in Lithospermum erythrorhizon. Cell secretion of shikonin also involved the secretion of about 30% of triacylglycerol (TAG), composed predominantly of saturated fatty acids. Shikonin production was associated with the induction of large amounts of the membrane lipid phosphatidylcholine. Together with in vitro reconstitution, these findings suggest a novel role for TAG as a matrix lipid for the secretion of lipophilic metabolites.

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Nitrate and glutamate sensing by plant roots

Biochemical Society Transactions ◽

10.1042/bst0330283 ◽

2005 ◽

Vol 33 (1) ◽

pp. 283-286 ◽

Cited By ~ 36

Author(s):

S. Filleur ◽

P. Walch-Liu ◽

Y. Gan ◽

B.G. Forde

Keyword(s):

Root Growth ◽

Lateral Root ◽

Lateral Roots ◽

Primary Root ◽

Root Tip ◽

Root Tips ◽

Environmental Signals ◽

Specific Effects ◽

Large Numbers ◽

Low Concentrations

The architecture of a root system plays a major role in determining how efficiently a plant can capture water and nutrients from the soil. Growth occurs at the root tips and the process of exploring the soil volume depends on the behaviour of large numbers of individual root tips at different orders of branching. Each root tip is equipped with a battery of sensory mechanisms that enable it to respond to a range of environmental signals, including nutrients, water potential, light, gravity and touch. We have previously identified a MADS (MCM1, agamous, deficiens and SRF) box gene (ANR1) in Arabidopsis thaliana that is involved in modulating the rate of lateral root growth in response to changes in the external NO3− supply. Transgenic plants have been generated in which a constitutively expressed ANR1 protein can be post-translationally activated by treatment with dexamethasone (DEX). When roots of these lines are treated with DEX, lateral root growth is markedly stimulated but there is no effect on primary root growth, suggesting that one or more components of the regulatory pathway that operate in conjunction with ANR1 in lateral roots may be absent in the primary root tip. We have recently observed some very specific effects of low concentrations of glutamate on root growth, resulting in significant changes in root architecture. Experimental evidence suggests that this response involves the sensing of extracellular glutamate by root tip cells. We are currently investigating the possible role of plant ionotropic glutamate receptors in this sensory mechanism.

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Characterization of fatty acid desaturases reveals stress-induced synthesis of C18 unsaturated fatty acids enriched in triacylglycerol in the oleaginous alga Chromochloris zofingiensis

Biotechnology for Biofuels ◽

10.1186/s13068-021-02037-2 ◽

2021 ◽

Vol 14 (1) ◽

Author(s):

Tao Wu ◽

Lihua Yu ◽

Yu Zhang ◽

Jin Liu

Keyword(s):

Mass Spectrometry ◽

Fatty Acids ◽

Unsaturated Fatty Acids ◽

De Novo ◽

Membrane Lipids ◽

Membrane Lipid ◽

Gas Chromatography Mass Spectrometry ◽

Transcription Start Sites ◽

Chromatography Mass Spectrometry ◽

Chromochloris Zofingiensis

Abstract Background The green microalga Chromochloris zofingiensis is capable of producing high levels of triacylglycerol rich in C18 unsaturated fatty acids (UFAs). FA desaturation degree is regulated by FA desaturases (FADs). Nevertheless, it remains largely unknown regarding what FADs are involved in FA desaturations and how these FADs collaborate to contribute to the high abundance of C18 UFAs in triacylglycerol in C. zofingiensis. Results To address these issues, we firstly determined the transcription start sites of 11 putative membrane-bound FAD-coding genes (CzFADs) and updated their gene models. Functional validation of these CzFADs in yeast and cyanobacterial cells revealed that seven are bona fide FAD enzymes with distinct substrates. Combining the validated functions and predicted subcellular compartments of CzFADs and the FA profiles of C. zofingiensis, the FA desaturation pathways in this alga were reconstructed. Furthermore, a multifaceted lipidomic analysis by systematically integrating thin-layer chromatography, gas chromatography–mass spectrometry and liquid chromatography–mass spectrometry techniques was conducted, unraveling profiles of polar membrane lipids in C. zofingiensis and major desaturation steps occurring in these lipids. By correlating transcriptional patterns of CzFAD genes and changes of lipids upon abiotic stress conditions, our results highlighted collaboration of CzFADs for C18 UFA synthesis and supported that both de novo FA synthesis and membrane lipid remodeling contributed C18 UFAs to triacylglycerol for storage. Conclusions Taken together, our study for the first time elucidated the pathways of C18 FA desaturations and comprehensive profiles of polar membrane lipids in C. zofingiensis and shed light on collaboration of CzFADs for the synthesis and enrichment of C18 UFAs in triacylglycerol.

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