ROS-Scavengers, Osmoprotectants and Violaxanthin De-Epoxidation in Salt-Stressed Arabidopsis thaliana with Different Tocopherol Composition

To determine the role of α- and γ-tocopherol (TC), this study compared the response to salt stress (200 mM NaCl) in wild type (WT) Arabidopsis thaliana (L.) Heynh. And its two mutants: (1) totally TC-deficient vte1; (2) vte4 accumulating γ-TC instead of α-TC; and (3) tmt transgenic line overaccumulating α-TC. Raman spectra revealed that salt-exposed α-TC accumulating plants were more flexible in regulating chlorophyll, carotenoid and polysaccharide levels than TC deficient mutants, while the plants overaccumulating γ-TC had the lowest levels of these biocompounds. Tocopherol composition and NaCl concentration affected xanthophyll cycle by changing the rate of violaxanthin de-epoxidation and zeaxanthin formation. NaCl treated plants with altered TC composition accumulated less oligosaccharides than WT plants. α-TC deficient plants increased their oligosaccharide levels and reduced maltose amount, while excessive accumulation of α-TC corresponded with enhanced amounts of maltose. Salt-stressed TC-deficient mutants and tmt transgenic line exhibited greater proline levels than WT plants, lower chlorogenic acid levels, and lower activity of catalase and peroxidases. α-TC accumulating plants produced more methylated proline- and glycine- betaines, and showed greater activity of superoxide dismutase than γ-TC deficient plants. Under salt stress, α-TC demonstrated a stronger regulatory effect on carbon- and nitrogen-related metabolites reorganization and modulation of antioxidant patterns than γ-TC. This suggested different links of α- and γ-TCs with various metabolic pathways via various functions and metabolic loops.

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Conserved Cu-MicroRNAs in Arabidopsis thaliana Function in Copper Economy under Deficiency

Plants ◽

10.3390/plants8060141 ◽

2019 ◽

Vol 8 (6) ◽

pp. 141 ◽

Cited By ~ 2

Author(s):

Muhammad Shahbaz ◽

Marinus Pilon

Keyword(s):

Arabidopsis Thaliana ◽

Small Rnas ◽

Wild Type ◽

Microrna Target ◽

Electron Carrier ◽

Cu Deficiency ◽

Regulatory Circuits ◽

Transgenic Lines ◽

Cu Homeostasis

Copper (Cu) is a micronutrient for plants. Three small RNAs, which are up-regulated by Cu deficiency and target transcripts for Cu proteins, are among the most conserved microRNAs in plants. It was hypothesized that these Cu-microRNAs help save Cu for the most essential Cu-proteins under deficiency. Testing this hypothesis has been a challenge due to the redundancy of the Cu microRNAs and the properties of the regulatory circuits that control Cu homeostasis. In order to investigate the role of Cu-microRNAs in Cu homeostasis during vegetative growth, we used a tandem target mimicry strategy to simultaneously inhibit the function of three conserved Cu-microRNAs in Arabidopsis thaliana. When compared to wild-type, transgenic lines that express the tandem target mimicry construct showed reduced Cu-microRNA accumulation and increased accumulation of transcripts that encode Cu proteins. As a result, these mimicry lines showed impaired photosynthesis and growth compared to wild type on low Cu, which could be ascribed to a defect in accumulation of plastocyanin, a Cu-containing photosynthetic electron carrier, which is itself not a Cu-microRNA target. These data provide experimental support for a Cu economy model where the Cu-microRNAs together function to allow maturation of essential Cu proteins under impending deficiency.

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A New Genetic Locus in Sinorhizobium meliloti Is Involved in Stachydrine Utilization

Applied and Environmental Microbiology ◽

10.1128/aem.64.10.3954-3960.1998 ◽

1998 ◽

Vol 64 (10) ◽

pp. 3954-3960 ◽

Cited By ~ 42

Author(s):

Donald A. Phillips ◽

Eve S. Sande ◽

J. A. C. Vriezen ◽

Frans J. de Bruijn ◽

Daniel Le Rudulier ◽

...

Keyword(s):

Salt Stress ◽

Sinorhizobium Meliloti ◽

Root Nodules ◽

Genetic Locus ◽

Wild Type ◽

Single Strain ◽

Reading Frame ◽

Carbon And Nitrogen ◽

Promoter Probe ◽

Inducible Genes

ABSTRACT Stachydrine, a betaine released by germinating alfalfa seeds, functions as an inducer of nodulation genes, a catabolite, and an osmoprotectant in Sinorhizobium meliloti. Two stachydrine-inducible genes were found in S. meliloti1021 by mutation with a Tn5-luxAB promoter probe. Both mutant strains (S10 and S11) formed effective alfalfa root nodules, but neither grew on stachydrine as the sole carbon and nitrogen source. When grown in the absence or presence of salt stress, S10 and S11 took up [14C]stachydrine as well as wild-type cells did, but neither used stachydrine effectively as an osmoprotectant. In the absence of salt stress, both S10 and S11 took up less [14C]proline than wild-type cells did. S10 and S11 appeared to colonize alfalfa roots normally in single-strain tests, but when mixed with the wild-type strain, their rhizosphere counts were reduced more than 50% (P ≤ 0.01) relative to the wild type. These results suggest that stachydrine catabolism contributes to root colonization. DNA sequence analysis identified the mutated locus in S11 as putA, and the luxABfusion in that gene was induced by proline as well as stachydrine. DNA that restored the capacity of mutant S10 to catabolize stachydrine contained a new open reading frame, stcD. All data are consistent with the concept that stcD codes for an enzyme that produces proline by demethylation of N-methylproline, a degradation product of stachydrine.

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AtSIBP1, a Novel BTB Domain-Containing Protein, Positively Regulates Salt Signaling in Arabidopsis thaliana

Plants ◽

10.3390/plants8120573 ◽

2019 ◽

Vol 8 (12) ◽

pp. 573 ◽

Cited By ~ 1

Author(s):

Xia Wan ◽

Lu Peng ◽

Jie Xiong ◽

Xiaoyi Li ◽

Jianmei Wang ◽

...

Keyword(s):

Arabidopsis Thaliana ◽

Salt Stress ◽

Marker Genes ◽

Oxygen Species ◽

Gus Gene ◽

Wild Type ◽

Btb Domain ◽

Highly Sensitive ◽

Sessile Organisms ◽

Salt Signaling

Because they are sessile organisms, plants need rapid and finely tuned signaling pathways to adapt to adverse environments, including salt stress. In this study, we identified a gene named Arabidopsis thaliana stress-induced BTB protein 1 (AtSIBP1), which encodes a nucleus protein with a BTB domain in its C-terminal side and is induced by salt and other stresses. The expression of the β-glucuronidase (GUS) gene driven by the AtSIBP1 promoter was found to be significantly induced in the presence of NaCl. The sibp1 mutant that lost AtSIBP1 function was found to be highly sensitive to salt stress and more vulnerable to salt stress than the wild type WT, while the overexpression of AtSIBP1 transgenic plants exhibited more tolerance to salt stress. According to the DAB staining, the sibp1 mutant accumulated more reactive oxygen species (ROS) than the WT and AtSIBP1 overexpression plants after salt stress. In addition, the expression levels of stress-induced marker genes in AtSIBP1 overexpression plants were markedly higher than those in the WT and sibp1 mutant plants. Therefore, our results demonstrate that AtSIBP1 was a positive regulator in salinity responses in Arabidopsis.

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Revisiting the Role of Ethylene and N-End Rule Pathway on Chilling-Induced Dormancy Release in Arabidopsis Seeds

International Journal of Molecular Sciences ◽

10.3390/ijms19113577 ◽

2018 ◽

Vol 19 (11) ◽

pp. 3577 ◽

Cited By ~ 3

Author(s):

Xu Wang ◽

Zhazira Yesbergenova-Cuny ◽

Catherine Biniek ◽

Christophe Bailly ◽

Hayat El-Maarouf-Bouteau ◽

...

Keyword(s):

Arabidopsis Thaliana ◽

Signaling Pathway ◽

Dormancy Release ◽

Ethylene Signaling ◽

Aba Signaling ◽

Wild Type ◽

Ethylene Signaling Pathway

Dormant Arabidopsis (Arabidopsis thaliana) seeds do not germinate easily at temperatures higher than 10–15 °C. Using mutants affected in ethylene signaling (etr1, ein2 and ein4) and in the N-end-rule pathway of the proteolysis (prt6 and ate1-ate2) we have investigated the effects of cold and ethylene on dormancy alleviation. Ethylene (10–100 ppm) and 2–4 days chilling (4 °C) strongly stimulate the germination of wild type (Col-0) seeds at 25 °C. Two to four days of chilling promote the germination at 25 °C of all the mutants suggesting that release of dormancy by cold did not require ethylene and did not require the N-end-rule pathway. One mutant (etr1) that did not respond to ethylene did not respond to GA3 either. Mutants affected in the N-end rule (prt6 and ate1-ate2) did not respond to ethylene indicating that also this pathway is required for dormancy alleviation by ethylene; they germinated after chilling and in the presence of GA3. Cold can activate the ethylene signaling pathway since it induced an accumulation of ETR1, EINI4, and EIN2 transcripts, the expression of which was not affected by ethylene and GA3. Both cold followed by 10 h at 25 °C and ethylene downregulated the expression of PRT6, ATE1, ATE2, and of ABI5 involved in ABA signaling as compared to dormant seeds incubated at 25 °C. In opposite, the expression of RGA, GAI, and RGL2 encoding three DELLAs was induced at 4 °C but downregulated in the presence of ethylene.

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Comparison of full-length and conserved segments of wheat dehydrin DHN-5 overexpressed in Arabidopsis thaliana showed different responses to abiotic and biotic stress

Functional Plant Biology ◽

10.1071/fp16134 ◽

2016 ◽

Vol 43 (11) ◽

pp. 1048 ◽

Cited By ~ 6

Author(s):

Marwa Drira ◽

Moez Hanin ◽

Khaled Masmoudi ◽

Faiçal Brini

Keyword(s):

Arabidopsis Thaliana ◽

Fungal Infections ◽

Alternaria Solani ◽

Triticum Aestivum L ◽

Full Length ◽

Plant Tolerance ◽

Wild Type ◽

Biotic And Abiotic Stresses ◽

Related Stress

Dehydrins (DHNs) are among the most common proteins accumulated in plants under water-related stress. They typically contain at least three conserved sequences designated as the Y-, S- and K-segments. The present work aims to highlight the role of the K-segments in plant tolerance to biotic and abiotic stresses. For this purpose, transgenic Arabidopsis thaliana (L.) Heyhn. lines expressing distinct wheat (Triticum aestivum L.) DHN-5 truncated constructs with or without the K-segments were generated. Our results showed that unlike the derivative lacking a K-segment, constructs containing only one or two K-segments enhanced the tolerance of A. thaliana to diverse stresses and were similar to the full-length wheat DHN-5. Moreover, compared with the wild-type and the YS form, the transgenic plants overexpressing wheat DHN-5 with K-segments maintained higher superoxide dismutase, catalase and peroxide dismutase enzymatic activity, and accumulated lower levels of H2O2 and malondialdehyde. In addition, we demonstrated that lines like A. thaliana overexpressing wheat DHN-5 showed increased resistance to fungal infections caused by Botrytis cinerea and Alternaria solani. Finally, the overexpression of the different forms of wheat DHN-5 led to the regulation of the expression of several genes involved in the jasmonic acid signalling pathway.

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The role of carbohydrates in the induction of flowering in Arabidopsis thaliana : comparison between the wild type and a starchless mutant

Planta ◽

10.1007/s004250050383 ◽

1998 ◽

Vol 206 (1) ◽

pp. 131-137 ◽

Cited By ~ 131

Author(s):

Laurent Corbesier ◽

Pierre Lejeune ◽

Georges Bernier

Keyword(s):

Arabidopsis Thaliana ◽

Wild Type ◽

Starchless Mutant

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Heat and cold stresses phenotypes of Arabidopsis thaliana calmodulin mutants: regulation of gamma-aminobutyric acid shunt pathway under temperature stress

International Journal of Plant Biology ◽

10.4081/pb.2012.e2 ◽

2012 ◽

Vol 3 (1) ◽

pp. 2 ◽

Cited By ~ 6

Author(s):

Nisreen A. AL-Quraan ◽

Robert D. Locy ◽

Narendra K. Singh

Keyword(s):

Arabidopsis Thaliana ◽

Heat Stress ◽

High Temperature ◽

Seed Germination ◽

Oxidative Damage ◽

Temperature Stress ◽

Wild Type ◽

Gaba Shunt ◽

Heat And Cold Stress

Plants have evolved mechanisms to cope with changes in surrounding temperatures. T-DNA insertions in seven calmodulin genes of Arabidopsis thaliana were used to investigate the role of specific calmodulin isoforms in tolerance of plants to low and high temperature for seed germination, susceptibility to low and high temperature induced oxidative damage, and changes in the levels of gammaaminobutyric acid (GABA) shunt metabolites in response to temperature stress. Exposure of wild type (WT) and cam mutant seeds at 4°C showed reduction in germination of cam5-4 and cam6-1 seeds. Exposure of cam seedlings to 42°C for 2 hr showed reduction in seed germination and survival of seedlings in cam5-4 and cam6-1 mutants compared to WT and other cam mutants. Oxidative damage by heat and cold stress measured as the level of malonaldehyde (MDA) was detected increased in root and shoot tissues of cam5- 4 and cam6-1. Oxidative damage by heat measured as the level of MDA was detected in root and shoot of most cam mutants with highest levels in cam5-4 and cam6-1. Level of GABA shunt metabolites in seedlings were gradually increased after 1 hr and 3 hr with maximum level after 6 hr and 12 hr treatments at 4ºC. GABA shunt metabolites in both root and shoot were generally elevated after 30 min and 1 hr treatment at 42°C, and increased substantially after 2 hr at 42°C comparing to the control (no treatment). GABA and glutamate levels were increased significantly more than alanine in root and shoot tissues of all cam mutants and wild type compared to the control. Alanine levels showed significant decreases in all cam mutants and in WT for 30 and 60 min of heat stress. Sensitivity of cam5-4 and cam6-1 to low temperatures suggests a role of the CAM5 and CAM6 genes in seed germination and protection against cold induced oxidative damage. Increases in the level of GABA shunt metabolites in response to cold treatment after initial reduction in some cam mutants suggests a role for calmodulin protein (cam) in the activation of glutamate decarboxylase (GAD) after exposure to cold, while increased metabolite levels may indicate involvement of other factors like reduction in cytoplasmic pH in cold regulation. Initial general elevation in GABA shunt metabolites after 30 min heat treatment in cam mutants suggests regulation of GABA level by cam. These data suggest that regulation by factors other than cam is likely, and that this factor may relate to the regulation of GAD by intracellular pH and/or metabolite partitioning under heat stress.

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Arabidopsis Phototropins Participate in the Regulation of Dark-Induced Leaf Senescence

International Journal of Molecular Sciences ◽

10.3390/ijms22041836 ◽

2021 ◽

Vol 22 (4) ◽

pp. 1836

Author(s):

Aleksandra Eckstein ◽

Joanna Grzyb ◽

Paweł Hermanowicz ◽

Piotr Zgłobicki ◽

Justyna Łabuz ◽

...

Keyword(s):

Arabidopsis Thaliana ◽

Dominant Role ◽

Photosynthetic Pigment ◽

Photochemical Activity ◽

Wild Type ◽

Delayed Senescence ◽

Photosynthetic Genes ◽

Cellular Components ◽

Senescence Associated Genes

Senescence is the final stage of plant development, affecting individual organs or the whole organism, and it can be induced by several environmental factors, including shading or darkness. Although inevitable, senescence is a complex and tightly regulated process, ensuring optimal remobilization of nutrients and cellular components from senescing organs. Photoreceptors such as phytochromes and cryptochromes are known to participate in the process of senescence, but the involvement of phototropins has not been studied to date. We investigated the role of these blue light photoreceptors in the senescence of individually darkened Arabidopsis thaliana leaves. We compared several physiological and molecular senescence markers in darkened leaves of wild-type plants and phototropin mutants (phot1, phot2, and phot1phot2). In general, all the symptoms of senescence (lower photochemical activity of photosystem II, photosynthetic pigment degradation, down-regulation of photosynthetic genes, and up-regulation of senescence-associated genes) were less pronounced in phot1phot2, as compared to the wild type, and some also in one of the single mutants, indicating delayed senescence. This points to different mechanisms of phototropin operation in the regulation of senescence-associated processes, either with both photoreceptors acting redundantly, or only one of them, phot1, playing a dominant role.

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Molecular Manipulation of the miR399/PHO2 Expression Module Alters the Salt Stress Response of Arabidopsis thaliana

Plants ◽

10.3390/plants10010073 ◽

2020 ◽

Vol 10 (1) ◽

pp. 73

Author(s):

Joseph L. Pegler ◽

Jackson M.J. Oultram ◽

Christopher P.L. Grof ◽

Andrew L Eamens

Keyword(s):

Arabidopsis Thaliana ◽

Salt Stress ◽

Target Gene ◽

Molecular Level ◽

Biological Processes ◽

Wild Type ◽

Salt Stress Response ◽

Molecular Modification ◽

Molecular Manipulation ◽

Expression Module

In Arabidopsis thaliana (Arabidopsis), the microRNA399 (miR399)/PHOSPHATE2 (PHO2) expression module is central to the response of Arabidopsis to phosphate (PO4) stress. In addition, miR399 has been demonstrated to also alter in abundance in response to salt stress. We therefore used a molecular modification approach to alter miR399 abundance to investigate the requirement of altered miR399 abundance in Arabidopsis in response to salt stress. The generated transformant lines, MIM399 and MIR399 plants, with reduced and elevated miR399 abundance respectively, displayed differences in their phenotypic and physiological response to those of wild-type Arabidopsis (Col-0) plants following exposure to a 7-day period of salt stress. However, at the molecular level, elevated miR399 abundance, and therefore, altered PHO2 target gene expression in salt-stressed Col-0, MIM399 and MIR399 plants, resulted in significant changes to the expression level of the two PO4 transporter genes, PHOSPHATE TRANSPORTER1;4 (PHT1;4) and PHT1;9. Elevated PHT1;4 and PHT1;9 PO4 transporter levels in salt stressed Arabidopsis would enhance PO4 translocation from the root to the shoot tissue which would supply additional levels of this precious cellular resource that could be utilized by the aerial tissues of salt stressed Arabidopsis to either maintain essential biological processes or to mount an adaptive response to salt stress.

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The better growth phenotype of DvGS1-transgenic arabidopsis thaliana is attributed to the improved efficiency of nitrogen assimilation

Archives of Biological Sciences ◽

10.2298/abs150414079z ◽

2015 ◽

Vol 67 (4) ◽

pp. 1107-1118

Author(s):

Chenguang Zhu ◽

Guimin Zhang ◽

Shilin Chen ◽

Wei Wang ◽

Yuanping Tang ◽

...

Keyword(s):

Amino Acids ◽

Arabidopsis Thaliana ◽

Enzymatic Activity ◽

Carbon Metabolism ◽

Transgenic Line ◽

Nitrogen Assimilation ◽

Transgenic Arabidopsis ◽

Wild Type ◽

Leaf Tissues ◽

Growth Phenotype

The overexpression of the algal glutamine synthetase (GS) gene DvGS1 in Arabidopsis thaliana resulted in higher plant biomass and better growth phenotype. The purpose of this study was to recognize the biological mechanism for the growth improvement of DvGS1-transgenic Arabidopsis. A series of molecular and biochemical investigations related to nitrogen and carbon metabolism in the DvGS1-transgenic line was conducted. Analysis of nitrogen use efficiency (NUE)-related gene transcription and enzymatic activity revealed that the transcriptional level and enzymatic activity of the genes encoding GS, glutamate synthase, glutamate dehydrogenase, alanine aminotransferase and aspartate aminotransferase, were significantly upregulated, especially from leaf tissues of the DvGS1-transgenic line under two nitrate conditions. The DvGS1-transgenic line showed increased total nitrogen content and decreased carbon: nitrogen ratio compared to wild-type plants. Significant reduced concentrations of free nitrate, ammonium, sucrose, glucose and starch, together with higher concentrations of total amino acids, individual amino acids (glutamate, aspartate, asparagine, methionine), soluble proteins and fructose in leaf tissues confirmed that the DvGS1-transgenic line demonstrated a higher efficiency of nitrogen assimilation, which subsequently affected carbon metabolism. These improved metabolisms of nitrogen and carbon conferred the DvGS1-transgenic Arabidopsis higher NUE, more biomass and better growth phenotype compared with the wild-type plants.

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