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

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

International Journal of Molecular Sciences ◽

10.3390/ijms222111370 ◽

2021 ◽

Vol 22 (21) ◽

pp. 11370

Author(s):

Ewa Surówka ◽

Dariusz Latowski ◽

Michał Dziurka ◽

Magdalena Rys ◽

Anna Maksymowicz ◽

...

Keyword(s):

Arabidopsis Thaliana ◽

Salt Stress ◽

Transgenic Line ◽

Wild Type ◽

Carbon And Nitrogen ◽

Nacl Concentration ◽

Tocopherol Composition ◽

Ros Scavengers ◽

Excessive Accumulation

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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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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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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PAD4-Dependent Antibiosis Contributes to the ssi2-Conferred Hyper-Resistance to the Green Peach Aphid

Molecular Plant-Microbe Interactions ◽

10.1094/mpmi-23-5-0618 ◽

2010 ◽

Vol 23 (5) ◽

pp. 618-627 ◽

Cited By ~ 25

Author(s):

Joe Louis ◽

Queena Leung ◽

Venkatramana Pegadaraju ◽

John Reese ◽

Jyoti Shah

Keyword(s):

Arabidopsis Thaliana ◽

Salicylic Acid ◽

Green Peach Aphid ◽

Insect Behavior ◽

Antibiotic Activity ◽

Broad Host Range ◽

Wild Type ◽

Elevated Expression ◽

Insect Reproduction

Myzus persicae, commonly known as green peach aphid (GPA), is a sap-sucking insect with a broad host range. Arabidopsis thaliana responds to GPA infestation with elevated expression of the PHYTOALEXIN DEFICIENT4 (PAD4) gene. Previously, we had demonstrated that the loss of PAD4 gene function compromises Arabidopsis resistance to GPA. In contrast, a mutation in the Arabidopsis SUPPRESSOR OF SALICYLIC ACID INSENSITIVITY2 (SSI2) gene, which encodes a desaturase involved in lipid metabolism, resulted in hyper-resistance to GPA. We demonstrate here that PAD4 is required for the ssi2-dependent heightened resistance to GPA. Based on electrical monitoring of insect behavior and bioassays in which the insect was given a choice between the wild type and the ssi2 mutant, it is concluded that the ssi2-conferred resistance is not due to deterrence of insect settling or feeding from the phloem of the mutant. Instead, hyper-resistance in the ssi2 mutant results from heightened antibiosis that curtails insect reproduction. Petiole exudates collected from uninfested ssi2 plants contain elevated levels of an activity that interferes with aphid reproduction in synthetic diets. PAD4 was required for the accumulation of this antibiotic activity in petiole exudates, supporting the role of PAD4 in phloem-based resistance. Because PAD4 expression is not elevated in the ssi2 mutant, we suggest that basal PAD4 expression contributes to this antibiosis.

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The role of SORBITOL DEHYDROGENASE in Arabidopsis thaliana

Functional Plant Biology ◽

10.1071/fp12008 ◽

2012 ◽

Vol 39 (6) ◽

pp. 462 ◽

Cited By ~ 18

Author(s):

Marta Nosarzewski ◽

A. Bruce Downie ◽

Benhong Wu ◽

Douglas D. Archbold

Keyword(s):

Arabidopsis Thaliana ◽

Drought Stress ◽

Sorbitol Dehydrogenase ◽

Primary Role ◽

Dependent Manner ◽

Plant Leaves ◽

Wild Type ◽

Concentration Dependent Manner ◽

Knockout Mutants

SORBITOL DEHYDROGENASE (SDH, EC 1.1.1.14) catalyses the interconversion of polyols and ketoses (e.g. sorbitol ↔ fructose). Using two independent Arabidopsis thaliana (L.) Heynh. sdh knockout mutants, we show that SDH (At5g51970) plays a primary role in sorbitol metabolism as well as an unexpected role in ribitol metabolism. Sorbitol content increased in both wild-type (WT) and mutant plant leaves during drought stress, but mutants showed a dramatically different phenotype, dying even if rewatered. The lack of functional SDH in mutant plants was accompanied by accumulation of foliar sorbitol and at least 10-fold more ribitol, neither of which decreased in mutant plants after rewatering. In addition, mutant plants were uniquely sensitive to ribitol in a concentration-dependent manner, which either prevented them from completing seed germination or inhibited seedling development, effects not observed with other polyols or with ribitol-treated WT plants. Ribitol catabolism may occur solely through SDH in A. thaliana, though at only 30% the rate of that for sorbitol. The results indicate a role for SDH in metabolism of sorbitol to fructose and in ribitol conversion to ribulose in A. thaliana during recovery from drought stress.

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