Auxin-modulated root growth inhibition in Arabidopsis thaliana seedlings with ammonium as the sole nitrogen source

2015 ◽  
Vol 42 (3) ◽  
pp. 239 ◽  
Author(s):  
Huaiyu Yang ◽  
Jenny von der Fecht-Bartenbach ◽  
Jiřř Friml ◽  
Jan U. Lohmann ◽  
Benjamin Neuhäuser ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Root Growth ◽  
Nitrogen Source ◽  
Seedling Survival ◽  
Root Growth Inhibition ◽  
Gus Reporter ◽  
Primary Roots ◽  
Hormone Responses ◽  
Ammonium Stress ◽  
High Concentrations

Ammonium is the major nitrogen source in some plant ecosystems but is toxic at high concentrations, especially when available as the exclusive nitrogen source. Ammonium stress rapidly leads to various metabolic and hormonal imbalances that ultimately inhibit root and shoot growth in many plant species, including Arabidopsis thaliana (L.) Heynh. To identify molecular and genetic factors involved in seedling survival with prolonged exclusive NH4+ nutrition, a transcriptomic analysis with microarrays was used. Substantial transcriptional differences were most pronounced in (NH4)2SO4-grown seedlings, compared with plants grown on KNO3 or NH4NO3. Consistent with previous physiological analyses, major differences in the expression modules of photosynthesis-related genes, an altered mitochondrial metabolism, differential expression of the primary NH4+ assimilation, alteration of transporter gene expression and crucial changes in cell wall biosynthesis were found. A major difference in plant hormone responses, particularly of auxin but not cytokinin, was striking. The activity of the DR5::GUS reporter revealed a dramatically decreased auxin response in (NH4)2SO4-grown primary roots. The impaired root growth on (NH4)2SO4 was partially rescued by exogenous auxin or in specific mutants in the auxin pathway. The data suggest that NH4+-induced nutritional and metabolic imbalances can be partially overcome by elevated auxin levels.

Melatonin alleviates aluminium toxicity through modulating antioxidative enzymes and enhancing organic acid anion exudation in soybean

2017 ◽  
Vol 44 (10) ◽  
pp. 961 ◽  
Author(s):  
Jiarong Zhang ◽  
Bingjie Zeng ◽  
Yawen Mao ◽  
Xiangying Kong ◽  
Xinxun Wang ◽  
...  
Keyword(s):  
Plant Growth ◽  
Root Growth ◽  
Critical Role ◽  
Aluminium Toxicity ◽  
Al Toxicity ◽  
Root Growth Inhibition ◽  
H2o2 Production ◽  
Plant Responses ◽  
Al Stress ◽  
High Concentrations

Aluminium (Al) toxicity is a major chemical constraint limiting plant growth and production on acidic soils. Melatonin (N-acetyl-5-methoxytryptamine) is a ubiquitous molecule that plays crucial roles in plant growth and stress tolerance. However, there is no knowledge regarding whether melatonin is involved in plant responses to Al stress. Here, we show that optimal concentrations of melatonin could effectively ameliorate Al-induced phytotoxicity in soybean (Glycine max L.). The concentration of melatonin in roots was significantly increased by the 50 μM Al treatment. Such an increase in endogenous melatonin coincided with the upregulation of the gene encoding acetyltransferase NSI-like (nuclear shuttle protein-interacting) in soybean roots. Supplementation with low concentrations of melatonin (0.1 and 1 μM) conferred Al resistance as evident in partial alleviation of root growth inhibition and decreased H2O2 production: in contrast, high concentrations of melatonin (100 and 200 μM) had an opposite effect and even decreased root growth in Al-exposed seedlings. Mitigation of Al stress by the 1 μM melatonin root treatment was associated with enhanced activities of the antioxidant enzymes and increased exudation of malate and citrate. In conclusion, melatonin might play a critical role in soybean resistance to Al toxicity.

scholarly journals The AFB1 auxin receptor controls rapid auxin signaling and root growth through membrane depolarization in Arabidopsis thaliana

2021 ◽  
Author(s):  
Nelson BC Serre ◽  
Dominik Kralík ◽  
Ping Yun ◽  
Sergey Shabala ◽  
Zdeněk Slouka ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Root Growth ◽  
Growth Inhibition ◽  
Cell Types ◽  
Membrane Depolarization ◽  
Root Growth Inhibition ◽  
Auxin Signaling ◽  
Auxin Receptor ◽  
Transcriptional Responses

AbstractThe existence of an electric gradient across membranes is essential for a cell operation. In plants, application of the growth regulator auxin (IAA) causes almost instantaneous membrane depolarization in various cell types, making membrane depolarization a hallmark of the rapid non-transcriptional responses to IAA. Auxin triggers rapid root growth inhibition; a process that underlies gravitropic bending. The growth and depolarization responses to auxin show remarkable similarities in dynamics, requirement of auxin influx and the involvement of the TIR1/AFB auxin coreceptors, but whether auxin-induced depolarization participates in root growth inhibition remains unanswered. Here, we established a toolbox to dynamically visualize membrane potential in vivo in Arabidopsis thaliana roots by combining the DISBAC2(3) fluorescent probe with microfluidics and vertical stage microscopy. This way we show that auxin-induced membrane depolarization tightly correlates with rapid root growth inhibition and that the cells of the transition zone/early elongation zone are the most responsive to auxin. Further, we demonstrate that auxin cycling in and out of the cells through AUX1 influx and PIN2 efflux is not essential for membrane depolarization and rapid root growth inhibition but acts as a facilitator of these responses. The rapid membrane depolarization by auxin instead strictly depends on the AFB1 auxin receptor, while the other TIR1/AFB paralogues contribute to this response. The lack of membrane depolarization in the afb1 mutant explains the lack of the immediate root growth inhibition. Finally, we show that AFB1 is required for the rapid depolarization and rapid growth inhibition of cells at the lower side of the gravistimulated root. These results are instrumental in understanding the physiological significance of membrane depolarization for the gravitropic response of the root and clarify the role of AFB1 as the receptor central for rapid auxin responses, adding another piece to the puzzle in understanding the biology of the phytohormone auxin.

scholarly journals Jasmonate Signalling Contributes to Primary Root Inhibition Upon Oxygen Deficiency in Arabidopsis thaliana

Plants ◽  
2020 ◽  
Vol 9 (8) ◽  
pp. 1046 ◽  
Author(s):  
Vinay Shukla ◽  
Lara Lombardi ◽  
Ales Pencik ◽  
Ondrej Novak ◽  
Daan A. Weits ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Root Growth ◽  
Growth Inhibition ◽  
Feedback Inhibition ◽  
Oxygen Sensing ◽  
Oxygen Deficiency ◽  
Primary Root ◽  
Root Growth Inhibition ◽  
Root Inhibition ◽  
Active Root

Plants, including most crops, are intolerant to waterlogging, a stressful condition that limits the oxygen available for roots, thereby inhibiting their growth and functionality. Whether root growth inhibition represents a preventive measure to save energy or is rather a consequence of reduced metabolic rates has yet to be elucidated. In the present study, we gathered evidence for hypoxic repression of root meristem regulators that leads to root growth inhibition. We also explored the contribution of the hormone jasmonic acid (JA) to this process in Arabidopsis thaliana. Analysis of transcriptomic profiles, visualisation of fluorescent reporters and direct hormone quantification confirmed the activation of JA signalling under hypoxia in the roots. Further, root growth assessment in JA-related mutants in aerobic and anaerobic conditions indicated that JA signalling components contribute to active root inhibition under hypoxia. Finally, we show that the oxygen-sensing transcription factor (TF) RAP2.12 can directly induce Jasmonate Zinc-finger proteins (JAZs), repressors of JA signalling, to establish feedback inhibition. In summary, our study sheds new light on active root growth restriction under hypoxic conditions and on the involvement of the JA hormone in this process and its cross talk with the oxygen sensing machinery of higher plants.

scholarly journals Sound Waves Promote Arabidopsis thaliana Root Growth by Regulating Root Phytohormone Content

2021 ◽  
Vol 22 (11) ◽  
pp. 5739
Author(s):  
Joo Yeol Kim ◽  
Hyo-Jun Lee ◽  
Jin A Kim ◽  
Mi-Jeong Jeong
Keyword(s):  
Arabidopsis Thaliana ◽  
Cell Division ◽  
Root Growth ◽  
Apical Meristem ◽  
Cell Number ◽  
Root Apical Meristem ◽  
Control Group ◽  
Auxin Signaling ◽  
Ethylene Signaling ◽  
Sound Waves

Sound waves affect plants at the biochemical, physical, and genetic levels. However, the mechanisms by which plants respond to sound waves are largely unknown. Therefore, the aim of this study was to examine the effect of sound waves on Arabidopsis thaliana growth. The results of the study showed that Arabidopsis seeds exposed to sound waves (100 and 100 + 9k Hz) for 15 h per day for 3 day had significantly longer root growth than that in the control group. The root length and cell number in the root apical meristem were significantly affected by sound waves. Furthermore, genes involved in cell division were upregulated in seedlings exposed to sound waves. Root development was affected by the concentration and activity of some phytohormones, including cytokinin and auxin. Analysis of the expression levels of genes regulating cytokinin and auxin biosynthesis and signaling showed that cytokinin and ethylene signaling genes were downregulated, while auxin signaling and biosynthesis genes were upregulated in Arabidopsis exposed to sound waves. Additionally, the cytokinin and auxin concentrations of the roots of Arabidopsis plants increased and decreased, respectively, after exposure to sound waves. Our findings suggest that sound waves are potential agricultural tools for improving crop growth performance.

PLC1 and H2O2 Mediated the Allelopathic Effect of Oridonin on Root Growth in Arabidopsis thaliana

2021 ◽  
Author(s):  
Yue Zhang ◽  
Yanhuang An ◽  
Ning Yang ◽  
Wei Wang ◽  
Ruirui Liu ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Root Growth ◽  
Allelopathic Effect

Foliar vs. Root Sensitivity of Hairy Bittercress (Cardamine hirsuta) to Isoxaben

2006 ◽  
Vol 20 (2) ◽  
pp. 326-333 ◽  
Author(s):  
Glenn Wehtje ◽  
Charles H. Gilliam ◽  
Michael E. Miller ◽  
James E. Altland
Keyword(s):  
Root Growth ◽  
Environmental Conditions ◽  
Day Length ◽  
Root Growth Inhibition ◽  
Root Absorption ◽  
Nursery Production ◽  
Plant Maturity ◽  
Higher Temperature ◽  
Inhibit Root Growth ◽  
Hydroponically Grown

It has been previously reported that POST-applied isoxaben can effectively control established hairy bittercress. Experiments were conducted to determine the relative importance of root vs. foliar entry of POST-applied isoxaben. At a common isoxaben rate of 0.56 kg/ha, foliar-only and foliar plus soil applications provided 10.5 and 23.3% control, respectively, as determined by fresh weight reduction. In contrast, soil-only application provided 47.0% control. Hairy bittercress foliar absorption of14C–isoxaben did not exceed 15% of the amount applied after 72 h. Therefore, the comparatively less effectiveness of foliar-only applications may be attributed primarily to limited absorption. Minimal isoxaben concentration required to inhibit root growth of hydroponically grown hairy bittercress was 0.0025 mg/L. Higher concentrations were required to produce a response in the foliage. Sorption of isoxaben by pine bark rooting substrate, typical of what is used in container nursery production, exceeded 99% of amount applied after 36 h. Even with 99% sorption, the probable concentration within the aqueous phase remains sufficient to inhibit hairy bittercress root growth. Additional studies with14C–isoxaben established that approximately 35% of the root-absorbed isoxaben was translocated into the foliage. Translocation from the roots into the foliage was reduced to 16% when the experiment was repeated during environmental conditions less favorable for vegetative growth (i.e., longer day length and higher temperature). Results indicate that the control of hairy bittercress with POST-applied isoxaben is likely the result of root absorption and root-growth inhibition. Expression of phytotoxicity within the foliage is also a component, but is dependent upon the root-absorbed isoxaben being translocated into the foliage. Extent of this translocation is dependent upon plant maturity and prevalent environmental conditions.

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