Opposite Root Growth Phenotypes of hy5 versus hy5 hyh Mutants Correlate with Increased Constitutive Auxin Signaling

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.

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RNA-Seq Transcriptome Analysis of Rice Primary Roots Reveals the Role of Flavonoids in Regulating the Rice Primary Root Growth

Genes ◽

10.3390/genes10030213 ◽

2019 ◽

Vol 10 (3) ◽

pp. 213

Author(s):

Yu Xu ◽

Junjie Zou ◽

Hongyan Zheng ◽

Miaoyun Xu ◽

Xuefeng Zong ◽

...

Keyword(s):

Cell Wall ◽

Root Growth ◽

Primary Root ◽

Glutathione Metabolism ◽

Auxin Signaling ◽

Antioxidant Enzyme Activities ◽

Rna Seq ◽

Root Tips ◽

Primary Roots ◽

Quercetin Treatment

Flavonoids play important roles in root development and in its tropic responses, whereas the flavonoids-mediated changes of the global transcription levels during root growth remain unclear. Here, the global transcription changes in quercetin-treated rice primary roots were analyzed. Quercetin treatment significantly induced the inhibition of root growth and the reduction of H2O2 and O2− levels. In addition, the RNA-seq analysis revealed that there are 1243 differentially expressed genes (DEGs) identified in quercetin-treated roots, including 1032 up-regulated and 211 down-regulated genes. A gene ontology (GO) enrichment analysis showed that the enriched GO terms are mainly associated with the cell wall organization, response to oxidative stress, and response to hormone stimulus. The Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment pathway analysis showed that the enriched DEGs are involved in phenylpropanoid biosynthesis, glutathione metabolism, and plant hormone signal transduction. Moreover, the quercetin treatment led to an increase of the antioxidant enzyme activities of catalase (CAT), peroxidase (POD), and superoxide dismutase (SOD) in rice roots. Also, the quercetin treatment altered the DR5:GUS expression pattern in the root tips. All of these data indicated that the flavonoids-mediated transcription changes of genes are related to the genes involved in cell wall remodeling, redox homeostasis, and auxin signaling, leading to a reduced cell division in the meristem zone and cell elongation in the elongation zone of roots.

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Static magnetic field regulates Arabidopsis root growth via auxin signaling

Scientific Reports ◽

10.1038/s41598-019-50970-y ◽

2019 ◽

Vol 9 (1) ◽

Cited By ~ 1

Author(s):

Yue Jin ◽

Wei Guo ◽

Xupeng Hu ◽

Mengmeng Liu ◽

Xiang Xu ◽

...

Keyword(s):

Magnetic Field ◽

Root Growth ◽

Static Magnetic Field ◽

Molecular Mechanisms ◽

Biological Significance ◽

Auxin Signaling ◽

Biological Processes ◽

Root Tips ◽

The North ◽

Living Organisms

Abstract Static magnetic field (SMF) plays important roles in biological processes of many living organisms. In plants, however, biological significance of SMF and molecular mechanisms underlying SMF action remain largely unknown. To address these questions, we treated Arabidopsis young seedlings with different SMF intensities and directions. Magnetic direction from the north to south pole was adjusted in parallel (N0) with, opposite (N180) and perpendicular to the gravity vector. We discovered that root growth is significantly inhanced by 600 mT treatments except for N180, but not by any 300 mT treatments. N0 treatments lead to more active cell division of the meristem, and higher auxin content that is regulated by coordinated expression of PIN3 and AUX1 in root tips. Consistently, N0-promoted root growth disappears in pin3 and aux1 mutants. Transcriptomic and gene ontology analyses revealed that in roots 85% of the total genes significantly down-regulated by N0 compared to untreatment are enriched in plastid biological processes, such as metabolism and chloroplast development. Lastly, no difference in root length is observed between N0-treated and untreated roots of the double cryptochrome mutant cry1 cry2. Taken together, our data suggest that SMF-regulated root growth is mediated by CRY and auxin signaling pathways in Arabidopsis.

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Effects of Light Intensity on Root Development in a D-Root Growth System

Frontiers in Plant Science ◽

10.3389/fpls.2021.778382 ◽

2021 ◽

Vol 12 ◽

Author(s):

Yohanna Evelyn Miotto ◽

Cibele Tesser da Costa ◽

Remko Offringa ◽

Jürgen Kleine-Vehn ◽

Felipe dos Santos Maraschin

Keyword(s):

Light Intensity ◽

Root Growth ◽

Root Development ◽

Light Exposure ◽

Light Condition ◽

Light Response ◽

Shoot Elongation ◽

Growth Conditions ◽

Auxin Signaling ◽

Loss Of Function

Plant development is highly affected by light quality, direction, and intensity. Under natural growth conditions, shoots are directly exposed to light whereas roots develop underground shielded from direct illumination. The photomorphogenic development strongly represses shoot elongation whereas promotes root growth. Over the years, several studies helped the elucidation of signaling elements that coordinate light perception and underlying developmental outputs. Light exposure of the shoots has diverse effects on main root growth and lateral root (LR) formation. In this study, we evaluated the phenotypic root responses of wild-type Arabidopsis plants, as well as several mutants, grown in a D-Root system. We observed that sucrose and light act synergistically to promote root growth and that sucrose alone cannot overcome the light requirement for root growth. We also have shown that roots respond to the light intensity applied to the shoot by changes in primary and LR development. Loss-of-function mutants for several root light-response genes display varying phenotypes according to the light intensity to which shoots are exposed. Low light intensity strongly impaired LR development for most genotypes. Only vid-27 and pils4 mutants showed higher LR density at 40 μmol m–2 s–1 than at 80 μmol m–2 s–1 whereas yuc3 and shy2-2 presented no LR development in any light condition, reinforcing the importance of auxin signaling in light-dependent root development. Our results support the use of D-Root systems to avoid the effects of direct root illumination that might lead to artifacts and unnatural phenotypic outputs.

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Brassinosteroid signaling delimits root gravitropism via sorting of the Arabidopsis PIN2 auxin transporter

Nature Communications ◽

10.1038/s41467-019-13543-1 ◽

2019 ◽

Vol 10 (1) ◽

Cited By ~ 10

Author(s):

Katarzyna Retzer ◽

Maria Akhmanova ◽

Nataliia Konstantinova ◽

Kateřina Malínská ◽

Johannes Leitner ◽

...

Keyword(s):

Root Growth ◽

De Novo ◽

Root Tip ◽

Auxin Signaling ◽

Membrane Domains ◽

Signaling Crosstalk ◽

Brassinosteroid Signaling ◽

Root Gravitropism ◽

Auxin Transporter ◽

De Novo Protein Synthesis

AbstractArabidopsis PIN2 protein directs transport of the phytohormone auxin from the root tip into the root elongation zone. Variation in hormone transport, which depends on a delicate interplay between PIN2 sorting to and from polar plasma membrane domains, determines root growth. By employing a constitutively degraded version of PIN2, we identify brassinolides as antagonists of PIN2 endocytosis. This response does not require de novo protein synthesis, but involves early events in canonical brassinolide signaling. Brassinolide-controlled adjustments in PIN2 sorting and intracellular distribution governs formation of a lateral PIN2 gradient in gravistimulated roots, coinciding with adjustments in auxin signaling and directional root growth. Strikingly, simulations indicate that PIN2 gradient formation is no prerequisite for root bending but rather dampens asymmetric auxin flow and signaling. Crosstalk between brassinolide signaling and endocytic PIN2 sorting, thus, appears essential for determining the rate of gravity-induced root curvature via attenuation of differential cell elongation.

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

10.1101/2021.01.05.425399 ◽

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.

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E3 ubiquitin ligase SOR1 regulates ethylene response in rice root by modulating stability of Aux/IAA protein

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1719387115 ◽

2018 ◽

Vol 115 (17) ◽

pp. 4513-4518 ◽

Cited By ~ 19

Author(s):

Hui Chen ◽

Biao Ma ◽

Yang Zhou ◽

Si-Jie He ◽

San-Yuan Tang ◽

...

Keyword(s):

Root Growth ◽

Ubiquitin Ligase ◽

Plant Root ◽

E3 Ubiquitin Ligase ◽

Ring Finger ◽

Soil Surface ◽

26S Proteasome ◽

Auxin Signaling ◽

Transcriptional Repressors ◽

Root Growth And Development

Plant hormones ethylene and auxin synergistically regulate plant root growth and development. Ubiquitin-mediated proteolysis of Aux/IAA transcriptional repressors by the E3 ubiquitin ligase SCFTIR1/AFB triggers a transcription-based auxin signaling. Here we show that rice (Oryza sativa L.) soil-surface rooting 1 (SOR1), which is a RING finger E3 ubiquitin ligase identified from analysis of a rice ethylene-insensitive mutant mhz2/sor1-2, controls root-specific ethylene responses by modulating Aux/IAA protein stability. SOR1 physically interacts with OsIAA26 and OsIAA9, which are atypical and canonical Aux/IAA proteins, respectively. SOR1 targets OsIAA26 for ubiquitin/26S proteasome-mediated degradation, whereas OsIAA9 protects the OsIAA26 protein from degradation by inhibiting the E3 activity of SOR1. Auxin promotes SOR1-dependent degradation of OsIAA26 by facilitating SCFOsTIR1/AFB2-mediated and SOR1-assisted destabilization of OsIAA9 protein. Our study provides a candidate mechanism by which the SOR1-OsIAA26 module acts downstream of the OsTIR1/AFB2-auxin-OsIAA9 signaling to modulate ethylene inhibition of root growth in rice seedlings.

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Arabidopsis HB52 mediates the crosstalk between ethylene and auxin signaling pathways by regulating PIN2, WAG1, and WAG2 during primary root elongation

10.1101/246017 ◽

2018 ◽

Author(s):

Zi-Qing Miao ◽

Ping-Xia Zhao ◽

Jie-Li Mao ◽

Lin-Hui Yu ◽

Yang Yuan ◽

...

Keyword(s):

Root Growth ◽

Signaling Pathways ◽

Molecular Mechanism ◽

Root Elongation ◽

Auxin Transport ◽

Primary Root ◽

Auxin Signaling ◽

Elongation Zone ◽

Ethylene Signaling ◽

Physiological Processes

AbstractThe gaseous hormone ethylene participates in many physiological processes of plants. It is well known that ethylene-inhibited root elongation involves basipetal auxin delivery requiring PIN2. However, the molecular mechanism how ethylene regulates PIN2 is not well understood. Here, we report that the ethylene-responsive HD-Zip gene HB52 is involved in ethylene-mediated inhibition of primary root elongation. Using biochemical and genetic analyses, we demonstrated that HB52 is ethylene-responsive and acts immediately downstream of EIN3. HB52 knock-down mutants are insensitive to ethylene in primary root elongation while the overexpression lines have dramatically shortened roots like ethylene treated plants. Moreover, HB52 upregulates PIN2, WAG1, and WAG2 by directly binding to their promoter, leading to an enhanced basipetal auxin delivery to the elongation zone and thus inhibiting root growth. Our work uncovers HB52 as an important crosstalk node between ethylene signaling and auxin transport in root elongation.

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Mitogen-Activated Protein Kinase 6 and Ethylene and Auxin Signaling Pathways Are Involved in Arabidopsis Root-System Architecture Alterations by Trichoderma atroviride

Molecular Plant-Microbe Interactions ◽

10.1094/mpmi-01-15-0005-r ◽

2015 ◽

Vol 28 (6) ◽

pp. 701-710 ◽

Cited By ~ 52

Author(s):

Hexon Angel Contreras-Cornejo ◽

Jesús Salvador López-Bucio ◽

Alejandro Méndez-Bravo ◽

Lourdes Macías-Rodríguez ◽

Maricela Ramos-Vega ◽

...

Keyword(s):

Protein Kinase ◽

Root Growth ◽

System Architecture ◽

Primary Root ◽

Root System Architecture ◽

Mitogen Activated Protein Kinase ◽

Auxin Signaling ◽

Trichoderma Atroviride ◽

Mitogen Activated Protein ◽

Primary Root Growth

Trichoderma atroviride is a symbiotic fungus that interacts with roots and stimulates plant growth and defense. Here, we show that Arabidopsis seedlings cocultivated with T. atroviride have an altered root architecture and greater biomass compared with axenically grown seedlings. These effects correlate with increased activity of mitogen-activated protein kinase 6 (MPK6). The primary roots of mpk6 mutants showed an enhanced growth inhibition by T. atroviride when compared with wild-type (WT) plants, while T. atroviride increases MPK6 activity in WT roots. It was also found that T. atroviride produces ethylene (ET), which increases with l-methionine supply to the fungal growth medium. Analysis of growth and development of WT seedlings and etr1, ein2, and ein3 ET-related Arabidopsis mutants indicates a role for ET in root responses to the fungus, since etr1 and ein2 mutants show defective root-hair induction and enhanced primary-root growth inhibition when cocultivated with T. atroviride. Increased MPK6 activity was evidenced in roots of ctr1 mutants, which correlated with repression of primary root growth, thus connecting MPK6 signaling with an ET response pathway. Auxin-inducible gene expression analysis using the DR5:uidA reporter construct further revealed that ET affects auxin signaling through the central regulator CTR1 and that fungal-derived compounds, such as indole-3-acetic acid and indole-3-acetaldehyde, induce MPK6 activity. Our results suggest that T. atroviride likely alters root-system architecture modulating MPK6 activity and ET and auxin action.

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