scholarly journals The BEACH Domain-Containing Protein SPIRRIG Modulates Actin-Dependent Root Hair Development in Coordination with the WAVE/SCAR and ARP2/3 Complexes

2020 ◽  
Author(s):  
Sabrina Chin ◽  
Taegun Kwon ◽  
Bibi Rafeiza Khan ◽  
J. Alan Sparks ◽  
Eileen L. Mallery ◽  
...  
Keyword(s):  
Membrane Trafficking ◽  
Root Hair ◽  
Tip Growth ◽  
Developmental Stages ◽  
Root Hairs ◽  
Filamentous Actin ◽  
Root Hair Development ◽  
Live Cell Microscopy ◽  
Hair Development ◽  
Cellular Components

AbstractRoot hairs are single cell protrusions that enable roots to optimize nutrient and water acquisition. They attain their tubular shapes by confining growth to the cell apex, a process called tip growth. The actin cytoskeleton and endomembrane system are essential for tip growth; however, little is known about how these cellular components coordinate their activities during this process. Here, we show that SPIRRIG (SPI), a BEACH domain-containing protein involved in membrane trafficking, and BRK1 and SCAR2, subunits of the WAVE/SCAR (W/SCR) and actin related protein (ARP)2/3 activation complexes, display polarized localizations to root hairs at distinct developmental stages. SPI accumulates at the root hair apex via post-Golgi vesicles and positively regulates tip growth by maintaining tip-focused vesicle secretion and filamentous-actin integrity. BRK1 and SCAR2 on the other hand, mark the root hair initiation domain to specify the position of root hair emergence. Live cell microscopy revealed that BRK1 depletion coincided with SPI accumulation as root hairs transitioned from initiation to tip growth. Furthermore, double mutant studies showed that SPI genetically interacts with BRK1 and ARP2/3. Taken together, our work uncovers a role for SPI in facilitating actin-dependent root hair development through pathways that intersect with the W/SCR and ARP2/3 complexes.

Spatial and temporal localization of SPIRRIG and WAVE/SCAR reveal roles for these proteins in actin-mediated root hair development

2021 ◽  
Author(s):  
Sabrina Chin ◽  
Taegun Kwon ◽  
Bibi Rafeiza Khan ◽  
J Alan Sparks ◽  
Eileen L Mallery ◽  
...  
Keyword(s):  
Membrane Trafficking ◽  
Root Hair ◽  
Tip Growth ◽  
Developmental Stages ◽  
Root Hairs ◽  
Filamentous Actin ◽  
Root Hair Development ◽  
Hair Development ◽  
Temporal Localization ◽  
Cellular Components

Abstract Root hairs are single cell protrusions that enable roots to optimize nutrient and water acquisition. These structures attain their tubular shapes by confining growth to the cell apex, a process called tip growth. The actin cytoskeleton and endomembrane systems are essential for tip growth; however, little is known about how these cellular components coordinate their activities during this process. Here, we show that SPIRRIG (SPI), a BEACH domain-containing protein involved in membrane trafficking, and BRK1 and SCAR2, subunits of the WAVE/SCAR (W/SC) actin nucleating promoting complex, display polarized localizations in Arabidopsis thaliana root hairs during distinct developmental stages. SPI accumulates at the root hair apex via post-Golgi compartments and positively regulates tip growth by maintaining tip-focused vesicle secretion and filamentous-actin integrity. BRK1 and SCAR2 on the other hand, mark the root hair initiation domain to specify the position of root hair emergence. Consistent with the localization data, tip growth was reduced in spi and the position of root hair emergence was disrupted in brk1 and scar1234. BRK1 depletion coincided with SPI accumulation as root hairs transitioned from initiation to tip growth. Taken together, our work uncovers a role for SPI in facilitating actin-dependent root hair development in Arabidopsis through pathways that might intersect with W/SC.

scholarly journals Root hair specification and its growth in response to nutrients

2021 ◽  
Vol 49 (2) ◽  
pp. 12258
Author(s):  
Xian HUANG ◽  
Tianzhi GONG ◽  
Mei LI ◽  
Cenghong HU ◽  
Dejian ZHANG ◽  
...  
Keyword(s):  
Root Hair ◽  
Reverse Genetics ◽  
Current Knowledge ◽  
Plant Root ◽  
Root Hairs ◽  
Root Surface ◽  
Root Surface Area ◽  
Root Hair Development ◽  
Hair Development ◽  
Calcium Iron

Plant root hairs are cylindrical tubular projections from root epidermal cells. They increase the root surface area, which is important for the acquisition of water and nutrients, microbe interactions, and plant anchorage. The root hair specification, the effect of root hairs on nutrient acquisition and the mechanisms of nutrients (calcium, iron, magnesium, nitrogen, phosphorus, and potassium) that affect root hair development and growth were reviewed. The gene regulatory network on root hair specification in the plant kingdom was highlighted. More work is needed to clone the genes of additional root hair mutants and elucidate their roles, as well as undertaking reverse genetics and mutant complementation studies to add to the current knowledge of the signaling networks, which are involved in root hair development and growth regulated by nutrients.

scholarly journals Functional Characterization of fer-ts, a Temperature-Sensitive FERONIA Mutant Allele That Alters Root Hair Growth

2020 ◽  
Author(s):  
Daewon Kim ◽  
Jiyuan Yang ◽  
Fangwei Gu ◽  
Sung Jin Park ◽  
Jonathon Combs ◽  
...  
Keyword(s):  
Root Hair ◽  
Plasma Membranes ◽  
Tip Growth ◽  
Elevated Temperatures ◽  
Functional Characterization ◽  
Root Hairs ◽  
Temperature Sensitive ◽  
Genetic Screens ◽  
Binding Domains ◽  
Cellular Components

ABSTRACTIn plants, root hairs undergo a highly-polarized form of cell expansion called tip-growth, in which cell wall deposition is restricted to the root hair apex. In order to identify essential cellular components that might have been missed in earlier genetic screens we identified conditional temperature sensitive (ts) root hair mutants by EMS mutagenesis. Here we describe one of these mutants, fer-ts (feronia-temperature sensitive). Mutant fer-ts seedlings grew normally at normal temperatures (20°C), but failed to form root hairs at elevated temperatures (30°C). Map based-cloning and whole genome sequencing revealed that fer-ts resulted from a G41S substitution in the extracellular domain of FERONIA (FER). A functional fluorescent fusion of FER containing the fer-ts mutation localized to plasma membranes, but was subject to enhanced protein turnover at elevated temperatures. While tip-growth was rapidly inhibited by addition of RALF1 peptides in both wild-type and fer-ts mutants at normal temperatures, root elongation of fer-ts seedlings was resistant to added RALF1 peptide at elevated temperatures. Additionally, at elevated temperatures fer-ts seedlings displayed altered ROS accumulation upon auxin treatment and phenocopied constitutive fer mutant responses to a variety of plant hormone treatments. Molecular modeling and sequence comparison with other CrRLK1L receptor family members revealed that the mutated glycine in fer-ts is highly conserved, but is not located in the recently characterized RALF23 and LORELI-LIKE-GLYCOPROTEIN (LLG2) binding domains, perhaps suggesting that fer-ts phenotypes may not be directly due to loss of binding to RALF1 peptides.

scholarly journals ACTIN2 Is Essential for Bulge Site Selection and Tip Growth during Root Hair Development of Arabidopsis

2002 ◽  
Vol 129 (4) ◽  
pp. 1464-1472 ◽  
Author(s):  
Christoph Ringli ◽  
Nicolas Baumberger ◽  
Anouck Diet ◽  
Beat Frey ◽  
Beat Keller
Keyword(s):  
Root Hair ◽  
Site Selection ◽  
Tip Growth ◽  
Root Hair Development ◽  
Hair Development

scholarly journals Root hairs are the most important root trait for rhizosheath formation of barley (Hordeum vulgare), maize (Zea mays) and Lotus japonicus (Gifu)

2021 ◽  
Author(s):  
Emma Burak ◽  
John N Quinton ◽  
Ian C Dodd
Keyword(s):  
Zea Mays ◽  
Hordeum Vulgare ◽  
Root Hair ◽  
Root Length ◽  
Root Exudate ◽  
Lotus Japonicus ◽  
Root Hairs ◽  
Root Hair Development ◽  
Maize Genotypes ◽  
Hair Development

Abstract Background and Aims Rhizosheaths are defined as the soil adhering to the root system after it is extracted from the ground. Root hairs and mucilage (root exudates) are key root traits involved in rhizosheath formation, but to better understand the mechanisms involved their relative contributions should be distinguished. Methods The ability of three species [barley (Hordeum vulgare), maize (Zea mays) and Lotus japonicus (Gifu)] to form a rhizosheath in a sandy loam soil was compared with that of their root-hairless mutants [bald root barley (brb), maize root hairless 3 (rth3) and root hairless 1 (Ljrhl1)]. Root hair traits (length and density) of wild-type (WT) barley and maize were compared along with exudate adhesiveness of both barley and maize genotypes. Furthermore, root hair traits and exudate adhesiveness from different root types (axile versus lateral) were compared within the cereal species. Key Results Per unit root length, rhizosheath size diminished in the order of barley > L. japonicus > maize in WT plants. Root hairs significantly increased rhizosheath formation of all species (3.9-, 3.2- and 1.8-fold for barley, L. japonicus and maize, respectively) but there was no consistent genotypic effect on exudate adhesiveness in the cereals. While brb exudates were more and rth3 exudates were less adhesive than their respective WTs, maize rth3 bound more soil than barley brb. Although both maize genotypes produced significantly more adhesive exudate than the barley genotypes, root hair development of WT barley was more extensive than that of WT maize. Thus, the greater density of longer root hairs in WT barley bound more soil than WT maize. Root type did not seem to affect rhizosheath formation, unless these types differed in root length. Conclusions When root hairs were present, greater root hair development better facilitated rhizosheath formation than root exudate adhesiveness. However, when root hairs were absent root exudate adhesiveness was a more dominant trait.

EIN3 and RSL4 interfere with an MYB–bHLH–WD40 complex to mediate ethylene-induced ectopic root hair formation in Arabidopsis

2021 ◽  
Vol 118 (51) ◽  
pp. e2110004118
Author(s):  
Yuping Qiu ◽  
Ran Tao ◽  
Ying Feng ◽  
Zhina Xiao ◽  
Dan Zhang ◽  
...  
Keyword(s):  
Root Hair ◽  
Molecular Mechanisms ◽  
Protein Complexes ◽  
Root Hairs ◽  
Elongation Factor ◽  
Root Hair Development ◽  
Root Hair Formation ◽  
Hair Development ◽  
Transcriptional Complex ◽  
Hair Formation

The alternating cell specifications of root epidermis to form hair cells or nonhair cells in Arabidopsis are determined by the expression level of GL2, which is activated by an MYB–bHLH–WD40 (WER–GL3–TTG1) transcriptional complex. The phytohormone ethylene (ET) has a unique effect of inducing N-position epidermal cells to form root hairs. However, the molecular mechanisms underlying ET-induced ectopic root hair development remain enigmatic. Here, we show that ET promotes ectopic root hair formation through down-regulation of GL2 expression. ET-activated transcription factors EIN3 and its homolog EIL1 mediate this regulation. Molecular and biochemical analyses further revealed that EIN3 physically interacts with TTG1 and interferes with the interaction between TTG1 and GL3, resulting in reduced activation of GL2 by the WER–GL3–TTG1 complex. Furthermore, we found through genetic analysis that the master regulator of root hair elongation, RSL4, which is directly activated by EIN3, also participates in ET-induced ectopic root hair development. RSL4 negatively regulates the expression of GL2, likely through a mechanism similar to that of EIN3. Therefore, our work reveals that EIN3 may inhibit gene expression by affecting the formation of transcription-activating protein complexes and suggests an unexpected mutual inhibition between the hair elongation factor, RSL4, and the hair specification factor, GL2. Overall, this study provides a molecular framework for the integration of ET signaling and intrinsic root hair development pathway in modulating root epidermal cell specification.

scholarly journals The karrikin signaling regulator SMAX1 controlsLotus japonicusroot and root hair development by suppressing ethylene biosynthesis

2020 ◽  
Vol 117 (35) ◽  
pp. 21757-21765 ◽  
Author(s):  
Samy Carbonnel ◽  
Debatosh Das ◽  
Kartikye Varshney ◽  
Markus C. Kolodziej ◽  
José A. Villaécija-Aguilar ◽  
...  
Keyword(s):  
Root Hair ◽  
Lotus Japonicus ◽  
Root Hairs ◽  
Acc Synthase ◽  
Ethylene Biosynthesis ◽  
Dependent Manner ◽  
Ethylene Signaling ◽  
Root Hair Development ◽  
Hair Development ◽  
Developmental Responses

An evolutionarily ancient plant hormone receptor complex comprising the α/β-fold hydrolase receptor KARRIKIN INSENSITIVE 2 (KAI2) and the F-box protein MORE AXILLARY GROWTH 2 (MAX2) mediates a range of developmental responses to smoke-derived butenolides called karrikins (KARs) and to yet elusive endogenous KAI2 ligands (KLs). Degradation of SUPPRESSOR OF MAX2 1 (SMAX1) after ligand perception is considered to be a key step in KAR/KL signaling. However, molecular events which regulate plant development downstream of SMAX1 removal have not been identified. Here we show thatLotus japonicusSMAX1 is specifically degraded in the presence of KAI2 and MAX2 and plays an important role in regulating root and root hair development.smax1mutants display very short primary roots and elongated root hairs. Their root transcriptome reveals elevated ethylene responses and expression ofACC Synthase 7(ACS7), which encodes a rate-limiting enzyme in ethylene biosynthesis.smax1mutants release increased amounts of ethylene and their root phenotype is rescued by treatment with ethylene biosynthesis and signaling inhibitors. KAR treatment inducesACS7expression in a KAI2-dependent manner and root developmental responses to KAR treatment depend on ethylene signaling. Furthermore, inArabidopsis, KAR-induced root hair elongation depends onACS7. Thus, we reveal a connection between KAR/KL and ethylene signaling in which the KAR/KL signaling module (KAI2–MAX2–SMAX1) regulates the biosynthesis of ethylene to fine-tune root and root hair development, which are important for seedling establishment at the beginning of the plant life cycle.

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