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1
Gajek, Katarzyna, Agnieszka Janiak, Urszula Korotko, Beata Chmielewska, Marek Marzec e Iwona Szarejko. "Whole Exome Sequencing-Based Identification of a Novel Gene Involved in Root Hair Development in Barley (Hordeum vulgare L.)". International Journal of Molecular Sciences 22, n. 24 (14 dicembre 2021): 13411. http://dx.doi.org/10.3390/ijms222413411.
Abstract (sommario):
Root hairs play a crucial role in anchoring plants in soil, interaction with microorganisms and nutrient uptake from the rhizosphere. In contrast to Arabidopsis, there is a limited knowledge of root hair morphogenesis in monocots, including barley (Hordeum vulgare L.). We have isolated barley mutant rhp1.e with an abnormal root hair phenotype after chemical mutagenesis of spring cultivar ‘Sebastian’. The development of root hairs was initiated in the mutant but inhibited at the very early stage of tip growth. The length of root hairs reached only 3% of the length of parent cultivar. Using a whole exome sequencing (WES) approach, we identified G1674A mutation in the HORVU1Hr1G077230 gene, located on chromosome 1HL and encoding a cellulose synthase-like C1 protein (HvCSLC1) that might be involved in the xyloglucan (XyG) synthesis in root hairs. The identified mutation led to the retention of the second intron and premature termination of the HvCSLC1 protein. The mutation co-segregated with the abnormal root hair phenotype in the F2 progeny of rhp1.e mutant and its wild-type parent. Additionally, different substitutions in HORVU1Hr1G077230 were found in four other allelic mutants with the same root hair phenotype. Here, we discuss the putative role of HvCSLC1 protein in root hair tube elongation in barley.
2
Tian, Heyang, Hongchun Sun, Lingxiao Zhu, Ke Zhang, Yongjiang Zhang, Haina Zhang, Jijie Zhu et al. "Response of in situ root phenotypes to potassium stress in cotton". PeerJ 11 (21 giugno 2023): e15587. http://dx.doi.org/10.7717/peerj.15587.
Abstract (sommario):
Potassium plays a significant role in the basic functions of plant growth and development. Potassium uptake is closely associated with morphological characteristics of the roots. However, the dynamic characteristics of phenotype and lifespan of cotton (Gossypium hirsutum L.) lateral roots and root hairs under low and high potassium stress remain unclear. In this study, potassium stress experiments (low and high potassium, medium potassium as control) were conducted using RhizoPot (an in situ root observation device) to determine the response characteristics of lateral roots and root hairs in cotton under potassium stress. The plant morphology, photosynthetic characteristics, root phenotypic changes, and lifespan of lateral roots and root hairs were measured. Potassium accumulation, aboveground phenotype, photosynthetic capacity, root length density, root dry weight, root diameter, lateral root lifespan, and root hair lifespan under low potassium stress were significantly decreased compared to medium potassium treatment. However, the root hair length of the former was significantly increased than that of the latter. Potassium accumulation and the lateral root lifespan were significantly increased under high potassium treatment, while root length density, root dry weight, root diameter, root hair length, and root hair lifespan were significantly decreased compared to the medium potassium treatment. Notably, there were no significant differences in aboveground morphology and photosynthetic characters. Principal component analysis revealed that lateral root lifespan, root hair lifespan of the first lateral root, and root hair length significantly correlated with potassium accumulation. The root had similar regularity responses to low and high potassium stress except for lifespan and root hair length. The findings of this study enhance the understanding of the phenotype and lifespan of cotton’s lateral roots and root hairs under low and high potassium stress.
3
Kuběnová, Lenka, Michaela Tichá, Jozef Šamaj e Miroslav Ovečka. "ROOT HAIR DEFECTIVE 2 vesicular delivery to the apical plasma membrane domain during Arabidopsis root hair development". Plant Physiology 188, n. 3 (5 gennaio 2022): 1563–85. http://dx.doi.org/10.1093/plphys/kiab595.
Abstract (sommario):
Abstract Arabidopsis (Arabidopsis thaliana) root hairs develop as long tubular extensions from the rootward pole of trichoblasts and exert polarized tip growth. The establishment and maintenance of root hair polarity is a complex process involving the local apical production of reactive oxygen species generated by A. thaliana nicotinamide adenine dinucleotide phosphate (NADPH) oxidase respiratory burst oxidase homolog protein C/ROOT HAIR-DEFECTIVE 2 (AtRBOHC/RHD2). Loss-of-function root hair defective 2 (rhd2) mutants have short root hairs that are unable to elongate by tip growth, and this phenotype is fully complemented by GREEN FLUORESCENT PROTEIN (GFP)-RHD2 expressed under the RHD2 promoter. However, the spatiotemporal mechanism of AtRBOHC/RHD2 subcellular redistribution and delivery to the plasma membrane (PM) during root hair initiation and tip growth are still unclear. Here, we used advanced microscopy for detailed qualitative and quantitative analysis of vesicular compartments containing GFP-RHD2 and characterization of their movements in developing bulges and growing root hairs. These compartments, identified by an independent molecular marker mCherry-VTI12 as the trans-Golgi network (TGN), deliver GFP-RHD2 to the apical PM domain, the extent of which corresponds with the stage of root hair formation. Movements of TGN/early endosomes, but not late endosomes, were affected in the bulging domains of the rhd2-1 mutant. Finally, we revealed that structural sterols might be involved in the accumulation, docking, and incorporation of TGN compartments containing GFP-RHD2 to the apical PM of root hairs. These results help in clarifying the mechanism of polarized AtRBOHC/RHD2 targeting, maintenance, and recycling at the apical PM domain, coordinated with different developmental stages of root hair initiation and growth.
4
Walker, Simon A., e J. Allan Downie. "Entry of Rhizobium leguminosarum bv. viciae into Root Hairs Requires Minimal Nod Factor Specificity, but Subsequent Infection Thread Growth Requires nodO or nodE". Molecular Plant-Microbe Interactions® 13, n. 7 (luglio 2000): 754–62. http://dx.doi.org/10.1094/mpmi.2000.13.7.754.
Abstract (sommario):
Using various mutant strains of Rhizobium leguminosarum bv. viciae, we have investigated the role of nodO in stimulating infection thread development in vetch and pea. Analysis of R. leguminosarum bv. viciae nodE and nodO mutants revealed no significant difference from the wild-type infection phenotype. Conversely, an R. leguminosarum bv. viciae nodE nodO double mutant was severely impaired in its ability to form normal infection threads. This strain displayed a number of novel infection-related events, including intracellular accumulations of bacteria at the base of root hairs, distended and enlarged infection threads, and reversed threads growing up root hairs. Since normal infection was seen in a nodE mutant, nodO must suppress these abnormal infection phenomena. A deletion mutant, retaining only the nodD and nodABCIJ genes, also formed intracellular accumulations at the base of root hairs. Addition of R. leguminosarum bv. viciae nodO could alleviate this phenotype and restore some infection thread formation, although these threads appeared to be abnormal. Exogenous application of R. leguminosarum bv. viciae Nod factors could not alleviate the aberrant infection phenotype. Our results show that the most basic Nod factor structure can allow bacterial entry into the root hair, and that nodO can promote subsequent infection thread development.
5
Cajero-Sanchez, Wendy, Pamela Aceves-Garcia, María Fernández-Marcos, Crisanto Gutiérrez, Ulises Rosas, Berenice García-Ponce, Elena R. Álvarez-Buylla, Maria de la Paz Sánchez e Adriana Garay-Arroyo. "Natural Root Cellular Variation in Responses to Osmotic Stress in Arabidopsis thaliana Accessions". Genes 10, n. 12 (29 novembre 2019): 983. http://dx.doi.org/10.3390/genes10120983.
Abstract (sommario):
Arabidopsis naturally occurring populations have allowed for the identification of considerable genetic variation remodeled by adaptation to different environments and stress conditions. Water is a key resource that limits plant growth, and its availability is initially sensed by root tissues. The root’s ability to adjust its physiology and morphology under water deficit makes this organ a useful model to understand how plants respond to water stress. Here, we used hyperosmotic shock stress treatments in different Arabidopsis accessions to analyze the root cell morphological responses. We found that osmotic stress conditions reduced root growth and root apical meristem (RAM) size, promoting premature cell differentiation without affecting the stem cell niche morphology. This phenotype was accompanied by a cluster of small epidermal and cortex cells with radial expansion and root hairs at the transition to the elongation zone. We also found this radial expansion with root hairs when plants are grown under hypoosmotic conditions. Finally, root growth was less affected by osmotic stress in the Sg-2 accession followed by Ws, Cvi-0, and Col-0; however, after a strong osmotic stress, Sg-2 and Cvi-0 were the most resilience accessions. The sensitivity differences among these accessions were not explained by stress-related gene expression. This work provides new cellular insights on the Arabidopsis root phenotypic variability and plasticity to osmotic stress.
6
Robledo, Marta, José I. Jiménez-Zurdo, M. José Soto, Encarnación Velázquez, Frank Dazzo, Eustoquio Martínez-Molina e Pedro F. Mateos. "Development of Functional Symbiotic White Clover Root Hairs and Nodules Requires Tightly Regulated Production of Rhizobial Cellulase CelC2". Molecular Plant-Microbe Interactions® 24, n. 7 (luglio 2011): 798–807. http://dx.doi.org/10.1094/mpmi-10-10-0249.
Abstract (sommario):
The establishment of rhizobia as nitrogen-fixing endosymbionts within legume root nodules requires the disruption of the plant cell wall to breach the host barrier at strategic infection sites in the root hair tip and at points of bacterial release from infection threads (IT) within the root cortex. We previously found that Rhizobium leguminosarum bv. trifolii uses its chromosomally encoded CelC2 cellulase to erode the noncrystalline wall at the apex of root hairs, thereby creating the primary portal of its entry into white clover roots. Here, we show that a recombinant derivative of R. leguminosarum bv. trifolii ANU843 that constitutively overproduces the CelC2 enzyme has increased competitiveness in occupying aberrant nodule-like root structures on clover that are inefficient in nitrogen fixation. This aberrant symbiotic phenotype involves an extensive uncontrolled degradation of the host cell walls restricted to the expected infection sites at tips of deformed root hairs and significantly enlarged infection droplets at termini of wider IT within the nodule infection zone. Furthermore, signs of elevated plant host defense as indicated by reactive oxygen species production in root tissues were more evident during infection by the recombinant strain than its wild-type parent. Our data further support the role of the rhizobial CelC2 cell wall–degrading enzyme in primary infection, and show evidence of its importance in secondary symbiotic infection and tight regulation of its production to establish an effective nitrogen-fixing root nodule symbiosis.
7
Kawaguchi, Masayoshi, Haruko Imaizumi-Anraku, Hiroyuki Koiwa, Sinobu Niwa, Akira Ikuta, Kunihiko Syono e Shoichiro Akao. "Root, Root Hair, and Symbiotic Mutants of the Model Legume Lotus japonicus". Molecular Plant-Microbe Interactions® 15, n. 1 (gennaio 2002): 17–26. http://dx.doi.org/10.1094/mpmi.2002.15.1.17.
Abstract (sommario):
To gain an overview of plant factors controlling nodule number and organogenesis, an extensive screening using model legume Lotus japonicus was carried out. This screening involved 40,000 M2 seeds, and 32 stable mutant lines were isolated. From these, 16 mutant lines maintaining the phenotypic variation were selected and genetically analyzed. With respect to nodule number, four loci were identified, Ljsym77, Ljsym78, slippery root (slp), and radial organization1 (rdo1). The former two mutants have an increased number of nodules, while the latter two have a decreased number. Ljsym78-1 and Ljsym78-2 are hypernodulating mutants with a branched root system and were found to be allelic to Ljsym16. The phenotype of the Ljsym77 mutant was highly pleiotropic, being deficient in light and gravity responses. The slp mutant was isolated as a low-nodulating mutant lacking root hairs. Concerning nodule organogenesis, nine symbiotic loci were identified, including the two loci alb1 and fen1. Mutants affecting the developmental process of nodule organogenesis were placed in three phenotypic categories: Nod¯ (Ljsym70 to Ljsym73), Hist¯ (alb1-1, alb1-2, and Ljsym79), and Fix¯ (fen1, Ljsym75, and Ljsym81).
8
Ishizawa, Miku, Kayo Hashimoto, Misato Ohtani, Ryosuke Sano, Yukio Kurihara, Hiroaki Kusano, Taku Demura, Minami Matsui e Kumi Sato-Nara. "Inhibition of Pre-mRNA Splicing Promotes Root Hair Development in Arabidopsis thaliana". Plant and Cell Physiology 60, n. 9 (1 agosto 2019): 1974–85. http://dx.doi.org/10.1093/pcp/pcz150.
Abstract (sommario):
Abstract Root hairs protruding from epidermal cells increase the surface area for water absorption and nutrient uptake. Various environmental factors including light, oxygen concentration, carbon dioxide concentration, calcium and mycorrhizal associations promote root hair formation in Arabidopsis thaliana. Light regulates the expression of a large number of genes at the transcriptional and post-transcriptional levels; however, there is little information linking the light response to root hair development. In this study, we describe a novel mutant, light-sensitive root-hair development 1 (lrh1), that displays enhanced root hair development in response to light. Hypocotyl and root elongation was inhibited in the lrh1 mutant, which had a late flowering phenotype. We identified the gene encoding the p14 protein, a putative component of the splicing factor 3b complex essential for pre-mRNA splicing, as being responsible for the lrh1 phenotype. Indeed, regulation of alternative splicing was affected in lrh1 mutants and treatment with a splicing inhibitor mimicked the lrh1 phenotype. Genome-wide alterations in pre-mRNA splicing patterns including differential splicing events of light signaling- and circadian clock-related genes were found in lrh1 as well as a difference in transcriptional regulation of multiple genes including upregulation of essential genes for root hair development. These results suggest that pre-mRNA splicing is the key mechanism regulating root hair development in response to light signals.
9
Liu, Xin, Lingling Pei, Lingling Zhang, Xueying Zhang e Jing Jiang. "Regulation of miR319b-Targeted SlTCP10 during the Tomato Response to Low-Potassium Stress". International Journal of Molecular Sciences 24, n. 8 (11 aprile 2023): 7058. http://dx.doi.org/10.3390/ijms24087058.
Abstract (sommario):
Potassium deficiency confines root growth and decreases root-to-shoot ratio, thereby limiting root K+ acquisition. This study aimed to identify the regulation network of microRNA319 involved in low-K+ stress tolerance in tomato (Solanum lycopersicum). SlmiR319b-OE roots demonstrated a smaller root system, a lower number of root hairs and lower K+ content under low-K+ stress. We identified SlTCP10 as the target of miR319b using a modified RLM-RACE procedure from some SlTCPs’ predictive complementarity to miR319b. Then, SlTCP10-regulated SlJA2 (an NAC transcription factor) influenced the response to low-K+ stress. CR-SlJA2 (CRISPR-Cas9-SlJA2) lines showed the same root phenotype to SlmiR319-OE compared with WT lines. OE-SlJA2(Overexpression-SlJA2) lines showed higher root biomass, root hair number and K+ concentration in the roots under low-K+ conditions. Furthermore, SlJA2 has been reported to promote abscisic acid (ABA) biosynthesis. Therefore, SlJA2 increases low-K+ tolerance via ABA. In conclusion, enlarging root growth and K+ absorption by the expression of SlmiR319b-regulated SlTCP10, mediating SlJA2 in roots, could provide a new regulation mechanism for increasing K+ acquisition efficiency under low-K+ stress.
10
Wu, Rui, Zhixin Liu, Jiajing Wang, Chenxi Guo, Yaping Zhou, George Bawa, Jean-David Rochaix e Xuwu Sun. "COE2 Is Required for the Root Foraging Response to Nitrogen Limitation". International Journal of Molecular Sciences 23, n. 2 (13 gennaio 2022): 861. http://dx.doi.org/10.3390/ijms23020861.
Abstract (sommario):
There are numerous exchanges of signals and materials between leaves and roots, including nitrogen, which is one of the essential nutrients for plant growth and development. In this study we identified and characterized the Chlorophyll A/B-Binding Protein (CAB) (named coe2 for CAB overexpression 2) mutant, which is defective in the development of chloroplasts and roots under normal growth conditions. The phenotype of coe2 is caused by a mutation in the Nitric Oxide Associated (NOA1) gene that is implicated in a wide range of chloroplast functions including the regulation of metabolism and signaling of nitric oxide (NO). A transcriptome analysis reveals that expression of genes involved in metabolism and lateral root development are strongly altered in coe2 seedlings compared with WT. COE2 is expressed in hypocotyls, roots, root hairs, and root caps. Both the accumulation of NO and the growth of lateral roots are enhanced in WT but not in coe2 under nitrogen limitation. These new findings suggest that COE2-dependent signaling not only coordinates gene expression but also promotes chloroplast development and function by modulating root development and absorption of nitrogen compounds.
11
Carbonnel, Samy, Debatosh Das, Kartikye Varshney, Markus C. Kolodziej, José A. Villaécija-Aguilar e Caroline Gutjahr. "The karrikin signaling regulator SMAX1 controlsLotus japonicusroot and root hair development by suppressing ethylene biosynthesis". Proceedings of the National Academy of Sciences 117, n. 35 (17 agosto 2020): 21757–65. http://dx.doi.org/10.1073/pnas.2006111117.
Abstract (sommario):
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.
12
Yan, Min, Wen Jing, Ni Xu, Like Shen, Qun Zhang e Wenhua Zhang. "Arabidopsis thaliana constitutively active ROP11 interacts with the NADPH oxidase respiratory burst oxidase homologue F to regulate reactive oxygen species production in root hairs". Functional Plant Biology 43, n. 3 (2016): 221. http://dx.doi.org/10.1071/fp15090.
Abstract (sommario):
Reactive oxygen species (ROS) play a key signalling role in cells. Plant NADPH oxidases, also known as respiratory burst oxidase homologues (Rbohs), are well characterised ROS-generating systems. In this study, we found that the constitutively active small guanosine triphosphatase (GTPase) ROP11 (CA-ROP11) interacted with RbohF by using a yeast two-hybrid analysis, a pull-down assay and an in vivo bimolecular fluorescence complementation assay. The mutation of amino acid L336 or L337 in RbohF abolished its interaction with CA-ROP11. Coexpression of CA-ROP11 and wild-type RbohF in Nicotiana benthamiana Domin enhanced ROS production compared with coexpression of CA-ROP11 and mutant RbohF or of dominant negative ROP11 and wild-type RbohF. Moreover, CA-ROP11 overexpression resulted in ROS accumulation and a swollen root hair phenotype in Arabidopsis thaliana (L.) Heynh. The deletion of RbohF partially reduced the increase in ROS in Arabidopsis plants overexpressing CA-ROP11. These results suggest that Arabidopsis ROP11 modulates ROS production by interacting with RbohF in root hairs.
13
Mau, Lisa, Simone Junker, Helena Bochmann, Yeshambel E. Mihiret, Jana M. Kelm, Silvia D. Schrey, Ute Roessner et al. "Root Growth and Architecture of Wheat and Brachypodium Vary in Response to Algal Fertilizer in Soil and Solution". Agronomy 12, n. 2 (23 gennaio 2022): 285. http://dx.doi.org/10.3390/agronomy12020285.
Abstract (sommario):
Alternative, recycled sources for mined phosphorus (P) fertilizers are needed to sustain future crop growth. Quantification of phenotypic adaptations and performance of plants with a recycled nutrient source is required to identify breeding targets and agronomy practices for new fertilization strategies. In this study, we tested the phenotypic responses of wheat (Triticum aestivum) and its genetic model, Brachypodium (Brachypodium distachyon), to dried algal biomass (with algae or high or low mineral P) under three growing conditions (fabricated ecosystems (EcoFABs), hydroponics, and sand). For both species, algal-grown plants had similar shoot biomass to mineral-grown plants, taking up more P than the low mineral P plants. Root phenotypes however were strongly influenced by nutrient form, especially in soilless conditions. Algae promoted the development of shorter and thicker roots, notably first and second order lateral roots. Root hairs were 21% shorter in Brachypodium, but 24% longer in wheat with algae compared to mineral high P. Our results are encouraging to new recycled fertilization strategies, showing algae is a nutrient source to wheat and Brachypodium. Variation in root phenotypes showed algal biomass is sensed by roots and is taken up at a higher amount per root length than mineral P. These phenotypes can be selected and further adapted in phenotype-based breeding for future renewal agriculture systems.
14
Li, Yong, Jianshu Zhu, Lingling Wu, Yanlin Shao, Yunrong Wu e Chuanzao Mao. "Functional Divergence of PIN1 Paralogous Genes in Rice". Plant and Cell Physiology 60, n. 12 (14 agosto 2019): 2720–32. http://dx.doi.org/10.1093/pcp/pcz159.
Abstract (sommario):
Abstract Auxin is a phytohormone that plays an important role in plant growth and development by forming local concentration gradients. The regulation of auxin levels is determined by the activity of auxin efflux carrier protein PIN-formed (PIN). In Arabidopsis thaliana, PIN-formed1 (PIN1) functions in inflorescence and root development. In rice (Oryza sativa L.), there are four PIN1 homologs (OsPIN1a–1d), but their functions remain largely unexplored. Hence, in this study, we created mutant alleles of PIN1 gene—pin1a, pin1b, pin1c, pin1d, pin1a pin1b and pin1c pin1d— using CRISPR/Cas9 technology and used them to study the functions of the four OsPIN1 paralogs in rice. In wild-type rice, all four OsPIN1 genes were relatively highly expressed in the root than in other tissues. Compared with the wild type, the OsPIN1 single mutants had no dramatic phenotypes, but the pin1a pin1b double mutant had shorter shoots and primary roots, fewer crown roots, reduced root gravitropism, longer root hairs and larger panicle branch angle. Furthermore, the pin1c pin1d double mutant showed no observable phenotype at the seedling stage, but showed naked, pin-shape inflorescence at flowering. These data suggest that OsPIN1a and OsPIN1b are involved in root, shoot and inflorescence development in rice, whereas OsPIN1c and OsPIN1d mainly function in panicle formation. Our study provides basic knowledge that will facilitate the study of auxin transport and signaling in rice.
15
Koch, P. J., M. G. Mahoney, G. Cotsarelis, K. Rothenberger, R. M. Lavker e J. R. Stanley. "Desmoglein 3 anchors telogen hair in the follicle". Journal of Cell Science 111, n. 17 (1 settembre 1998): 2529–37. http://dx.doi.org/10.1242/jcs.111.17.2529.
Abstract (sommario):
Little is known about the function of desmosomes in the normal structure and function of hair. Therefore, it was surprising that mice without desmoglein 3 (the autoantigen in pemphigus vulgaris) not only developed mucous membrane and skin lesions like pemphigus patients, but also developed hair loss. Analysis of this phenotype indicated that hair was normal through the first growth phase (‘follicular neogenesis’). Around day 20, however, when the hair follicles entered the resting phase of the hair growth cycle (telogen), mice with a targeted disruption of the desmoglein 3 gene (DSG3-/-) lost hair in a wave-like pattern from the head to the tail. Hair then regrew and was lost again in the same pattern with the next synchronous hair cycle. In adults, hair was lost in patches. Gentle hair pulls with adhesive tape showed that anagen (growing) hairs were firmly anchored in DSG3-/- mice, but telogen hairs came out in clumps compared to that of DSG3+/− and +/+ littermates in which telogen hairs were firmly anchored. Histology of bald skin areas in DSG3-/- mice showed cystic telogen hair follicles without hair shafts. Histology of hair follicles in early telogen, just before clinical hair loss occurred, showed loss of cell adhesion (acantholysis) between the cells surrounding the telogen club and the basal layer of the outer root sheath epithelium. Electron microscopy revealed ‘half-desmosomes’ at the plasma membranes of acantholytic cells. Similar acantholytic histology and ultrastructural findings have been previously reported in skin and mucous membrane lesions of DSG3-/- mice and pemphigus vulgaris patients. Immunoperoxidase staining with an antibody raised against mouse desmoglein 3 showed intense staining on the cell surface of keratinocytes surrounding the telogen hair club in normal mice. Similar staining was seen in human telogen hair with an anti-human desmoglein 3 antibody. Finally, a scalp biopsy from a pemphigus vulgaris patient showed empty telogen hair follicles. These data demonstrate that desmoglein 3 is not only critical for cell adhesion in the deep stratified squamous epithelium, but also for anchoring the telogen hair to the outer root sheath of the follicle and underscore the importance of desmosomes in maintaining the normal structure and function of hair.
16
Naidoo, Y., T. I. Baskin e G. Naidoo. "Ultrastructural Studies of Root Swelling in Mutants of Arabidopsis Thaliana". Microscopy and Microanalysis 7, S2 (agosto 2001): 64–65. http://dx.doi.org/10.1017/s1431927600026398.
Abstract (sommario):
Growth is “anisotropic” when growth rates in different directions are not equal. Anisotropic elongation is controlled by cortical microtubules and cellulose microfibrils of the cell wall. Distorted anisotropic growth results when there are aberrations in either the cellulose network or microtubule cytoskeleton. in this ultrastructural study, the roots of wild type (control) and mutants of Arabidopsis thaliana (L.) Heynh, ecotype Columbia, were compared to determine the role of microtubule organisation, cellulose synthesis and cytokinesis on root expansion.Three mutations, obtained by treating seeds of A. thaliana with ethane-methylsulfonate and backcrossing once to wild type after four selfed generations, were isolated and designated as rsw (radially swollen). These phenotypes are all temperature sensitive, growing and appearing as wild type at 19°C but expressing the mutant phenotype at or above 30°C. Segments of intact root tips from the three mutants and wild type were prepared and examined for TEM with a Jeol 1200EX. The overall appearance of rsw seedlings at 19°C is the same as wild type. At 30°C these phenotypes lead to extensive swelling of the root apex. Despite considerable alteration in the morphology of the root apex, the appearance of the root cap and root hairs seems essentially normal. When mutant roots expressing these phenotypes at 30°C are returned to 19°C, a wild type appearance of the root apex and elongation gradually returns.The primary root of the wild type has a remarkably uniform cellular organisation with regularly arranged dense cytoplasmic cells (Fig. 1). At 19°C, rsw4, rsw6 and rsw7 were indistinguishable from wild type; however, at 30°C, the well-defined anatomy was distorted in all tissues by additional cell walls in unusual positions (Fig. 2).
17
Lestari, Puji, Kyujung Van, Moon Young Kim, Byun-Woo Lee e Suk-Ha Lee. "Newly featured infection events in a supernodulating soybean mutant SS2-2 by Bradyrhizobium japonicum". Canadian Journal of Microbiology 52, n. 4 (1 aprile 2006): 328–35. http://dx.doi.org/10.1139/w05-127.
Abstract (sommario):
Supernodulating soybean (Glycine max L. Merr.) mutant SS2-2 and its wild-type counterpart, Sinpaldalkong 2, were examined for the microstructural events associated with nodule formation and development. SS2-2 produced a substantially higher percentage of curled root hairs than the wild type, especially at 14 days after inoculation with Bradyrhizobium japonicum. In addition, there was new evidence that in SS2-2, B. japonicum also entered through fissures created by the emerging adventitious root primordia. Early steps of nodule ontogeny were faster in SS2-2, and continued development of initiated nodules was more frequent and occurred at a higher frequency than in the wild type. These data suggest that the early expression of autoregulation is facilitated by decreasing the speed of cortical cell development, leading to the subsequent termination of less-developed nodules. The nodules of SS2-2 developed into spherical nodules like those formed on the wild type. In both the wild type and supernodulating mutant, vascular bundles bifurcate from root stele and branch off in the nodule cortex to surround the central infected zone. These findings indicate that SS2-2 has complete endosymbiosis and forms completely developed nodule vascular bundles like the wild type, but that the speed of nodule ontogeny differs between the wild type and SS2-2. Thus, SS2-2 has a novel symbiotic phenotype with regard to nodule organogenesis.Key words: Bradyrhizobium japonicum, early nodule development, Glycine max, root hair curling, supernodulation.
18
Teillet, Alice, Joseph Garcia, Françoise de Billy, Michèle Gherardi, Thierry Huguet, David G. Barker, Fernanda de Carvalho-Niebel e Etienne-Pascal Journet. "api, A Novel Medicago truncatula Symbiotic Mutant Impaired in Nodule Primordium Invasion". Molecular Plant-Microbe Interactions® 21, n. 5 (maggio 2008): 535–46. http://dx.doi.org/10.1094/mpmi-21-5-0535.
Abstract (sommario):
Genetic approaches have proved to be extremely useful in dissecting the complex nitrogen-fixing Rhizobium–legume endosymbiotic association. Here we describe a novel Medicago truncatula mutant called api, whose primary phenotype is the blockage of rhizobial infection just prior to nodule primordium invasion, leading to the formation of large infection pockets within the cortex of noninvaded root outgrowths. The mutant api originally was identified as a double symbiotic mutant associated with a new allele (nip-3) of the NIP/LATD gene, following the screening of an ethylmethane sulphonate–mutagenized population. Detailed characterization of the segregating single api mutant showed that rhizobial infection is also defective at the earlier stage of infection thread (IT) initiation in root hairs, as well as later during IT growth in the small percentage of nodules which overcome the primordium invasion block. Neither modulating ethylene biosynthesis (with L-α-(2-aminoethoxyvinylglycine or 1-aminocyclopropane-1-carboxylic acid) nor reducing ethylene sensitivity in a skl genetic background alters the basic api phenotype, suggesting that API function is not closely linked to ethylene metabolism or signaling. Genetic mapping places the API gene on the upper arm of the M. truncatula linkage group 4, and epistasis analyses show that API functions downstream of BIT1/ERN1 and LIN and upstream of NIP/LATD and the DNF genes.
19
Santos, Mário R., Andreia T. Marques, Jörg D. Becker e Leonilde M. Moreira. "The Sinorhizobium meliloti EmrR Regulator Is Required for Efficient Colonization of Medicago sativa Root Nodules". Molecular Plant-Microbe Interactions® 27, n. 4 (aprile 2014): 388–99. http://dx.doi.org/10.1094/mpmi-09-13-0284-r.
Abstract (sommario):
The nitrogen-fixing bacterium Sinorhizobium meliloti must adapt to diverse conditions encountered during its symbiosis with leguminous plants. We characterized a new symbiotically relevant gene, emrR (SMc03169), whose product belongs to the TetR family of repressors and is divergently transcribed from emrAB genes encoding a putative major facilitator superfamily–type efflux pump. An emrR deletion mutant produced more succinoglycan, displayed increased cell-wall permeability, and exhibited higher tolerance to heat shock. It also showed lower tolerance to acidic conditions, a reduced production of siderophores, and lower motility and biofilm formation. The simultaneous deletion of emrA and emrR genes restored the mentioned traits to the wild-type phenotype, except for survival under heat shock, which was lower than that displayed by the wild-type strain. Furthermore, the ΔemrR mutant as well as the double ΔemrAR mutant was impaired in symbiosis with Medicago sativa; it formed fewer nodules and competed poorly with the wild-type strain for nodule colonization. Expression profiling of the ΔemrR mutant showed decreased expression of genes involved in Nod-factor and rhizobactin biosynthesis and in stress responses. Expression of genes directing the biosynthesis of succinoglycan and other polysaccharides were increased. EmrR may therefore be involved in a regulatory network targeting membrane and cell wall modifications in preparation for colonization of root hairs during symbiosis.
20
Larkin, John C., Jason D. Walker, Agnese C. Bolognesi-Winfield, John C. Gray e Amanda R. Walker. "Allele-Specific Interactions Between ttg and gl1 During Trichome Development in Arabidopsis thaliana". Genetics 151, n. 4 (1 aprile 1999): 1591–604. http://dx.doi.org/10.1093/genetics/151.4.1591.
Abstract (sommario):
Abstract Trichome development in Arabidopsis thaliana is a well-characterized model for the study of plant cell differentiation. Two genes that play an essential role in the initiation of trichome development are GL1 and TTG. Mutations in either gene prevent the initiation of most trichomes. The GL1 gene encodes a myb-related transcription factor. Mutations in TTG are pleiotropic, affecting anthocyanins, root hairs, and seed coat mucilage in addition to trichomes. Six ttg alleles were examined and shown to form a hypomorphic series. The severity of all aspects of the ttg phenotype varied in parallel in this allelic series. The weakest allele, ttg-10, causes frequent clusters of adjacent trichomes, suggesting a role for TTG in inhibiting neighboring cells from choosing the trichome fate. This allele results from a mutation in the 5′-untranslated region of ttg and creates an out-of-frame upstream AUG codon. The ttg-10 allele shows several unusual genetic interactions with the weak hypomorphic gl1-2 allele, including intergenic noncomplementation and a synthetic glabrous phenotype. These interactions are specific for the gl1-2 allele. The implication of these results for current models of trichome development is discussed.
21
Sundberg, J. P., M. H. Rourk, D. Boggess, M. E. Hogan, B. A. Sundberg e A. P. Bertolino. "Angora Mouse Mutation: Altered Hair Cycle, Follicular Dystrophy, Phenotypic Maintenance of Skin Grafts, and Changes in Keratin Expression". Veterinary Pathology 34, n. 3 (maggio 1997): 171–79. http://dx.doi.org/10.1177/030098589703400301.
Abstract (sommario):
Angora is an autosomal recessive mouse mutation caused by a deletion of ∼2 kilobases in the fibroblast growth factor 5 ( Fgf5) gene. Phenotypically, homozygous angora ( Fgf5go/ Fgf5go) mice have excessively long truncal hair and can be differentiated from heterozygous (+/ Fgf5go) and wild-type (+/+) littermates by 21 days of age. Abnormal hair length is due to a prolongation of the anagen phase of the hair cycle of approximately 3 days. In addition, widely scattered hair follicles produce structurally defective hair shafts that twist within the follicle, presumably causing secondary hyperplasia of the outer root sheath and epidermis adjacent to the follicle. These follicular abnormalities were accentuated by immunohistochemical detection of mouse specific keratin 6, a nonspecific marker of epidermal hyperplasia. These abnormalities could be identified from birth throughout life in angora mice genotyped by polymerase chain reaction techniques. Moreover, the long truncal hair phenotype was maintained in skin grafted onto C.B-17/Sz- scid/scid mice that had normal pelage hairs and hair cycles, suggesting that circulating or diffusible humoral factors regulating the mouse hair cycle are not involved in this mutation. The angora mutation provides another useful mouse model for studying the hair cycle and its modulation.
22
Zhang, Xiang-Zhong, De-Xing Luo, Xiao-Hui Bai, Huan-Huan Ding, Meng Liu, Jie Deng, Jing-Wen Mai et al. "Upregulation of TRPC6 Mediated by PAX6 Hypomethylation Is Involved in the Mechanical Allodynia Induced by Chemotherapeutics in Dorsal Root Ganglion". International Journal of Neuropsychopharmacology 23, n. 4 (2 marzo 2020): 257–67. http://dx.doi.org/10.1093/ijnp/pyaa014.
Abstract (sommario):
Abstract Background Although the action mechanism of antineoplastic agents is different, oxaliplatin, paclitaxel, or bortezomib as first-line antineoplastic drugs can induce painful neuropathy. In rodents, mechanical allodynia is a common phenotype of painful neuropathy for 3 chemotherapeutics. However, whether there is a common molecular involved in the different chemotherapeutics-induced painful peripheral neuropathy remains unclear. Methods Mechanical allodynia was tested by von Frey hairs following i.p. injection of vehicle, oxaliplatin, paclitaxel, or bortezomib in Sprague-Dawley rats. Reduced representation bisulfite sequencing and methylated DNA immunoprecipitation were used to detect the change of DNA methylation. Western blot, quantitative polymerase chain reaction, chromatin immunoprecipitation, and immunohistochemistry were employed to explore the molecular mechanisms. Results In 3 chemotherapeutic models, oxaliplatin, paclitaxel, or bortezomib accordantly upregulated the expression of transient receptor potential cation channel, subfamily C6 (TRPC6) mRNA and protein without affecting the DNA methylation level of TRPC6 gene in DRG. Inhibition of TRPC6 by using TRPC6 siRNA (i.t., 10 consecutive days) relieved mechanical allodynia significantly following application of chemotherapeutics. Furthermore, the downregulated recruitment of DNA methyltransferase 3 beta (DNMT3b) at paired box protein 6 (PAX6) gene led to the hypomethylation of PAX6 gene and increased PAX6 expression. Finally, the increased PAX6 via binding to the TPRC6 promoter contributes to the TRPC6 increase and mechanical allodynia following chemotherapeutics treatment. Conclusions The TRPC6 upregulation through DNMT3b-mediated PAX6 gene hypomethylation participated in mechanical allodynia following application of different chemotherapeutic drugs.
23
Humann, Jodi L., Hope T. Ziemkiewicz, Svetlana N. Yurgel e Michael L. Kahn. "Regulatory and DNA Repair Genes Contribute to the Desiccation Resistance of Sinorhizobium meliloti Rm1021". Applied and Environmental Microbiology 75, n. 2 (21 novembre 2008): 446–53. http://dx.doi.org/10.1128/aem.02207-08.
Abstract (sommario):
ABSTRACT Sinorhizobium meliloti can form a nitrogen-fixing symbiotic relationship with alfalfa after bacteria in the soil infect emerging root hairs of the growing plant. To be successful at this, the bacteria must be able to survive in the soil between periods of active plant growth, including when conditions are dry. The ability of S. meliloti to withstand desiccation has been known for years, but genes that contribute to this phenotype have not been identified. Transposon mutagenesis was used in combination with novel screening techniques to identify four desiccation-sensitive mutants of S. meliloti Rm1021. DNA sequencing of the transposon insertion sites identified three genes with regulatory functions (relA, rpoE2, and hpr) and a DNA repair gene (uvrC). Various phenotypes of the mutants were determined, including their behavior on several indicator media and in symbiosis. All of the mutants formed an effective symbiosis with alfalfa. To test the hypothesis that UvrC-related excision repair was important in desiccation resistance, uvrA, uvrB, and uvrC deletion mutants were also constructed. These strains were sensitive to DNA damage induced by UV light and 4-NQO and were also desiccation sensitive. These data indicate that uvr gene-mediated DNA repair and the regulation of stress-induced pathways are important for desiccation resistance.
24
Grierson, Claire, e John Schiefelbein. "Root Hairs". Arabidopsis Book 1 (gennaio 2002): e0060. http://dx.doi.org/10.1199/tab.0060.
25
Grierson, Claire, Erik Nielsen, Tijs Ketelaarc e John Schiefelbein. "Root Hairs". Arabidopsis Book 12 (gennaio 2014): e0172. http://dx.doi.org/10.1199/tab.0172.
26
Kimura, Ushiwatari, Suyama, Tominaga-Wada, Wada e Maruyama-Nakashita. "Contribution of Root Hair Development to Sulfate Uptake in Arabidopsis". Plants 8, n. 4 (19 aprile 2019): 106. http://dx.doi.org/10.3390/plants8040106.
Abstract (sommario):
Root hairs often contribute to nutrient uptake from environments, but the contribution varies among nutrients. In Arabidopsis, two high-affinity sulfate transporters, SULTR1;1 and SULTR1;2, are responsible for sulfate uptake by roots. Their increased expression under sulfur deficiency (−S) stimulates sulfate uptake. Inspired by the higher and lower expression, respectively, of SULTR1;1 in mutants with more (werwolf [wer]) and fewer (caprice [cpc]) root hairs, we examined the contribution of root hairs to sulfate uptake. Sulfate uptake rates were similar among plant lines under both sulfur sufficiency (+S) and −S. Under −S, the expression of SULTR1;1 and SULTR1;2 was negatively correlated with the number of root hairs. These results suggest that both −S-induced SULTR expression and sulfate uptake rates were independent of the number of root hairs. In addition, we observed (1) a negative correlation between primary root lengths and number of root hairs and (2) a greater number of root hairs under −S than under +S. These observations suggested that under both +S and −S, sulfate uptake was influenced by the root biomass rather than the number of root hairs.
27
Green, R. L., J. B. Beard e M. J. Oprisko. "Root Hairs and Root Lengths in Nine Warm-season Turfgrass Genotypes". Journal of the American Society for Horticultural Science 116, n. 6 (novembre 1991): 965–69. http://dx.doi.org/10.21273/jashs.116.6.965.
Abstract (sommario):
Root hairs contributed variously to total root length, ranging from a low of 1% for `Emerald' zoysiagrass (Zoysia japonica Steud. x Z. tenuifolia Willd. ex Trin) and 5% for `Georgia Common' centipedegrass [Eremochloa ophiuroides (Munro.) Hack], to a high of 95% and 89% for `Texturf 10' and `FB 119' bermudagrasses [Cynodon dactylon (L.) Pers.], respectively. Genotypes ranking highest for root lengths with root hairs also ranked highest for root lengths without root hairs and for number of main roots per plant. In terms of root lengths with root hairs, first-order lateral roots contributed more to total root length than root lengths of either main roots or second-order lateral roots for all nine genotypes. Number and length of root hairs arising from either main or lateral roots were not significantly affected by their relative distance from the cap of the main root. `Texturf 10' and `FB 119' bermudagrasses ranked highest for root and root-hair extent.
28
Traas, J. A., P. Braat, A. M. Emons, H. Meekes e J. Derksen. "Microtubules in root hairs". Journal of Cell Science 76, n. 1 (1 giugno 1985): 303–20. http://dx.doi.org/10.1242/jcs.76.1.303.
Abstract (sommario):
The microtubules of root hairs of Raphanus sativus, Lepidium sativum, Equisetum hyemale, Limnobium stoloniferum, Ceratopteris thalictroides, Allium sativum and Urtica dioica were investigated using immunofluorescence and electron microscopy. Arrays of cortical microtubules were observed in all hairs. The microtubules in the hairs show net axial orientations, but in Allium and Urtica helical microtubule patterns are also present. Numerical parameters of microtubules in Raphanus, Equisetum and Limnobium were determined from dry-cleave preparations. The results are discussed with respect to cell wall deposition and cell morphogenesis.
29
Wright, Laura. "Dirty-Root-Hairs-Raw". American Book Review 27, n. 5 (2006): 25–26. http://dx.doi.org/10.1353/abr.2006.0113.
30
Werner, Dietrich, e Andreas Bernd Wolff. "Root Hair Specific Proteins in Glycine max". Zeitschrift für Naturforschung C 42, n. 5 (1 maggio 1987): 537–41. http://dx.doi.org/10.1515/znc-1987-0508.
Abstract (sommario):
Abstract In root hairs from seedlings of Glycine max cultivars, isolated from the root system and com pared with the complete organ, specific soluble proteins have been found. By FPLC chromatography and SDS gel electrophoresis root hair specific proteins with molecular weights of 13, 21, 34, 38 and 42 kDa were separated. Additionally, proteins with molecular weights of 12, 20, 69 and 74 kDa were significantly enriched in root hairs compared to roots without root hairs. By using CNBr activated Sepharose with antibodies against the root system without root hairs, the pres ence of root hair specific proteins was confirmed in extracts from isolated root hair cells. Enrichment of Fe and Ca in some of the proteins from the root hairs is demonstrated. The present knowledge of the biochemical specificity of legume root hairs, the target cells of Rhizobium and Bradyrhizobium infection, is discussed.
31
Galway, M. E., D. C. Lane e J. W. Schiefelbein. "Defective control of growth rate and cell diameter in tip-growing root hairs of the rhd4 mutant of Arabidopsis thaliana". Canadian Journal of Botany 77, n. 4 (28 settembre 1999): 494–507. http://dx.doi.org/10.1139/b99-010.
Abstract (sommario):
A recessive mutation in the RHD4 gene of Arabidopsis thaliana L. affects the control of tip growth in seedling root hairs. Fully grown rhd4 root hairs are half the length of wild-type (WT) hairs. The hairs are wider, and they vary in diameter during tip growth. Light microscopy and motion analysis revealed that rhd4 hairs grow more slowly and that hair growth rate varies more than in WT hairs. Hair diameter increases at the rhd4 hair tips when tip growth slows. Ultrastructural analysis revealed cell wall thickenings in some mutant hairs. WT hairs were grown in a hyperosmotic medium in an attempt to mimic the rhd4 hairs and investigate the control of root hair morphology. Osmotic stress increased WT hair diameter and induced hair bulging and also increased the diameters of rhd4 hairs. Osmotic stress could disrupt tip growth through reduced turgor pressure and (or) reduced concentrations of cytosolic calcium. Together these results indicate that RHD4 is required to maintain a uniform rate of tip growth in root hairs.Key words: Arabidopsis thaliana, cell wall, cryofixation, mutant, root hairs, tip growth.
32
Roberts, DG. "Root-hair structure and development in the seagrass Halophila ovalis (R. Br.) Hook. F". Marine and Freshwater Research 44, n. 1 (1993): 85. http://dx.doi.org/10.1071/mf9930085.
Abstract (sommario):
The seagrass Halophila ovalis normally produces one mature root, covered with a permanent mat of root hairs, per node. In this study, the development of the root hairs increased the effective root surface absorptive area by 215%. Of the root surface examined, 39% was devoted to root-hair production. Epidermal cells that produced root hairs contained more cytoplasm, endoplasmic reticulum and Golgi bodies than did adjacent hairless cells. In addition to appearing to be more metabolically active, root-hair-producing cells had a greater number of plasmodesmatal connections with the underlying outer cortical cells than did adjacent cells that did not produce root hairs. This would suggest that cells that produce root hairs play a more active role in nutrient uptake and exchange than do other cortical cells.
33
Bashan, Yoav, e Hanna Levanony. "Factors affecting adsorption of Azospirillum brasilense Cd to root hairs as compared with root surface of wheat". Canadian Journal of Microbiology 35, n. 10 (1 ottobre 1989): 936–44. http://dx.doi.org/10.1139/m89-155.
Abstract (sommario):
Electron microscopy of wheat (Triticum aestivum) roots inoculated with Azospirillum brasilense Cd revealed massive adsorption of bacterial cells to the root surface and less adsorption to root hairs. Quantitative analysis of A. brasilense Cd adsorption to root surface and to root hairs, confirmed qualitatively by light microscopy observations, revealed a bacterial adsorption ratio of 5 (+2): 1 (root surface: root hairs). Extreme bacterial adsorption ratios were recorded when bacteria were previously grown in the presence of KNO3 (27:1) or when bacterial cells were inoculated under hydroponic plant growth conditions (80:1). Adsorption of A. brasilense Cd to roots was directly related to the bacterial growth phase, with logarithmic phase cultures demonstrating a greater adsorption than stationary phase cultures. Adsorption to root hairs was dependent mainly on the number of root hairs developed under certain growth conditions. When very few root hairs had developed, most of the bacterial cells were adsorbed to the root surface. Factors such as starvation, bacteria grown in culture in the presence of KNO3, addition of several nutrients, and protease or NaEDTA treatments of bacterial cells before the adsorption assay decreased bacterial adsorption to root hairs. Other factors such as microaerophilic growth conditions, addition of several bacterial chemoattractants, and cellulase-treated root hairs enhanced bacterial adsorption. It is proposed that although A. brasilense Cd adsorbed to every part of the root system, more cells adsorbed to the root surface of wheat than to the root hairs.Key words: associative bacteria, Azospirillum, bacterial adsorption, beneficial bacteria, rhizosphere bacteria, root-hair colonization.
34
Wood, Susan M., e William Newcomb. "Nodule morphogenesis: the early infection of Alfalfa (Medicago sativa) root hairs by Rhizobium meliloti". Canadian Journal of Botany 67, n. 10 (1 ottobre 1989): 3108–22. http://dx.doi.org/10.1139/b89-390.
Abstract (sommario):
The growth and development of alfalfa (Medicago sativa) cv. Saranac root hairs and their infection by Rhizobium meliloti strain 102F51 was studied with Smith's interference contrast optics. Uninoculated root hairs grew and matured over a 10-h growth period. The nucleus migrated from a position opposite that of root-hair protrusion at initiation to the base of the root-hair protrusion, then into the growing root hair during the most active phase. When growth was nearly complete, the nucleus assumed a position near the base of the vacuolate root hair. If root hairs were inoculated during the first 2 h of growth after initiation, either "Shepherd's crooks" or root hairs deformed into a tight curl as the tip developed. Some of these Shepherd's rooks later demonstrated typical infection-thread formation. Root hairs that were inoculated between 4 and 6 h after root-hair initiation demonstrated branched growth, with the branch forming opposite the position of the nucleus at the time of infection. Infection threads occasionally formed in either the side branches or tip branches. Root hairs that were older than 6 h at the time of inoculation formed a variety of growth deformations, including ballooning, and elongate, spatulate, spiralling, or intertwined growth. Infections in this population of root hairs were rare.
35
Gehring, Christoph A., Helen R. Irving, Akram A. Kabbara, Roger W. Parish, Nawal M. Boukli e William J. Broughton. "Rapid, Plateau-like Increases in Intracellular Free Calcium Are Associated with Nod-Factor—Induced Root-Hair Deformation". Molecular Plant-Microbe Interactions® 10, n. 7 (settembre 1997): 791–802. http://dx.doi.org/10.1094/mpmi.1997.10.7.791.
Abstract (sommario):
Rhizobia excrete variously substituted lipo-oligosaccha-ride Nod factors into the legume rhizosphere. Homologous legumes respond to these signals through deformation of the root hairs and the development of nodulation foci in the root cortex. Cellular events in root hairs from the susceptible zone of nearly mature root hairs were studied in root segments loaded with the calcium indicators Fura-2 or Fluo-3. Application of 10-9 M Nod factors of the broad-host-range Rhizobium sp. NGR234 to the homologous legume Vigna unguiculata resulted, within seconds, in plateau-like increases in intracellular free calcium ([Ca2+]i) in the root hairs and root epidermal cells. Nod factors of R. meliloti at 10-9 M caused equally rapid increases in [Ca2+]i in the root hairs and epidermal cells of the nonhost V. unguiculata, and also induced root-hair deformation. The chitin tetramer, N-N′-N″-N′″-tetracetylchitotetraose, which represents the backbone of Nod factors, induced neither root-hair deformation nor changes in [Ca2+]i in V. unguiculata. Root hairs and epidermal cells of the nonlegume non-host Arabidopsis thaliana showed neither [Ca2+]i increases nor root-hair deformation in response to both factors.
36
Gulden, Robert H., e J. Kevin Vessey. "Penicillium bilaii inoculation increases root-hair production in field pea". Canadian Journal of Plant Science 80, n. 4 (1 ottobre 2000): 801–4. http://dx.doi.org/10.4141/p99-171.
Abstract (sommario):
Under three levels of phosphorus availability, inoculation of pea plants with Penicillium bilaii in growth pouches had no effect on root length (excluding root hairs), mean root diameter, root-hair diameter, P accumulation or shoot growth. However, inoculation with P. bilaii resulted in a 22% increase in the proportion of root containing root hairs and a 33% increase in the mean root-hair length. Key words: Pea, Penicillium bilaii, Pisum sativum, phosphorus, root hairs, root morphology
37
Crawford, Richard J., e David M. Eissenstat. "748 PB 108 THE RELATIONSHIP BETWEEN ROOT HAIR DEVELOPMENT AND OTHER ROOT ATTRIBUTES IN CITRUS AND CITRUS RELATIVES". HortScience 29, n. 5 (maggio 1994): 540c—540. http://dx.doi.org/10.21273/hortsci.29.5.540c.
Abstract (sommario):
The relationship of genotypic variation in root hair development with root proliferation, mycorrhizal colonization, and specific root length (length / dry mass) was studied in sixteen field-grown citrus relatives. The species varied widely in hair development, root length and mass density, and specific root length. No correlation was found between hair development, mycorrhizal colonization, root proliferation, and specific root length. However, there was a significant correlation (r=.55) between the percentage of total root length with hairs and the percentage of hairs with adhered soil. In a second experiment, the phenotypic plasticity in root hair development was studied in four-citrus rootstooks: Swingle citsumelo, Sour orange, Trifoliate orange and Volkamer lemon. Roots were grow” in either mineral soil or high organic matter media. After eight weeks, root length density and percentage of root length with hairs averaged over all four rootstocks was 232 % and 85 % greater in the organic media than in the mineral soil. Similar to the first experiment the percentage of total root length with hairs was significantly correlated (r=.99) with the percentage of hairs with adhered soil.
38
Park, Nam, Li Xiaohua, Romij Uddin e Sang Park. "Phenolic compound production by different morphological phenotypes in hairy root cultures of Fagopyrum tataricum Gaertn." Archives of Biological Sciences 63, n. 1 (2011): 193–98. http://dx.doi.org/10.2298/abs1101193p.
Abstract (sommario):
Hairy roots were obtained after inoculating sterile young stems of Fagopyrum tataricum with Agrobacterium rhizogenes R1000. The established roots displayed two morphological phenotypes when cultured on hormone-free medium containing Murashige-Skoog salts and vitamins. The thin phenotype had a higher growth rate than the thick phenotype. Further, the phenolic compound content of the thin phenotype was higher than that of the thick phenotype. In terms of their total dry weight, the thin phenotype produced an almost double amount of (-)-epigallocatechin as well as more than 51.5% caffeic acid, 65% chlorogenic acid, and 40% rutin compared to the thick phenotype after 21 days of culture. Therefore, selection of the optimal morphological phenotype of hairy roots of tartary buckwheat is an important factor for improved phenolic compound production.
39
Wang, Liyang, Xuelian Li, Melissa Mang, Uwe Ludewig e Jianbo Shen. "Heterogeneous nutrient supply promotes maize growth and phosphorus acquisition: additive and compensatory effects of lateral roots and root hairs". Annals of Botany 128, n. 4 (26 luglio 2021): 431–40. http://dx.doi.org/10.1093/aob/mcab097.
Abstract (sommario):
Abstract Background and Aims Root proliferation is a response to a heterogeneous nutrient distribution. However, the growth of root hairs in response to heterogeneous nutrients and the relationship between root hairs and lateral roots remain unclear. This study aims to understand the effects of heterogeneous nutrients on root hair growth and the trade-off between root hairs and lateral roots in phosphorus (P) acquisition. Methods Near-isogenic maize lines, the B73 wild type (WT) and the rth3 root hairless mutant, were grown in rhizoboxes with uniform or localized supply of 40 (low) or 140 (high) mg P kg−1 soil. Results Both WT and rth3 had nearly two-fold greater shoot biomass and P content under local than uniform treatment at low P. Significant root proliferation was observed in both WT and rth3 in the nutrient patch, with the WT accompanied by an obvious increase (from 0.7 to 1.2 mm) in root hair length. The root response ratio of rth3 was greater than that of WT at low P, but could not completely compensate for the loss of root hairs. This suggests that plants enhanced P acquisition through complementarity between lateral roots and root hairs, and thus regulated nutrient foraging and shoot growth. The disappearance of WT and rth3 root response differences at high P indicated that the P application reduced the dependence of the plants on specific root traits to obtain nutrients. Conclusions In addition to root proliferation, the root response to a nutrient-rich patch was also accompanied by root hair elongation. The genotypes without root hairs increased their investment in lateral roots in a nutrient-rich patch to compensate for the absence of root hairs, suggesting that plants enhanced nutrient acquisition by regulating the trade-off of complementary root traits.
40
Klamer, Florian, Florian Vogel, Xuelian Li, Hinrich Bremer, Günter Neumann, Benjamin Neuhäuser, Frank Hochholdinger e Uwe Ludewig. "Estimating the importance of maize root hairs in low phosphorus conditions and under drought". Annals of Botany 124, n. 6 (12 febbraio 2019): 961–68. http://dx.doi.org/10.1093/aob/mcz011.
Abstract (sommario):
Abstract Background and Aims Root hairs are single-cell extensions of the epidermis that face into the soil and increase the root–soil contact surface. Root hairs enlarge the rhizosphere radially and are very important for taking up water and sparingly soluble nutrients, such as the poorly soil-mobile phosphate. In order to quantify the importance of root hairs for maize, a mutant and the corresponding wild type were compared. Methods The rth2 maize mutant with very short root hairs was assayed for growth and phosphorus (P) acquisition in a slightly alkaline soil with low P and limited water supply in the absence of mycorrhization and with ample P supply. Key Results Root and shoot growth was additively impaired under P deficiency and drought. Internal P concentrations declined with reduced water and P supply, whereas micronutrients (iron, zinc) were little affected. The very short root hairs in rth2 did not affect internal P concentrations, but the P content of juvenile plants was halved under combined stress. The rth2 plants had more fine roots and increased specific root length, but P mobilization traits (root organic carbon and phosphatase exudation) differed little. Conclusions The results confirm the importance of root hairs for maize P uptake and content, but not for internal P concentrations. Furthermore, the performance of root hair mutants may be biased by secondary effects, such as altered root growth.
41
Laus, M. C., A. A. N. van Brussel e J. W. Kijne. "Role of Cellulose Fibrils and Exopolysaccharides of Rhizobium leguminosarum in Attachment to and Infection of Vicia sativa Root Hairs". Molecular Plant-Microbe Interactions® 18, n. 6 (giugno 2005): 533–38. http://dx.doi.org/10.1094/mpmi-18-0533.
Abstract (sommario):
Infection and subsequent nodulation of legume host plants by the root nodule symbiote Rhizobium leguminosarum usually require attachment of the bacteria to root-hair tips. Bacterial cellulose fibrils have been shown to be involved in this attachment process but appeared not to be essential for successful nodulation. Detailed analysis of Vicia sativa root-hair infection by wild-type Rhizobium leguminosarum RBL5523 and its cellulose fibril-deficient celE mutant showed that wild-type bacteria infected elongated growing root hairs, whereas cellulose-deficient bacteria infected young emerging root hairs. Exopolysaccharide-deficient strains that retained the ability to produce cellulose fibrils could also infect elongated root hairs but infection thread colonization was defective. Cellulose-mediated agglutination of these bacteria in the root-hair curl appeared to prevent entry into the induced infection thread. Infection experiments with V. sativa roots and an extracellular polysaccharide (EPS)- and cellulose-deficient double mutant showed that cellulose-mediated agglutination of the EPS-deficient bacteria in the infection thread was now abolished and that infection thread colonization was partially restored. Interestingly, in this case, infection threads were initiated in root hairs that originated from the cortical cell layers of the root and not in epidermal root hairs. Apparently, surface polysaccharides of R. leguminosarum, such as cellulose fibrils, are determining factors for infection of different developmental stages of root hairs.
42
Lloyd, C. W., e B. Wells. "Microtubules are at the tips of root hairs and form helical patterns corresponding to inner wall fibrils". Journal of Cell Science 75, n. 1 (1 aprile 1985): 225–38. http://dx.doi.org/10.1242/jcs.75.1.225.
Abstract (sommario):
Root hairs have sometimes provided contradictory evidence for microtubule/microfibril parallelism. This tissue was re-examined using optimized conditions for the fixation, before immunofluorescence, of root hairs. In phosphate buffer, microtubules did not enter the apical tip of radish root hairs and were clearly fragmented. However, in an osmotically adjusted microtubule-stabilizing buffer, microtubules were observed within the apical dome and appeared unfragmented. Microtubules are not, therefore, absent from the region where new cell wall is presumed to be generated during tip growth. A spiralling of microtubules was seen at the apices of onion root hairs. Using shadow-cast preparations of macerated radish root hairs, it was confirmed that steeply helical microtubules matched the texture of the inner wall. In onion, the 45 degrees microtubular helices are accompanied by similarly wound inner wall fibrils. Results do not support the view that microtubules are not involved in the oriented deposition of fibrils in root hairs. Instead, they are interpreted in terms of a flexible helical cytoskeleton, which is capable of changing its pitch but is sensitive to fixation conditions.
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Mercado-Blanco, Jesús, e Pilar Prieto. "Bacterial endophytes and root hairs". Plant and Soil 361, n. 1-2 (27 marzo 2012): 301–6. http://dx.doi.org/10.1007/s11104-012-1212-9.
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Peterson, R. Larry, e Melissa L. Farquhar. "Root hairs: Specialized tubular cells extending root surfaces". Botanical Review 62, n. 1 (gennaio 1996): 1–40. http://dx.doi.org/10.1007/bf02868919.
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Sieberer, Björn J., Antonius C. J. Timmers e Anne Mie C. Emons. "Nod Factors Alter the Microtubule Cytoskeleton in Medicago truncatula Root Hairs to Allow Root Hair Reorientation". Molecular Plant-Microbe Interactions® 18, n. 11 (novembre 2005): 1195–204. http://dx.doi.org/10.1094/mpmi-18-1195.
Abstract (sommario):
The microtubule (MT) cytoskeleton is an important part of the tip-growth machinery in legume root hairs. Here we report the effect of Nod factor (NF) on MTs in root hairs of Medicago truncatula. In tip-growing hairs, the ones that typically curl around rhizobia, NF caused a subtle shortening of the endoplasmic MT array, which recovered within 10 min, whereas cortical MTs were not visibly affected. In growth-arresting root hairs, endoplasmic MTs disappeared shortly after NF application, but reformed within 20 min, whereas cortical MTs remained present in a high density. After NF treatment, growth-arresting hairs were swelling at their tips, after which a new outgrowth formed that deviated with a certain angle from the former growth axis. MT depolymerization with oryzalin caused a growth deviation similar to the NF; whereas, combined with NF, oryzalin increased and the MT-stabilizing drug taxol suppressed NF-induced growth deviation. The NF-induced disappearance of the endoplasmic MTs correlated with a loss of polar cytoarchitecture and straight growth directionality, whereas the reappearance of endoplasmic MTs correlated with the new set up of polar cytoarchitecture. Drug studies showed that MTs are involved in determining root hair elongation in a new direction after NF treatment.
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Tortora, Giorgia, Stefano Buratti, Matteo Grenzi, Alex Costa, Andrea Bassi e Alessia Candeo. "Imaging of calcium gradient oscillations in plant root hairs by light sheet fluorescence microscopy". EPJ Web of Conferences 287 (2023): 03012. http://dx.doi.org/10.1051/epjconf/202328703012.
Abstract (sommario):
Root hairs are a delicate single-cell system whose growth is regulated by a fine mechanism characterised by the presence of a tip-high Ca2+ gradient that shows regular oscillations in growing root hairs. We show a method based on the use of Light sheet fluorescence microscopy (LSFM) which allows the quasi-physiological analysis of Arabidopsis thaliana plant roots hairs with excellent spatial and temporal resolution over a wide field of view. We show how the healthy growing root hairs are linked to precise oscillations and how a disruption of this mechanism can be associated to specific genes.
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Hill, J. O., R. J. Simpson, M. H. Ryan e D. F. Chapman. "Root hair morphology and mycorrhizal colonisation of pasture species in response to phosphorus and nitrogen nutrition". Crop and Pasture Science 61, n. 2 (2010): 122. http://dx.doi.org/10.1071/cp09217.
Abstract (sommario):
Root hairs and arbuscular mycorrhizal fungi (AMF) increase the absorptive surface area of a root and the volume of soil explored and as such are important for nutrient acquisition in infertile soil. Root hair morphology and colonisation by AMF were compared for 10 temperate pasture species, and responses to N and P deficiency characterised. Vulpia spp., Holcus lanatus, and Lolium rigidum had the longest root hairs (range 1.02–2.36 mm) while Trifolium subterraneum had the shortest (~0.27 mm). In contrast, T. subterraneum had a much higher density of root hairs than any of the other species. In response to P deficiency, the length and density of root hairs generally increased; in response to N deficiency, both increases and decreases in the length and density of root hairs were observed. The annual dicotyledons T. subterraneum and Arctotheca calendula had much higher mycorrhizal colonisation on roots grown at low P availability than the grasses. Root colonisation decreased with increasing P availability in all species. A yield advantage from mycorrhizal colonisation was demonstrated only for T. subterraneum when P was deficient. The potential root cylinder volume of each species was calculated as an index of the ability of the species to explore soil. Although all plant species were colonised by AMF, a positive linear relationship was observed between relative P uptake rate from the soil and the rate at which potential root cylinder volumes were developed by most species. Development of potential root cylinder volume also largely explained the critical external P requirements of most species. No such relationships were observed for N. It was concluded that knowledge of root length and the length of root hairs grown in nutrient-poor conditions may be used to predict the potential of many plant species to acquire P, and also their critical external P requirement for maximum growth. However, the study also highlighted some exceptional species.
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Charest, P. J., D. Stewart e P. L. Budicky. "Root induction in hybrid poplar by Agrobacterium genetic transformation". Canadian Journal of Forest Research 22, n. 12 (1 dicembre 1992): 1832–37. http://dx.doi.org/10.1139/x92-239.
Abstract (sommario):
Three Agrobacteriumrhizogenes strains (A4, 8196, and ATC39207) and two Agrobacteriumtumefaciens mutant strains (A208 (pTiT37•14a/a) and C58 (pGV3297)) were evaluated for their genetic transformation frequency invitro on cuttings of Populusdeltoides × nigra line DN106 and Populusnigra × maximowiczii lines NM1 and NM6. The aim of this work was to increase biomass production by genetically modifying hybrid poplar root systems. Inoculation of the cut end of invitro grown stems with the A. rhizogenes strain ATC39207 gave the highest frequency of typical hairy root formation with line DN106. The other combinations of Agrobacterium strains and poplar lines yielded very low frequencies of hairy root induction or induction of tumours instead of hairy roots. Similar attempts with greenhouse-grown plants gave negative results. The modified root system resulting from the invitro inoculation of line DN106 cuttings yielded an increase in root and aerial biomass production after 175 days of growth invitro. Preliminary data confirm this observation in the greenhouse. Genetic transformation of the tissues was proven by phenotype (hairy root or tumour), hormone autotrophy, and opine production in the resulting tissues. Because of the host range restriction and inefficiency of this approach, it is not practical at this time for use in the transformation of hybrid poplar.
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Wan, Jinrong, Michael Torres, Ashwin Ganapathy, Jay Thelen, Beverly B. DaGue, Brian Mooney, Dong Xu e Gary Stacey. "Proteomic Analysis of Soybean Root Hairs After Infection by Bradyrhizobium japonicum". Molecular Plant-Microbe Interactions® 18, n. 5 (maggio 2005): 458–67. http://dx.doi.org/10.1094/mpmi-18-0458.
Abstract (sommario):
Infection of soybean root hairs by Bradyrhizobium japonicum is the first of several complex events leading to nodulation. In the current proteomic study, soybean root hairs after inoculation with B. japonicum were separated from roots. Total proteins were analyzed by two-dimensional (2-D) polyacrylamide gel electrophoresis. In one experiment, 96 protein spots were analyzed by matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry (MS) to compare protein profiles between uninoculated roots and root hairs. Another 37 spots, derived from inoculated root hairs over different timepoints, were also analyzed by tandem MS (MS/MS). As expected, some proteins were differentially expressed in root hairs compared with roots (e.g., a chitinase and phosphoenolpyruvate carboxylase). Out of 37 spots analyzed by MS/MS, 27 candidate proteins were identified by database comparisons. These included several proteins known to respond to rhizobial inoculation (e.g., peroxidase and phenylalanine-ammonia lyase). However, novel proteins were also identified (e.g., phospholipase D and phosphoglucomutase). This research establishes an excellent system for the study of root-hair infection by rhizobia and, in a more general sense, the functional genomics of a single, plant cell type. The results obtained also indicate that proteomic studies with soybean, lacking a complete genome sequence, are practical.
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Nguyen, Tran Hong Nha, Laurent Brechenmacher, Joshua T. Aldrich, Therese R. Clauss, Marina A. Gritsenko, Kim K. Hixson, Marc Libault et al. "Quantitative Phosphoproteomic Analysis of Soybean Root Hairs Inoculated with Bradyrhizobium japonicum". Molecular & Cellular Proteomics 11, n. 11 (25 luglio 2012): 1140–55. http://dx.doi.org/10.1074/mcp.m112.018028.
Abstract (sommario):
Root hairs are single hair-forming cells on roots that function to increase root surface area, enhancing water and nutrient uptake. In leguminous plants, root hairs also play a critical role as the site of infection by symbiotic nitrogen fixing rhizobia, leading to the formation of a novel organ, the nodule. The initial steps in the rhizobia-root hair infection process are known to involve specific receptor kinases and subsequent kinase cascades. Here, we characterize the phosphoproteome of the root hairs and the corresponding stripped roots (i.e. roots from which root hairs were removed) during rhizobial colonization and infection to gain insight into the molecular mechanism of root hair cell biology. We chose soybean (Glycine max L.), one of the most important crop plants in the legume family, for this study because of its larger root size, which permits isolation of sufficient root hair material for phosphoproteomic analysis. Phosphopeptides derived from root hairs and stripped roots, mock inoculated or inoculated with the soybean-specific rhizobium Bradyrhizobium japonicum, were labeled with the isobaric tag eight-plex iTRAQ, enriched using Ni-NTA magnetic beads and subjected to nanoRPLC-MS/MS1 analysis using HCD and decision tree guided CID/ETD strategy. A total of 1625 unique phosphopeptides, spanning 1659 nonredundant phosphorylation sites, were detected from 1126 soybean phosphoproteins. Among them, 273 phosphopeptides corresponding to 240 phosphoproteins were found to be significantly regulated (>1.5-fold abundance change) in response to inoculation with B. japonicum. The data reveal unique features of the soybean root hair phosphoproteome, including root hair and stripped root-specific phosphorylation suggesting a complex network of kinase-substrate and phosphatase-substrate interactions in response to rhizobial inoculation.