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Plant Physiology Nov 2021Abiotic stresses increasingly threaten existing ecological and agricultural systems across the globe. Plant roots perceive these stresses in the soil and adapt their... (Review)
Review
Abiotic stresses increasingly threaten existing ecological and agricultural systems across the globe. Plant roots perceive these stresses in the soil and adapt their architecture accordingly. This review provides insights into recent discoveries showing the importance of root system architecture (RSA) and plasticity for the survival and development of plants under heat, cold, drought, salt, and flooding stress. In addition, we review the molecular regulation and hormonal pathways involved in controlling RSA plasticity, main root growth, branching and lateral root growth, root hair development, and formation of adventitious roots. Several stresses affect root anatomy by causing aerenchyma formation, lignin and suberin deposition, and Casparian strip modulation. Roots can also actively grow toward favorable soil conditions and avoid environments detrimental to their development. Recent advances in understanding the cellular mechanisms behind these different root tropisms are discussed. Understanding root plasticity will be instrumental for the development of crops that are resilient in the face of abiotic stress.
Topics: Adaptation, Physiological; Agriculture; Cell Plasticity; Cold Temperature; Crops, Agricultural; Droughts; Floods; Hot Temperature; Plant Growth Regulators; Plant Roots; Soil; Stress, Physiological
PubMed: 34734279
DOI: 10.1093/plphys/kiab392 -
Science (New York, N.Y.) Nov 2020Optimal plant growth is hampered by deficiency of the essential macronutrient phosphate in most soils. Plant roots can, however, increase their root hair density to...
Optimal plant growth is hampered by deficiency of the essential macronutrient phosphate in most soils. Plant roots can, however, increase their root hair density to efficiently forage the soil for this immobile nutrient. By generating and exploiting a high-resolution single-cell gene expression atlas of roots, we show an enrichment of TARGET OF MONOPTEROS 5/LONESOME HIGHWAY (TMO5/LHW) target gene responses in root hair cells. The TMO5/LHW heterodimer triggers biosynthesis of mobile cytokinin in vascular cells and increases root hair density during low-phosphate conditions by modifying both the length and cell fate of epidermal cells. Moreover, root hair responses in phosphate-deprived conditions are TMO5- and cytokinin-dependent. Cytokinin signaling links root hair responses in the epidermis to perception of phosphate depletion in vascular cells.
Topics: Arabidopsis; Arabidopsis Proteins; Basic Helix-Loop-Helix Transcription Factors; Cytokinins; Meristem; Phloem; Phosphates; Plant Epidermis; Plant Roots; Trans-Activators; Xylem
PubMed: 32943451
DOI: 10.1126/science.aay4970 -
Plant Physiology Apr 2019Single-cell RNA sequencing (scRNA-seq) has been used extensively to study cell-specific gene expression in animals, but it has not been widely applied to plants. Here,...
Single-cell RNA sequencing (scRNA-seq) has been used extensively to study cell-specific gene expression in animals, but it has not been widely applied to plants. Here, we describe the use of a commercially available droplet-based microfluidics platform for high-throughput scRNA-seq to obtain single-cell transcriptomes from protoplasts of more than 10,000 Arabidopsis () root cells. We find that all major tissues and developmental stages are represented in this single-cell transcriptome population. Further, distinct subpopulations and rare cell types, including putative quiescent center cells, were identified. A focused analysis of root epidermal cell transcriptomes defined developmental trajectories for individual cells progressing from meristematic through mature stages of root-hair and nonhair cell differentiation. In addition, single-cell transcriptomes were obtained from root epidermis mutants, enabling a comparative analysis of gene expression at single-cell resolution and providing an unprecedented view of the impact of the mutated genes. Overall, this study demonstrates the feasibility and utility of scRNA-seq in plants and provides a first-generation gene expression map of the Arabidopsis root at single-cell resolution.
Topics: Arabidopsis; Feasibility Studies; Plant Epidermis; Plant Roots; Protoplasts; Sequence Analysis, RNA; Single-Cell Analysis; Transcriptome
PubMed: 30718350
DOI: 10.1104/pp.18.01482 -
International Journal of Molecular... Nov 2018Roots are important plant ground organs, which absorb water and nutrients to control plant growth and development. Phytohormones have been known to play a crucial role... (Review)
Review
Roots are important plant ground organs, which absorb water and nutrients to control plant growth and development. Phytohormones have been known to play a crucial role in the regulation of root growth, such as auxin and ethylene, which are central regulators of this process. Recent findings have revealed that root development and elongation regulated by ethylene are auxin dependent through alterations of auxin biosynthesis, transport and signaling. In this review, we focus on the recent advances in the study of auxin and auxin⁻ethylene crosstalk in plant root development, demonstrating that auxin and ethylene act synergistically to control primary root and root hair growth, but function antagonistically in lateral root formation. Moreover, ethylene modulates auxin biosynthesis, transport and signaling to fine-tune root growth and development. Thus, this review steps up the understanding of the regulation of auxin and ethylene in root growth.
Topics: Ethylenes; Indoleacetic Acids; Models, Biological; Plant Roots
PubMed: 30463285
DOI: 10.3390/ijms19113656 -
Acta Biochimica Polonica Oct 2020Chemically, the Nod factors (NFs) are lipochitooligosaccharides, produced mainly by bacteria of the Rhizobium genus. They are the main signaling molecules involved in... (Review)
Review
Chemically, the Nod factors (NFs) are lipochitooligosaccharides, produced mainly by bacteria of the Rhizobium genus. They are the main signaling molecules involved in the initiation of symbiosis between rhizobia and legume plants. Nod factors affect plant tissues at very low concentrations, even as low as 10-12 mol/L. They induce root hair deformation, cortical cell division, and root nodules' formation in the host plant. At the molecular level, the cytoskeleton is reorganized and expression of genes encoding proteins called nodulins is induced in response to Nod factors in the cell. Action of Nod factors is highly specific because it depends on the structure of a particular Nod factor involved, as well as the plant receptor reacting with it.
Topics: Cytoskeleton; Fabaceae; Gene Expression Regulation, Plant; Gibberellins; Indoleacetic Acids; Lipopolysaccharides; Membrane Proteins; Plant Cells; Plant Growth Regulators; Plant Proteins; Plant Root Nodulation; Plant Roots; Protein Isoforms; Rhizobium; Signal Transduction; Symbiosis
PubMed: 33090749
DOI: 10.18388/abp.2020_5353 -
Journal of Experimental Botany Apr 2020The main functions of plant roots are water and nutrient uptake, soil anchorage, and interaction with soil-living biota. Root hairs, single cell tubular extensions of... (Review)
Review
The main functions of plant roots are water and nutrient uptake, soil anchorage, and interaction with soil-living biota. Root hairs, single cell tubular extensions of root epidermal cells, facilitate or enhance these functions by drastically enlarging the absorptive surface. Root hair development is constantly adapted to changes in the root's surroundings, allowing for optimization of root functionality in heterogeneous soil environments. The underlying molecular pathway is the result of a complex interplay between position-dependent signalling and feedback loops. Phytohormone signalling interconnects this root hair signalling cascade with biotic and abiotic changes in the rhizosphere, enabling dynamic hormone-driven changes in root hair growth, density, length, and morphology. This review critically discusses the influence of the major plant hormones on root hair development, and how changes in rhizosphere properties impact on the latter.
Topics: Arabidopsis; Arabidopsis Proteins; Organogenesis, Plant; Plant Growth Regulators; Plant Roots
PubMed: 31993645
DOI: 10.1093/jxb/eraa048 -
Current Opinion in Plant Biology Feb 2018Plant roots control uptake of water and nutrients and cope with environmental challenges. The root epidermis provides the first selective interface for nutrient... (Review)
Review
Plant roots control uptake of water and nutrients and cope with environmental challenges. The root epidermis provides the first selective interface for nutrient absorption, while the endodermis produces the main apoplastic diffusion barrier in the form of a structure called the Casparian strip. The positioning of root hairs on epidermal cells, and of the Casparian strip around endodermal cells, requires asymmetries along cellular axes (cell polarity). Cell polarity is termed planar polarity, when coordinated within the plane of a given tissue layer. Here, we review recent molecular advances towards understanding both the polar positioning of the proteo-lipid membrane domain instructing root hair initiation, and the cytoskeletal, trafficking and polar tethering requirements of proteins at outer or inner plasma membrane domains. Finally, we highlight progress towards understanding mechanisms of Casparian strip formation and underlying endodermal cell polarity.
Topics: Arabidopsis; Biological Transport; Cell Differentiation; Cell Membrane; Cell Polarity; Cell Wall; Cytoskeleton; Plant Roots; Protein Transport
PubMed: 28869926
DOI: 10.1016/j.pbi.2017.08.002 -
International Journal of Molecular... Aug 2020Phosphate is an essential macro-element for plant growth accumulated in the topsoil. The improvement of phosphate uptake efficiency via manually manipulating root system... (Review)
Review
Phosphate is an essential macro-element for plant growth accumulated in the topsoil. The improvement of phosphate uptake efficiency via manually manipulating root system architecture is of vital agronomic importance. This review discusses the molecular mechanisms of root patterning in response to external phosphate availability, which could be applied on the alleviation of phosphate-starvation stress. During the long time evolution, plants have formed sophisticated mechanisms to adapt to environmental phosphate conditions. In terms of root systems, plants would adjust their root system architecture via the regulation of the length of primary root, the length/density of lateral root and root hair and crown root growth angle to cope with different phosphate conditions. Finally, plants develop shallow or deep root system in low or high phosphate conditions, respectively. The plasticity of root system architecture responds to the local phosphate concentrations and this response was regulated by actin filaments, post-translational modification and phytohormones such as auxin, ethylene and cytokinin. This review summarizes the recent progress of adaptive response to external phosphate with focus on integrated physiological, cellular and molecular signaling transduction in rice and .
Topics: Actins; Adaptation, Physiological; Arabidopsis; Indoleacetic Acids; Oryza; Phosphates; Plant Proteins; Plant Roots; Stress, Physiological
PubMed: 32824996
DOI: 10.3390/ijms21175955 -
Journal of Experimental Botany Jul 2020Nitrogen (N) is one of the most important macronutrients for plant growth and development. However, the concentration and distribution of N varies in soil due to a... (Review)
Review
Nitrogen (N) is one of the most important macronutrients for plant growth and development. However, the concentration and distribution of N varies in soil due to a variety of environmental factors. In response, higher plants have evolved a developmentally flexible root system to efficiently take up N under N-limited conditions. Over the past decade, significant progress has been made in understanding this form of plant 'root-foraging' behavior, which is controlled by both a local and a long-distance systemic nitrate signaling pathway. In this review, we focus on the key components of nitrate perception, signaling, and transduction and its role in lateral root development. We also highlight recent findings on the molecular mechanisms of the nitrate systemic signaling pathway, including small signaling peptides involved in long-distance shoot-root communication. Furthermore, we summarize the transcription factor networks responsible for nitrate-dependent lateral root and root hair development.
Topics: Arabidopsis; Gene Expression Regulation, Plant; Nitrates; Nitrogen; Plant Roots; Signal Transduction
PubMed: 31796961
DOI: 10.1093/jxb/erz536 -
Plant Physiology Jul 2016Root hair cells and pollen tubes, like fungal hyphae, possess a typical tip or polar cell expansion with growth limited to the apical dome. Cell expansion needs to be... (Review)
Review
Root hair cells and pollen tubes, like fungal hyphae, possess a typical tip or polar cell expansion with growth limited to the apical dome. Cell expansion needs to be carefully regulated to produce a correct shape and size. Polar cell growth is sustained by oscillatory feedback loops comprising three main components that together play an important role regulating this process. One of the main components are reactive oxygen species (ROS) that, together with calcium ions (Ca(2+)) and pH, sustain polar growth over time. Apoplastic ROS homeostasis controlled by NADPH oxidases as well as by secreted type III peroxidases has a great impact on cell wall properties during cell expansion. Polar growth needs to balance a focused secretion of new materials in an extending but still rigid cell wall in order to contain turgor pressure. In this review, we discuss the gaps in our understanding of how ROS impact on the oscillatory Ca(2+) and pH signatures that, coordinately, allow root hair cells and pollen tubes to expand in a controlled manner to several hundred times their original size toward specific signals.
Topics: Calcium; Cell Membrane; Cell Polarity; Cytoplasm; Homeostasis; Hydrogen-Ion Concentration; Peroxidases; Plant Cells; Plant Proteins; Plant Roots; Pollen Tube; Reactive Oxygen Species
PubMed: 27208283
DOI: 10.1104/pp.16.00191