Imaging local soil kinematics during the first days of maize root growth in sand

AbstractMaize seedlings are grown in Hostun sand with two different gradings and two different densities. The root-soil system is imaged daily for the first 8 days of plant growth with X-ray computed tomography. Segmentation, skeletonisation and digital image correlation techniques are used to analyse the evolution of the root system architecture, the displacement fields and the local strain fields due to plant growth in the soil. It is found that root thickness and root length density do not depend on the initial soil configuration. However, the depth of the root tip is strongly influenced by the initial soil density, and the number of laterals is impacted by grain size, which controls pore size, capillary rise and thus root access to water. Consequently, shorter root axes are observed in denser sand and fewer second order roots are observed in coarser sands. In all soil configurations tested, root growth induces shear strain in the soil around the root system, and locally, in the vicinity of the first order roots axis. Root-induced shear is accompanied by dilative volumetric strain close to the root body. Further away, the soil experiences dilation in denser sand and compaction in looser sand. These results suggest that the increase of porosity close to the roots can be caused by a mix of shear strain and steric exclusion.

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Paenibacillus polymyxa Invades Plant Roots and Forms Biofilms

Applied and Environmental Microbiology ◽

10.1128/aem.71.11.7292-7300.2005 ◽

2005 ◽

Vol 71 (11) ◽

pp. 7292-7300 ◽

Cited By ~ 200

Author(s):

Salme Timmusk ◽

Nina Grantcharova ◽

E. Gerhart H. Wagner

Keyword(s):

Plant Growth ◽

Fluorescent Protein ◽

Paenibacillus Polymyxa ◽

Plant Roots ◽

Root Tip ◽

Broad Host Range ◽

Plant Growth Promoting Bacteria ◽

Soil System ◽

Plant Growth Promoting ◽

Growth Promoting

ABSTRACT Paenibacillus polymyxa is a plant growth-promoting rhizobacterium with a broad host range, but so far the use of this organism as a biocontrol agent has not been very efficient. In previous work we showed that this bacterium protects Arabidopsis thaliana against pathogens and abiotic stress (S. Timmusk and E. G. H. Wagner, Mol. Plant-Microbe Interact. 12:951-959, 1999; S. Timmusk, P. van West, N. A. R. Gow, and E. G. H. Wagner, p. 1-28, in Mechanism of action of the plant growth promoting bacterium Paenibacillus polymyxa, 2003). Here, we studied colonization of plant roots by a natural isolate of P. polymyxa which had been tagged with a plasmid-borne gfp gene. Fluorescence microscopy and electron scanning microscopy indicated that the bacteria colonized predominantly the root tip, where they formed biofilms. Accumulation of bacteria was observed in the intercellular spaces outside the vascular cylinder. Systemic spreading did not occur, as indicated by the absence of bacteria in aerial tissues. Studies were performed in both a gnotobiotic system and a soil system. The fact that similar observations were made in both systems suggests that colonization by this bacterium can be studied in a more defined system. Problems associated with green fluorescent protein tagging of natural isolates and deleterious effects of the plant growth-promoting bacteria are discussed.

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Chickpea (Cicer arietinum L.) root system architecture adaptation to initial soil moisture improves seed development in dry-down conditions

10.1101/2020.09.24.311753 ◽

2020 ◽

Author(s):

Thibaut Bontpart ◽

Ingrid Robertson ◽

Valerio Giuffrida ◽

Cristobal Concha ◽

Livia C. T. Scorza ◽

...

Keyword(s):

Soil Moisture ◽

Root Growth ◽

Root System ◽

Seed Development ◽

Water Use ◽

System Architecture ◽

Adaptive Strategies ◽

Root System Architecture ◽

Initial Soil Moisture ◽

Initial Soil

AbstractSoil water deficit (WD) impacts vascular plant phenology, morpho-physiology, and reproduction. Chickpea, which is mainly grown in semi-arid areas, is a good model plant to dissect mechanisms involved in drought resistance.We used a rhizobox-based phenotyping system to simultaneously and non-destructively characterise root system architecture (RSA) dynamics and water use (WU) patterns. We compared the drought-adaptive strategies of ‘Teketay’ to the drought-sensitive genotype ICC 1882 in high and low initial soil moisture without subsequent irrigation.WD restricted vegetative and reproductive organ biomass for both genotypes. Teketay displayed greater adaptability for RSA dynamics and WU patterns and revealed different drought adaptive strategies depending on initial soil moisture: escape when high, postponement when low. These strategies were manifested in distinct RSA dynamics: in low initial soil moisture, its reduced root growth at the end of the vegetative phase was followed by increased root growth in deeper, wetter soil strata, which facilitated timely WU for seed development and produced better-developed seeds.We demonstrate that RSA adaptation to initial soil moisture is one mechanism by which plants can tolerate WD conditions and ensure reproduction by producing well-developed seeds. Our approach will help in identifying the genetic basis for large plasticity of RSA dynamics which enhances the resilience with which crops can optimally adapt to various drought scenarios.HighlightRoot system architecture and water use patterns change dynamically for distinct drought adaptation strategies in chickpea.

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Garlic Mustard (Alliaria petiolata) Removal Method Affects Native Establishment

Invasive Plant Science and Management ◽

10.1614/ipsm-09-011.1 ◽

2009 ◽

Vol 2 (3) ◽

pp. 230-236 ◽

Cited By ~ 9

Author(s):

E. Kathryn Barto ◽

Don Cipollini

Keyword(s):

Fractal Dimension ◽

Activated Carbon ◽

Plant Growth ◽

Root Growth ◽

Root System ◽

Mycorrhizal Fungi ◽

Alliaria Petiolata ◽

First Year ◽

Garlic Mustard ◽

Entire Plant

AbstractWe used a growth chamber experiment with first-year garlic mustard plants to explore the effects of three garlic mustard removal techniques (treatment with glyphosate, pulling out the entire plant, and clipping the shoot) on growth of the native herb pale jewelweed and its associated mycorrhizal fungi. We also explored the effects of activated carbon and mycorrhizal inocula amendments. We monitored plant height, intra- and extraradical mycorrhizal structures, root growth, and the fractal dimension of the root system. Removing as much garlic mustard root tissue as possible by hand pulling plants led to larger jewelweed plants than other removal methods. Activated carbon and mycorrhizal inocula did not improve plant growth.

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Root-reinforced sand: kinematic response of the soil

E3S Web of Conferences ◽

10.1051/e3sconf/20199212011 ◽

2019 ◽

Vol 92 ◽

pp. 12011

Author(s):

Floriana Anselmucci ◽

Edward Andó ◽

Luc Sibille ◽

Nicolas Lenoir ◽

Robert Peyroux ◽

...

Keyword(s):

Root Growth ◽

Root System ◽

Solid Phase ◽

Image Correlation ◽

Displacement Fields ◽

X Ray ◽

Soil Microstructure ◽

Maize Seeds ◽

Growth Changes

The influence of the soil on the growth of a root system has been largely investigated. By contrast, the aim of this work is to go deep into the details of how the soil may be influenced by the root system. In particular, the root growth process and its potential to improve the soil strength is explored. Even though roots can be seen as fiber-like reinforcements, their growth changes the soil microstructure. Consequently, one of the objectives is to understand how the water content and the soil displacement fields evolve when an inclusion expands radially and axially. In particular, an investigation was carried on to characterise the deformation of the solid phase of the soil, due to the root growth. A series of in-vivo x-ray tomographies was acquired with Maize seeds growing roots into a coarse Hostun HN1.5-2 sand. Digital Image Correlation is used to calculate the soil 3D displacement fields around the growing plant roots.

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Reactive Oxygen Species Link Gene Regulatory Networks During Arabidopsis Root Development

Frontiers in Plant Science ◽

10.3389/fpls.2021.660274 ◽

2021 ◽

Vol 12 ◽

Author(s):

Kosuke Mase ◽

Hironaka Tsukagoshi

Keyword(s):

Reactive Oxygen Species ◽

Plant Growth ◽

Root Growth ◽

Root Development ◽

Control Cell ◽

Reactive Oxygen ◽

Signaling Molecules ◽

Root Tip ◽

Oxygen Species

Plant development under altered nutritional status and environmental conditions and during attack from invaders is highly regulated by plant hormones at the molecular level by various signaling pathways. Previously, reactive oxygen species (ROS) were believed to be harmful as they cause oxidative damage to cells; however, in the last decade, the essential role of ROS as signaling molecules regulating plant growth has been revealed. Plant roots accumulate relatively high levels of ROS, and thus, maintaining ROS homeostasis, which has been shown to regulate the balance between cell proliferation and differentiation at the root tip, is important for proper root growth. However, when the balance is disturbed, plants are unable to respond to the changes in the surrounding conditions and cannot grow and survive. Moreover, ROS control cell expansion and cell differentiation processes such as root hair formation and lateral root development. In these processes, the transcription factor-mediated gene expression network is important downstream of ROS. Although ROS can independently regulate root growth to some extent, a complex crosstalk occurs between ROS and other signaling molecules. Hormone signals are known to regulate root growth, and ROS are thought to merge with these signals. In fact, the crosstalk between ROS and these hormones has been elucidated, and the central transcription factors that act as a hub between these signals have been identified. In addition, ROS are known to act as important signaling factors in plant immune responses; however, how they also regulate plant growth is not clear. Recent studies have strongly indicated that ROS link these two events. In this review, we describe and discuss the role of ROS signaling in root development, with a particular focus on transcriptional regulation. We also summarize the crosstalk with other signals and discuss the importance of ROS as signaling molecules for plant root development.

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Maize nodal root growth under water deficits

10.32469/10355/62393 ◽

2016 ◽

Author(s):

◽

Kara J. Riggs

Keyword(s):

Root Growth ◽

Water Potential ◽

Root System ◽

Soil Water ◽

Soil Water Potential ◽

Experimental System ◽

Root Tip ◽

Growth Responses ◽

Water Potentials ◽

Nodal Root

The nodal root system is critical for the development of the mature root system in maize (Zea mays L.) and other grasses. Under drought conditions, nodal root axes may need to grow through surface soil that is dry, hard, and hot. These roots are known to have a superior ability to continue elongation at low water potentials relative to other organs of the plant, but the physiology of this response has been little studied. The objective of this study was to develop an experimental system that models the field situation in which upper soil layers dry, to enable studies of nodal root growth regulation under water deficit conditions. A divided-chamber experimental system was developed to allow the growth of maize primary and seminal root systems in well-watered conditions while the nodal root system is exposed to precise conditions of low soil water potential. The divided-chamber system was used to characterize nodal root growth responses to a range of soil water potentials under steady-state and reproducible conditions. Two contrasting genotypes, selected for differences in root growth response to water stress based on a previous study of the primary root, displayed similarly sensitive growth responses to -0.3 MPa soil, but different capacities to maintain high root tip water potential corresponding with different growth responses at lower soil water potentials. Both genotypes maintained relatively high nodal root tip water potentials in -2.0 MPa soil, despite the decreased soil water potential, suggesting a stress-induced response that enhances water transport to the root tip. The difference in high tissue water potential maintenance was seen not only between the contrasting genotypes but also between the first two developmental nodes of roots. The divided-chamber system provides a powerful experimental approach to investigate the physiological mechanisms regulating nodal root growth responses to adverse soil conditions. Future studies may include measurements of hydraulic conductivity, anatomical characterization of vascular elements near the growth zone, aquaporin content and activity, and suberin deposition in response to low soil water potentials.

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Sink strength of citrus rootstocks under water deficit

Tree Physiology ◽

10.1093/treephys/tpab008 ◽

2021 ◽

Author(s):

Simone F da Silva ◽

Marcela T Miranda ◽

Vladimir E Costa ◽

Eduardo C Machado ◽

Rafael V Ribeiro

Keyword(s):

Plant Growth ◽

Root Growth ◽

Water Deficit ◽

Carbon Allocation ◽

Sink Strength ◽

Rangpur Lime ◽

Carbon Supply ◽

Valencia Orange ◽

Source Sink ◽

Orange Trees

Abstract Carbon allocation between source and sink organs determines plant growth and is influenced by environmental conditions. Under water deficit, plant growth is inhibited before photosynthesis and shoot growth tends to be more sensitive than root growth. However, the modulation of source-sink relationship by rootstocks remain unsolved in citrus trees under water deficit. Citrus plants grafted on Rangpur lime are drought tolerant, which may be related to a fine coordination of the source-sink relationship for maintaining root growth. Here, we followed 13C allocation and evaluated physiological responses and growth of Valencia orange trees grafted on three citrus rootstocks (Rangpur lime, Swingle citrumelo and Sunki mandarin) under water deficit. As compared to plants on Swingle and Sunki rootstocks, ones grafted on Rangpur lime showed higher stomatal sensitivity to the initial variation of water availability and less accumulation of non-structural carbohydrates in roots under water deficit. High 13C allocation found in Rangpur lime roots indicates this rootstock has high sink demand associated with high root growth under water deficit. Our data suggest that Rangpur lime rootstock used photoassimilates as sources of energy and carbon skeletons for growing under drought, which is likely related to increases in root respiration. Taken together, our data revealed that carbon supply by leaves and delivery to roots are critical for maintaining root growth and improving drought tolerance, with citrus rootstocks showing differential sink strength under water deficit.

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Effect of earthworms on mycorrhization, root morphology and biomass of silver fir seedlings inoculated with black summer truffle (Tuber aestivum Vittad.)

Scientific Reports ◽

10.1038/s41598-021-85497-8 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Tina Unuk Nahberger ◽

Gian Maria Niccolò Benucci ◽

Hojka Kraigher ◽

Tine Grebenc

Keyword(s):

Root System ◽

Root Biomass ◽

Fine Root ◽

Abies Alba ◽

Fine Root Biomass ◽

Root Tip ◽

Silver Fir ◽

Tuber Aestivum ◽

Root Tips ◽

Root Parameters

AbstractSpecies of the genus Tuber have gained a lot of attention in recent decades due to their aromatic hypogenous fruitbodies, which can bring high prices on the market. The tendency in truffle production is to infect oak, hazel, beech, etc. in greenhouse conditions. We aimed to show whether silver fir (Abies alba Mill.) can be an appropriate host partner for commercial mycorrhization with truffles, and how earthworms in the inoculation substrate would affect the mycorrhization dynamics. Silver fir seedlings inoculated with Tuber. aestivum were analyzed for root system parameters and mycorrhization, how earthworms affect the bare root system, and if mycorrhization parameters change when earthworms are added to the inoculation substrate. Seedlings were analyzed 6 and 12 months after spore inoculation. Mycorrhization with or without earthworms revealed contrasting effects on fine root biomass and morphology of silver fir seedlings. Only a few of the assessed fine root parameters showed statistically significant response, namely higher fine root biomass and fine root tip density in inoculated seedlings without earthworms 6 months after inoculation, lower fine root tip density when earthworms were added, the specific root tip density increased in inoculated seedlings without earthworms 12 months after inoculation, and general negative effect of earthworm on branching density. Silver fir was confirmed as a suitable host partner for commercial mycorrhization with truffles, with 6% and 35% mycorrhization 6 months after inoculation and between 36% and 55% mycorrhization 12 months after inoculation. The effect of earthworms on mycorrhization of silver fir with Tuber aestivum was positive only after 6 months of mycorrhization, while this effect disappeared and turned insignificantly negative after 12 months due to the secondary effect of grazing on ectomycorrhizal root tips.

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The Arabidopsis Root Tip (Phospho)Proteomes at Growth-Promoting versus Growth-Repressing Conditions Reveal Novel Root Growth Regulators

Cells ◽

10.3390/cells10071665 ◽

2021 ◽

Vol 10 (7) ◽

pp. 1665

Author(s):

Natalia Nikonorova ◽

Evan Murphy ◽

Cassio Flavio Fonseca de Lima ◽

Shanshuo Zhu ◽

Brigitte van de Cotte ◽

...

Keyword(s):

Cell Wall ◽

Root Growth ◽

Growth Regulators ◽

Growth Regulation ◽

Phosphorylation Site ◽

Primary Root ◽

Root Tip ◽

Arabidopsis Root ◽

Growth Promoting ◽

The Impact

Auxin plays a dual role in growth regulation and, depending on the tissue and concentration of the hormone, it can either promote or inhibit division and expansion processes in plants. Recent studies have revealed that, beyond transcriptional reprogramming, alternative auxin-controlled mechanisms regulate root growth. Here, we explored the impact of different concentrations of the synthetic auxin NAA that establish growth-promoting and -repressing conditions on the root tip proteome and phosphoproteome, generating a unique resource. From the phosphoproteome data, we pinpointed (novel) growth regulators, such as the RALF34-THE1 module. Our results, together with previously published studies, suggest that auxin, H+-ATPases, cell wall modifications and cell wall sensing receptor-like kinases are tightly embedded in a pathway regulating cell elongation. Furthermore, our study assigned a novel role to MKK2 as a regulator of primary root growth and a (potential) regulator of auxin biosynthesis and signalling, and suggests the importance of the MKK2 Thr31 phosphorylation site for growth regulation in the Arabidopsis root tip.

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Sewage sludge application enhances soil properties and rice growth in a salt-affected mudflat soil

Scientific Reports ◽

10.1038/s41598-020-80358-2 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Yuhua Shan ◽

Min Lv ◽

Wengang Zuo ◽

Zehui Tang ◽

Cheng Ding ◽

...

Keyword(s):

Sewage Sludge ◽

Organic Carbon ◽

Plant Growth ◽

Root Growth ◽

Soil Fertility ◽

Soil Properties ◽

Soluble Sugar ◽

Soil Reclamation ◽

Rice Growth ◽

Promote Plant Growth

AbstractThe most important measures for salt-affected mudflat soil reclamation are to reduce salinity and to increase soil organic carbon (OC) content and thus soil fertility. Salinity reduction is often accomplished through costly freshwater irrigation by special engineering measures. Whether fertility enhancement only through one-off application of a great amount of OC can improve soil properties and promote plant growth in salt-affected mudflat soil remains unclear. Therefore, the objective of our indoor pot experiment was to study the effects of OC amendment at 0, 0.5%, 1.0%, 1.5%, and 2.5%, calculated from carbon content, by one-off application of sewage sludge on soil properties, rice yield, and root growth in salt-affected mudflat soil under waterlogged conditions. The results showed that the application of sewage sludge promoted soil fertility by reducing soil pH and increasing content of OC, nitrogen and phosphorus in salt-affected mudflat soil, while soil electric conductivity (EC) increased with increasing sewage sludge (SS) application rates under waterlogged conditions. In this study, the rice growth was not inhibited by the highest EC of 4.43 dS m−1 even at high doses of SS application. The SS application increased yield of rice, promoted root growth, enhanced root activity and root flux activity, and increased the soluble sugar and amino acid content in the bleeding sap of rice plants at the tillering, jointing, and maturity stages. In conclusion, fertility enhancement through organic carbon amendment can “offset” the adverse effects of increased salinity and promote plant growth in salt-affected mudflat soil under waterlogged conditions.

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