scholarly journals PIN7 auxin carrier is a terminator of radial root expansion in Arabidopsis thaliana

2018 ◽  
Author(s):  
Michel Ruiz Rosquete ◽  
Jürgen Kleine-Vehn
Keyword(s):  
Radial Growth ◽  
Lateral Roots ◽  
Root Systems ◽  
Plateau Phase ◽  
Directional Growth ◽  
Auxin Signalling ◽  
Molecular Determinants ◽  
Auxin Carrier ◽  
Auxin Efflux Carriers ◽  
Bending Response

AbstractDirectional growth of lateral roots is critical for radial expansion and soil coverage. Despite its importance, almost nothing is known about its molecular determinants. Initially, young lateral roots (LRs) grow away from the parental root maintaining the angle acquired shortly after emergence. A second downwards bending response to gravity terminates the so-called plateau phase and thereby limits the radial root expansion. Here we show that the exit from the plateau phase correlates with an increase in auxin signalling at the tip of LRs. Moreover, the increase in auxin levels induces the termination of the plateau phase, which requires PIN auxin efflux carriers. Our data suggests that the developmental increase of auxin triggers the preferential de-repression of PIN7 in gravity-sensing columella cells. The subsequent polarization of PIN7 heralds the bending towards gravity and, hence, the exit from the plateau phase. This developmental framework reveals the distinct roles of PIN auxin efflux carriers in controlling the radial growth of root systems.

scholarly journals A Positive Tropism of Rice Roots toward a Nutrient Source

2019 ◽  
Vol 61 (3) ◽  
pp. 546-553
Author(s):  
Kiyoshi Yamazaki ◽  
Yoshihiro Ohmori ◽  
Toru Fujiwara
Keyword(s):  
Cell Elongation ◽  
Lateral Roots ◽  
Fourth Power ◽  
Nutrient Concentrations ◽  
Root Tips ◽  
High Moisture ◽  
Nutrient Source ◽  
Directional Growth ◽  
Rice Roots ◽  
Differential Cell

Abstract Plants take up water and nutrients through roots, and uptake efficiency depends on root behavior. Roots recognize the moisture gradient in the soil and grow toward the direction of high moisture. This phenomenon is called hydrotropism, and it contributes to efficient water uptake. As nutrients in soil are also unevenly distributed, it is beneficial for plants to grow their roots in the direction of increasing nutrient concentrations, but such a phenomenon has not been demonstrated. Here, we describe the directional growth of roots in response to a nutrient gradient. Using our assay system, the gradient of a nitrogen nutrient, NH4+, was sufficient to stimulate positive tropic responses of rice lateral roots. This phenomenon is a tropism of plant roots to nutrients; hence, we propose the name ‘nutritropism’. As well as other tropisms, differential cell elongation was observed before the elongation zone during nutritropism, but the pattern promoting cell elongation preferentially on the non-stimulated side was opposite to those in root hydrotropism and gravitropism. Our evaluation of the NH4+ gradient suggested that the root tips responded to a sub-micromolar difference in NH4+ concentration on both sides of the root. Hydrotropism, gravitropism and phototropism were described in plants as the ‘power of movement’ by Charles and Francis Darwin in 1880, and these three tropisms have attracted the attention of plant scientists for more than 130 years. Our discovery of nutritropism represents the fourth ‘power of movement’ in plants and provides a novel root behavioral property used by plants to acquire nutrients efficiently.

scholarly journals Root biomass of beech as a factor influencing the wind tree stability 

2019 ◽  
Vol 48 (No. 12) ◽  
pp. 549-564 ◽  
Author(s):  
J. Kodrík ◽  
M. Kodrík
Keyword(s):  
Root System ◽  
Groundwater Level ◽  
Negative Impact ◽  
Lateral Roots ◽  
Root Systems ◽  
Static Stability ◽  
Soil Conditions ◽  
Tree Stability ◽  
Ground Biomass ◽  
Below Ground

Beech is, thanks to its root system, in general considered to be a wind-resistant woody plant species. Nevertheless, the research on beech root systems has revealed that it is not possible to mechanically divide the woody plants into deep rooted and shallow rooted, because their root systems are modified according to various stand conditions. The root system shape, growth and development are mostly influenced by soil conditions and groundwater level. In the case of a high groundwater level beech root systems do not form tap roots and the lateral roots are rather thin and weak. Important factor for the tree static stability is number of roots with diameter 3–10 cm. The most important for the tree stability are roots with diameter over 10 cm. Wood-destroying fungi have strong negative impact on tree static stability. There are differences between beech below-ground biomass growing in soils rich in nutrients and poor in nutrients. The total below-ground biomass of the beech stands poor in nutrients is higher.

Lateral Root Pruning of Sitka Spruce and Western Hemlock Seedlings

1972 ◽  
Vol 2 (3) ◽  
pp. 223-227 ◽  
Author(s):  
S. Eis ◽  
J. R. Long
Keyword(s):  
Lateral Root ◽  
Lateral Roots ◽  
Root Systems ◽  
Growing Season ◽  
Sitka Spruce ◽  
Picea Sitchensis ◽  
Short Length ◽  
Western Hemlock ◽  
Root Pruning

Roots of Sitka spruce (Picea sitchensis) and western hemlock (Tsugaheterophylla) seedlings were side pruned in nursery beds at semimonthly intervals to produce dense and compact root systems. Root pruning early in the growing season stimulated the growth of existing roots and also initiated new roots. The densest root systems were produced by pruning before the end of June. However, because of the short length of lateral roots on seedlings early in their second growing season, pruning equidistant between rows 18 cm apart was ineffective. The best compromise appeared to be to prune spruce at the beginning of July, and hemlock around the middle of July. Earlier pruning equidistant between rows can be effective on larger seedlings during their third growing season. If early pruning is carried out on 2 + 0 seedlings, a pruning distance of about 6 cm from the row is recommended.

Modeling in-situ pine root decomposition using data from a 60-year chronosequence

2002 ◽  
Vol 32 (9) ◽  
pp. 1675-1684 ◽  
Author(s):  
Kim H Ludovici ◽  
Stanley J Zarnoch ◽  
Daniel D Richter
Keyword(s):  
Loblolly Pine ◽  
Lateral Root ◽  
Lateral Roots ◽  
Nutrient Release ◽  
Root Systems ◽  
Root Decomposition ◽  
Good Precision ◽  
Clear Cut ◽  
Stump Diameter

Because the root system of a mature pine tree typically accounts for 20–30% of the total tree biomass, decomposition of large lateral roots and taproots following forest harvest and re-establishment potentially impact nutrient supply and carbon sequestration in pine systems over several decades. If the relationship between stump diameter and decomposition of taproot and lateral root material, i.e., wood and bark, can be quantified, a better understanding of rates and patterns of sequestration and nutrient release can also be developed. This study estimated decomposition rates from in-situ root systems using a chronosequence approach. Nine stands of 55- to 70-year-old loblolly pine (Pinus taeda L.) that had been clear-cut 0, 5, 10, 20, 25, 35, 45, 55, and 60 years ago were identified on well-drained Piedmont soils. Taproot and lateral root systems were excavated, measured, and weighed. Although more than 50% of the total root mass decomposed during the first 10 years after harvest, field excavations recovered portions of large lateral roots (>5 cm diameter) and taproots that persisted for more than 35 and 60 years, respectively. Results indicate that decomposition of total root biomass, and its component parts, from mature, clear-cut loblolly pine stands, can be modeled with good precision as a function of groundline stump diameter and years since harvest.

THE LENGTH, TANGENTIAL DIAMETER, AND LENGTH/WIDTH RATIO OF CONIFER TRACHEIDS

1965 ◽  
Vol 43 (8) ◽  
pp. 967-984 ◽  
Author(s):  
M. W. Bannan
Keyword(s):  
Radial Growth ◽  
Lateral Roots ◽  
Height Growth ◽  
Growth Potential ◽  
Cell Length ◽  
Small Cells ◽  
Width Ratio ◽  
Mature Trees ◽  
Cell Dimensions ◽  
Length Width

In the gradual enlargement of tracheid dimensions which takes place outward from the pith in the stem and branches, growth in cell length outstrips that in tangential width so that the length/width ratio rises. Largest tracheids are usually found in the inner wood of lateral roots, where the length/width ratio is highest. Interspecific and interregional differences follow a similar pattern of relationship with respect to cell dimensions. As a rule, species or races which inhabit unfavorable sites have comparatively small cells with a low length/width ratio. Species which populate better sites and have greater growth potential are characterized by longer cells and a higher length/width ratio. Indications exist of a positive relationship between height growth, tracheid length, and the length/width ratio. On the other hand, increased radial growth in mature trees is accompanied by reduction in mean cell length and a lowering of the length/width ratio.

scholarly journals The impact of morphometric characteristics of plants self-pollinated sunflower lines on its lodging

2020 ◽  
Vol 4 (184) ◽  
pp. 3-11
Author(s):  
B.N. Bochkaryov ◽  
◽  
N.V. Medvedeva ◽  
E.N. Ryzhenko ◽  
◽  
...  
Keyword(s):  
Root System ◽  
Lateral Roots ◽  
Root Systems ◽  
Morphometric Characteristics ◽  
Main Root ◽  
Lodging Resistance ◽  
Oil Crops ◽  
Russian Research Institute ◽  
Top Soil ◽  
The Impact

We carried out the research in 2018-2019 at the experimental station of V.S. Pustovoit All-Russian Research Institute of Oil Crops. The aim of the research is to study the effect of certain morphometric characteristics of the overground part of plants and the architectonics of the root system on the sunflower lodging. We found significant differences in the architectonics of root systems in 17 maternal lines of sunflower: we identified three morphotypes, differing in the number and thickness of lateral roots of the first and subsequent orders, located in the top soil. We identified the sunflower lines that have a root system with a well-developed main root and many lateral roots of various orders (type A), lines with a normally developed main root and a small number of lateral roots (type B), and lines with a poorly developed main root and few lateral roots in top soil (type C). We identified the presence of both low and high lodging in sunflower lines with different types of root systems. At the same time, there is a tendency towards higher lodging in lines with root system types B and C. The line SL12 3660 showed the maximum lodging resistance during two years of observations. It may be of interest for further work as a possible source of a lodging resistance trait.

scholarly journals Root type and soil phosphate determine the taxonomic landscape of colonizing fungi and the transcriptome of field-grown maize roots

2017 ◽  
Author(s):  
Peng Yu ◽  
Chao Wang ◽  
Jutta A. Baldauf ◽  
Huanhuan Tai ◽  
Caroline Gutjahr ◽  
...  
Keyword(s):  
Community Composition ◽  
Sequence Data ◽  
Lateral Roots ◽  
Root Systems ◽  
Fungal Communities ◽  
List Type ◽  
Transcriptomic Response ◽  
Soil Phosphate ◽  
Microscopic Evaluation ◽  
Root Types

Key findingOur data illustrates for the first time that root type identity and phosphate availability determine the community composition of colonizing fungi and shape the transcriptomic response of the maize root system.SummaryPlant root systems consist of different root types colonized by a myriad of soil microorganisms including fungi, which influence plant health and performance. The distinct functional and metabolic characteristics of these root types may influence root type inhabiting fungal communities.We performed internal transcribed spacer (ITS) DNA profiling to determine the composition of fungal communities in field-grown axial and lateral roots of maize (Zea mays L.) and in response to two different soil phosphate (P) regimes. In parallel, these root types were subjected to transcriptome profiling by RNA-Seq.We demonstrated that fungal communities were influenced by soil P levels in a root type-specific manner. Moreover, maize transcriptome sequencing revealed root type-specific shifts in cell wall metabolism and defense gene expression in response to high phosphate. Furthermore, lateral roots specifically accumulated defense related transcripts at high P levels. This observation was correlated with a shift in fungal community composition including a reduction of colonization by arbuscular mycorrhiza fungi as observed in ITS sequence data and microscopic evaluation of root colonization.Our findings point towards a diversity of functional niches within root systems, which dynamically change in response to soil nutrients. Our study provides new insights for understanding root-microbiota interactions of individual root types to environmental stimuli aiming to improve plant growth and fitness.

scholarly journals The root system of the husk tomato (Physalis ixocarpa Brot.)

2013 ◽  
Vol 39 (2) ◽  
pp. 367-383
Author(s):  
Juan Mulato Brito ◽  
Leszek S. Jankiewicz ◽  
Victor M. Fernández Orduňa ◽  
Francisco Cartujano Escobar
Keyword(s):  
Root System ◽  
Quantitative Estimation ◽  
Lateral Roots ◽  
Soil Layer ◽  
Root Systems ◽  
Dry Mass ◽  
Central Axis ◽  
Temperate Climate ◽  
Small Roots ◽  
Husk Tomato

The husk tomato (<i>Physalis ixocarpa</i> Brot.) is widely cultivated in central Mexico, and may be grown in countries with a temperate climate. The experiment was set up during the dry period of the year (average weekly temperature 17-22°C) in the State of Morelos, Mexico, using the cv. 'Rendidora' in loamy clay soil and furrow irrigation. The roots were investigated by the pinboard method modified by Garcia Blancas and Grajeda Gómez (in print), partly adapted by us for quantitative estimation of root systems. Two plants were investigated every second week. They had a well developed tap root. Most of their lateral roots were found in the superficial soil layer, 0-20 cm. The root dry mass was also concentrated near the central axis of the plant. The majority of root apices were, however, found in the soil cylinders 10-40 em from the central axis. During the senescence of the aerial part (14th week after emergence) the root system lost a large part of its small roots. The modification of the pinboard method, by Garcia Blancas and Grajeda Gómez (in print) permited us investigating the root systems with very simple tools, in situ.

Changes in loblolly pine root growth potential from September to April

1987 ◽  
Vol 17 (7) ◽  
pp. 635-643 ◽  
Author(s):  
Laura E. DeWald ◽  
Peter P. Feret
Keyword(s):  
Root Growth ◽  
Loblolly Pine ◽  
Environmental Changes ◽  
Lateral Roots ◽  
Root Systems ◽  
Shoot Elongation ◽  
Growth Potential ◽  
Late Winter ◽  
Root Growth Potential ◽  
Shoot Phenology

Loblolly pine (Pinustaeda L.) 1 + 0 seedlings were periodically hand lifted from a Virginia nursery to determine how root growth potential (RGP) varied between September and April. Several seedling characteristics, RGP, and shoot phenology were recorded for each lift date in 1983–1984 and 1984–1985. An attempt was made to relate RGP variation to changes in the nursery environment and to shoot phenology. Root growth potential variation was consistent between years and was more closely related to shoot phenological changes than to short-term environmental changes. During the development of dormancy, RGP was low, RGP increased when shoot activity resumed during the RGP tests (late winter, early spring), and declined as active shoot elongation began in the nursery. When RGP was low, elongation of existing lateral roots primarily contributed to the new root systems, but as seedling metabolism increased in the late winter, new root initiation also contributed to new root systems. Absolute differences in RGP between years may be related to the fibrosity of seedling root systems.

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