Plant root and rhizosphere
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Rescooped by Vasta Hsu from Plant Biology Teaching Resources (Higher Education)
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Plant Physiology, Focus Issue on Roots, October 2014

Plant Physiology, Focus Issue on Roots, October 2014 | Plant root and rhizosphere | Scoop.it

"The nature of roots is to bury themselves into the soil and to enter into most intimate contact with their substrate, such that it is very hard to observe their growth and development, much less to extract them from the soil intact. Moreover, the soil is a substrate of mind-boggling heterogeneity and complexity, its complicated chemical and physical structure being potentiated by the biological diversity in the form of microbial communities. "


Via Mary Williams
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An auxin-responsive endogenous peptide regulates root development in Arabidopsis - Yang - Journal of Integrative Plant Biology -

An auxin-responsive endogenous peptide regulates root development in Arabidopsis - Yang - Journal of Integrative Plant Biology - | Plant root and rhizosphere | Scoop.it

Auxin plays critical roles in root formation and development. The components involved in this process, however, are not well understood. Here, we newly identified a peptide encoding gene, AREP1 (Auxin Responsive Endogenous Polypeptide 1), which is induced by auxin, and mediates root development in Arabidopsis. Expression of AREP1 was specific to the cotyledon and to root and shoot meristem tissues. Amounts of AREP1 transcripts and AREP1-GFP fusion proteins were elevated in response to IAA treatment. Suppression of AREP1 through RNAi silencing resulted in reduction of primary root length, increase of lateral root number, and expansion of adventitious roots, compared to the observations in wild-type plants in the presence of auxin. By contrast, transgenic plants over-expressing AREP1 showed enhanced growth of the primary root under auxin treatment. Additionally, root morphology, including lateral root number and adventitious roots, differed greatly between transgenic and wild-type plants. Further analysis indicated that the expression of auxin-responsive genes, such as IAA3, IAA7, IAA17, GH3.2, GH3.3, and SAUR-AC1, was significantly higher in AREP1 RNAi plants, and was slightly lower in AREP1 overexpressing plants than in wild-type plants. These results suggest that the novel endogenous peptide AREP1 plays an important role in the process of auxin-mediated root development.


Via Christophe Jacquet
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The key players of the primary root growth and development also function in lateral roots in Arabidopsis - Springer

The key players of the primary root growth and development also function in lateral roots in Arabidopsis - Springer | Plant root and rhizosphere | Scoop.it

Key message

The core regulators which are required for primary root growth and development also function in lateral root development or lateral root stem cell niche maintenance.

Abstract

The primary root systems and the lateral root systems are the two important root systems which are vital to the survival of plants. Though the molecular mechanism of the growth and development of both the primary root systems and the lateral root systems have been extensively studied individually in Arabidopsis, there are not so much evidence to show that if both root systems share common regulatory mechanisms. AP2 family transcription factors such as PLT1 (PLETHORA1) and PLT2, GRAS family transcription factors such as SCR (SCARECROW) and SHR (SHORT ROOT) and WUSCHEL-RELATED HOMEOBOX transcription factor WOX5 have been extensively studied and found to be essential for primary root growth and development. In this study, through the expression pattern analysis and mutant examinations, we found that these core regulators also function in lateral root development or lateral root stem cell niche maintenance.


Via Christophe Jacquet
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Do root hydraulic properties change during the early vegetative stage of plant development in barley (Hordeum vulgare)?

Do root hydraulic properties change during the early vegetative stage of plant development in barley (Hordeum vulgare)? | Plant root and rhizosphere | Scoop.it

Background and Aims As annual crops develop, transpirational water loss increases substantially. This increase has to be matched by an increase in water uptake through the root system. The aim of this study was to assess the contributions of changes in intrinsic root hydraulic conductivity (Lp, water uptake per unit root surface area, driving force and time), driving force and root surface area to developmental increases in root water uptake.

Methods Hydroponically grown barley plants were analysed during four windows of their vegetative stage of development, when they were 9–13, 14–18, 19–23 and 24–28 d old. Hydraulic conductivity was determined for individual roots (Lp) and for entire root systems (Lpr). Osmotic Lp of individual seminal and adventitious roots and osmotic Lpr of the root system were determined in exudation experiments. Hydrostatic Lp of individual roots was determined by root pressure probe analyses, and hydrostatic Lpr of the root system was derived from analyses of transpiring plants.

Key Results Although osmotic and hydrostatic Lp and Lpr values increased initially during development and were correlated positively with plant transpiration rate, their overall developmental increases (about 2-fold) were small compared with increases in transpirational water loss and root surface area (about 10- to 40-fold). The water potential gradient driving water uptake in transpiring plants more than doubled during development, and potentially contributed to the increases in plant water flow. Osmotic Lpr of entire root systems and hydrostatic Lpr of transpiring plants were similar, suggesting that the main radial transport path in roots was the cell-to-cell path at all developmental stages.

Conclusions Increase in the surface area of root system, and not changes in intrinsic root hydraulic properties, is the main means through which barley plants grown hydroponically sustain an increase in transpirational water loss during their vegetative development.

 

 


Via Christophe Jacquet
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Good dirt with good friends

Good dirt with good friends | Plant root and rhizosphere | Scoop.it
An analysis of data from forests across the planet reveals that the types of beneficial fungus with which tree roots associate determine the amount of carbon stored in soils. See Letter p.543

Via Jean-Michel Ané, Christophe Jacquet
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