Roots – the hidden provider | Frontiers Research Topic

Editorial

13 June 2017

Editorial: Roots—The Hidden Provider

Janin Riedelsberger

and

Michael R. Blatt

5,869 views

12 citations

Editors

Janin Riedelsberger

University of Talca

Mike Blatt

University of Glasgow

Impact

Heat map analysis summarizing the plant responses to nitrogen nutrition and salinity. Results were calculated as Logarithm base 2 (Log2) of salt stressed values/control values (S/C) or high nitrogen/low nitrogen (HN/LN) for all the treatments, LN, HN, and HNsplit (LNR, HNR, and HNSR). Results were visualized using a false color scale, with blue indicating an increase and red a decrease of values relative to those in control condition. No differences were visualized by white squares.

Original Research

09 January 2017

Durum Wheat Roots Adapt to Salinity Remodeling the Cellular Content of Nitrogen Metabolites and Sucrose

Maria Grazia Annunziata

, 4 more and

Petronia Carillo

8,660 views

144 citations

Iron mobilization from an scarcely soluble Fe(III)-oxide as affected by coumarins. (A) Structure-activity relationship of coumarins on Fe mobilization activity. The assays consisted in the incubation of 10 mg of Fe(III)-oxide with a solution of 0 (blank) or 100 μM of the indicated coumarins and 600 μM BPDS at two different pH values, 5.5 and 7.5. Total Fe and Fe(II)-(BPDS)3 in solution were determined by ICP-MS and spectrophotometry, respectively. (B) Effects of the fraxetin concentration on the Fe mobilization activity at pH 7.5. Scatter plot of the concentration of fraxetin vs. the total Fe mobilized and the Fe(II), with linear regression lines in black and their corresponding equations. In all cases (A,B), data are means ± SE (n = 3–12) and asterisks denote a statistically significant difference between blank and a coumarin-containing assay medium as determined by Student’s t- test (p < 0.05).

Original Research

23 November 2016

Accumulation and Secretion of Coumarinolignans and other Coumarins in Arabidopsis thaliana Roots in Response to Iron Deficiency at High pH

Patricia Sisó-Terraza

, 6 more and

Ana Álvarez-Fernández

11,245 views

101 citations

Effects of rootstocks on the nutrient concentration and growth/yield of grafted plants.

Review

21 October 2016

Grafting: A Technique to Modify Ion Accumulation in Horticultural Crops

Muhammad A. Nawaz

, 5 more and

Zhilong Bie

28,913 views

165 citations

Review

04 October 2016

The ALMT Family of Organic Acid Transporters in Plants and Their Involvement in Detoxification and Nutrient Security

Tripti Sharma

, 2 more and

Miguel A. Piñeros

Evolutionary relationship of ALMTs from Arabidopsis thaliana, Oryza sativa and Vitis vinifera. ALMTs of higher plants segregate into five different clades. Figure adapted from Dreyer et al. (2012). Nomenclature of ALMTs from V. vinifera according to De Angeli et al. (2013a). For better illustration, only TaALMT1 from Triticum aestivum was included in the tree as an example for functionally characterized ALMTs from species different from A. thaliana, O. sativa, and V. vinifera. ZmALMT1, ZmALMT2, HvALMT1, ScALMT1, and HlALMT1 cluster with TaALMT1 and OsALMT1 in clade 1; BnALMT1 and BnALMT2 cluster with AtALMT1 in clade 1; GmALMT1 clusters with AtALMT8 and VvALMT8 in clade 1; and MdMA1 clusters with AtALMT4, AtALMT5, AtALMT6, and VvALMT6 in clade 2.

About a decade ago, members of a new protein family of anion channels were discovered on the basis of their ability to confer on plants the tolerance toward toxic aluminum ions in the soil. The efflux of Al³⁺-chelating malate anions through these channels is stimulated by external Al³⁺ ions. This feature of a few proteins determined the name of the entire protein family as Aluminum-activated Malate Transporters (ALMT). Meanwhile, after several years of research, it is known that the physiological roles of ALMTs go far beyond Al-detoxification. In this review article we summarize the current knowledge on this transporter family and assess their involvement in diverse physiological processes.

15,464 views

130 citations

Schematic representation of low- (light gray dots) and high- (dark gray dots) affinity nitrate transporters expressed in Arabidopsis root. Three stages of root developement have been represented according to Birnbaum et al. (2003).

Mini Review

21 September 2016

Transporters Involved in Root Nitrate Uptake and Sensing by Arabidopsis

Mélanie Noguero

and

Benoît Lacombe

12,815 views

88 citations

Review

31 August 2016

Roots Withstanding their Environment: Exploiting Root System Architecture Responses to Abiotic Stress to Improve Crop Tolerance

Iko T. Koevoets

, 2 more and

Christa Testerink

Schematic overview of the effect of root-zone temperature on plant performance and underlying general changes in RSA (brown). To broaden the temperature range for optimal plant performance (yellow), plants should invest in lateral root formation (suboptimal temperature range) and/or axile root length (supraoptimal temperature range). The adaptive value of these RSA changes are, respectively, an increased root surface area to improve resource uptake capacity and drought adaptation by penetration to lower soil layers.

To face future challenges in crop production dictated by global climate changes, breeders and plant researchers collaborate to develop productive crops that are able to withstand a wide range of biotic and abiotic stresses. However, crop selection is often focused on shoot performance alone, as observation of root properties is more complex and asks for artificial and extensive phenotyping platforms. In addition, most root research focuses on development, while a direct link to the functionality of plasticity in root development for tolerance is often lacking. In this paper we review the currently known root system architecture (RSA) responses in Arabidopsis and a number of crop species to a range of abiotic stresses, including nutrient limitation, drought, salinity, flooding, and extreme temperatures. For each of these stresses, the key molecular and cellular mechanisms underlying the RSA response are highlighted. To explore the relevance for crop selection, we especially review and discuss studies linking root architectural responses to stress tolerance. This will provide a first step toward understanding the relevance of adaptive root development for a plant’s response to its environment. We suggest that functional evidence on the role of root plasticity will support breeders in their efforts to include root properties in their current selection pipeline for abiotic stress tolerance, aimed to improve the robustness of crops.

32,508 views

426 citations

Effect of sid2 mutation on bik1-mediated resistance against P. brassicae. (A) Mature shoot phenotypes of wild type and mutant plants. The top of the picture shows uninoculated plants, while the bottom shows plants inoculated with P. brassicae. (B) Real-time PCR analysis was performed to assess the expression levels of P. brassicae at 28 days after inoculation with P. brassicae. (C) Phytopathological analysis of wild type and mutant plants. The percentages of plants in the individual disease classes are shown. 0, no symptoms; 1, very small galls mainly on lateral roots and that do not impair the main root; 2, small galls covering the main root and few lateral roots; 3, medium to large galls, also including the main root; and 4, severe galls on lateral root, main root or rosette; fine roots completely destroyed. For each treatment, 26–30 Arabidopsis plants were analyzed. The qualitative disease assessment data were initially analyzed using spss and subsequently further analyzed after comparing the mean rank differences. The asterisk indicates a significant difference at P < 0.01. The disease index for each sample is shown as a number above the respective histograms. (D) Images of the shoots without inoculation are shown in (A). (E) Clubroot symptoms in plants. Images of the shoots with inoculation are shown in (A).

Original Research

13 September 2016

Arabidopsis Mutant bik1 Exhibits Strong Resistance to Plasmodiophora brassicae

Tao Chen

, 7 more and

Daohong Jiang

6,209 views

36 citations

Review

29 August 2016

Calcium-Mediated Abiotic Stress Signaling in Roots

Katie A. Wilkins

, 2 more and

Julia M. Davies

Roots are subjected to a range of abiotic stresses as they forage for water and nutrients. Cytosolic free calcium is a common second messenger in the signaling of abiotic stress. In addition, roots take up calcium both as a nutrient and to stimulate exocytosis in growth. For calcium to fulfill its multiple roles must require strict spatio-temporal regulation of its uptake and efflux across the plasma membrane, its buffering in the cytosol and its sequestration or release from internal stores. This prompts the question of how specificity of signaling output can be achieved against the background of calcium’s other uses. Threats to agriculture such as salinity, water availability and hypoxia are signaled through calcium. Nutrient deficiency is also emerging as a stress that is signaled through cytosolic free calcium, with progress in potassium, nitrate and boron deficiency signaling now being made. Heavy metals have the capacity to trigger or modulate root calcium signaling depending on their dose and their capacity to catalyze production of hydroxyl radicals. Mechanical stress and cold stress can both trigger an increase in root cytosolic free calcium, with the possibility of membrane deformation playing a part in initiating the calcium signal. This review addresses progress in identifying the calcium transporting proteins (particularly channels such as annexins and cyclic nucleotide-gated channels) that effect stress-induced calcium increases in roots and explores links to reactive oxygen species, lipid signaling, and the unfolded protein response.

13,903 views

164 citations