Enhanced root growth of the brb (bald root barley) mutant in drying soil allows similar shoot physiological responses to soil water deficit as wild-type plants

2016 ◽  
Vol 43 (2) ◽  
pp. 199 ◽  
Author(s):  
Ian C. Dodd ◽  
Eugene Diatloff
Keyword(s):  
Water Deficit ◽  
Plant Root ◽  
Physiological Responses ◽  
Root Hairs ◽  
Root Surface ◽  
Root Surface Area ◽  
Genotypic Differences ◽  
Wild Type ◽  
Leaf Elongation ◽  
Hordeum Vulgare L

The genetics, molecular biology and nutrient uptake of plant root hair mutants have been studied in detail, but their physiological responses to soil drying have not. Thus, the root hairless brb (bald root barley) barley (Hordeum vulgare L.) mutant and its wild type (WT) were grown in drying soil. Well-watered, pre-tillering plants showed no genotypic differences in daily transpiration and leaf elongation rate, and the ratio of day to night leaf elongation (D/N, a sensitive indicator of water stress). After withholding water for 25 days, root hydraulic conductivity and xylem ABA concentration were similar between genotypes, but WT plants had more tillers and D/N was more than halved in brb. To avoid possible developmental and nutritional differences confounding responses to water deficit, pre-tillering plants were allowed to dry soils of high and low phosphorus (P) status. Although leaf area, leaf water potential and shoot fresh weight (FW) were similar in the two genotypes, root FW of brb was greater by 44 and 18% in a high and low P soil respectively. This adaptive response allowed brb to maintain similar shoot growth and transpiration as WT plants, despite decreased effective root surface area in the absence of root hairs.

scholarly journals Root hair specification and its growth in response to nutrients

2021 ◽  
Vol 49 (2) ◽  
pp. 12258
Author(s):  
Xian HUANG ◽  
Tianzhi GONG ◽  
Mei LI ◽  
Cenghong HU ◽  
Dejian ZHANG ◽  
...  
Keyword(s):  
Root Hair ◽  
Reverse Genetics ◽  
Current Knowledge ◽  
Plant Root ◽  
Root Hairs ◽  
Root Surface ◽  
Root Surface Area ◽  
Root Hair Development ◽  
Hair Development ◽  
Calcium Iron

Plant root hairs are cylindrical tubular projections from root epidermal cells. They increase the root surface area, which is important for the acquisition of water and nutrients, microbe interactions, and plant anchorage. The root hair specification, the effect of root hairs on nutrient acquisition and the mechanisms of nutrients (calcium, iron, magnesium, nitrogen, phosphorus, and potassium) that affect root hair development and growth were reviewed. The gene regulatory network on root hair specification in the plant kingdom was highlighted. More work is needed to clone the genes of additional root hair mutants and elucidate their roles, as well as undertaking reverse genetics and mutant complementation studies to add to the current knowledge of the signaling networks, which are involved in root hair development and growth regulated by nutrients.

scholarly journals Hypothetical Protein Avin_16040 as the S-Layer Protein of Azotobacter vinelandii and Its Involvement in Plant Root Surface Attachment

2015 ◽  
Vol 81 (21) ◽  
pp. 7484-7495 ◽  
Author(s):  
Pauline Woan Ying Liew ◽  
Bor Chyan Jong ◽  
Nazalan Najimudin
Keyword(s):  
Cell Surface ◽  
Deletion Mutant ◽  
Azotobacter Vinelandii ◽  
Plant Root ◽  
Hypothetical Protein ◽  
Surface Hydrophobicity ◽  
Root Surface ◽  
Bacterial Cells ◽  
Wild Type ◽  
Content Type

ABSTRACTA proteomic analysis of a soil-dwelling, plant growth-promotingAzotobacter vinelandiistrain showed the presence of a protein encoded by the hypotheticalAvin_16040gene when the bacterial cells were attached to theOryza sativaroot surface. AnAvin_16040deletion mutant demonstrated reduced cellular adherence to the root surface, surface hydrophobicity, and biofilm formation compared to those of the wild type. By atomic force microscopy (AFM) analysis of the cell surface topography, the deletion mutant displayed a cell surface architectural pattern that was different from that of the wild type.Escherichia colitransformed with the wild-typeAvin_16040gene displayed on its cell surface organized motifs which looked like the S-layer monomers ofA. vinelandii. The recombinantE. colialso demonstrated enhanced adhesion to the root surface.

The effect of root hairs under drought in open field conditions

2021 ◽  
Author(s):  
Maria Marin ◽  
Deborah S Feeney ◽  
Lawrie K Brown ◽  
Muhammad Naveed ◽  
Siul Ruiz ◽  
...  
Keyword(s):  
Water Potential ◽  
Water Deficit ◽  
Open Field ◽  
Leaf Water Potential ◽  
Root Hair ◽  
Root Hairs ◽  
Leaf Water ◽  
Plant Water ◽  
Clay Loam ◽  
Wild Type

<p>Root hairs represent an attractive target for future crop breeding, to improve resource use efficiency and stress tolerance. Most studies investigating root hairs have focused on plant tolerance to phosphorus deficiency and rhizosheath formation under controlled conditions. However, data on the interplay between root hairs and open-field systems, under contrasting soils and climate conditions, are limited. Although root hairs and rhizosphere are assumed to play a key role in regulating plant water relations, their effect on plant water uptake has been rarely investigated. As such, this study aimed to experimentally elucidate some of the impacts that root hairs have on plant performance under field conditions and water deficit. A field experiment was set up in Scotland for two consecutive years, in 2017 (a typical year) and 2018 (the driest growing season ever recorded at this site), under different soil textures (i.e., clay loam vs. sandy loam). Five barley (Hordeum vulgare) genotypes exhibiting variation in root hair length and density were used in the study. Measurements of root hair density, length and its correlation with rhizosheath weight highlighted trait robustness in the field under variable environmental conditions. Root hairs did not confer a notable advantage to barley under optimal conditions, but under soil water deficit root hairs enhanced plant water status and stress tolerance. This resulted in less negative leaf water potential and lower leaf abscisic acid concentration, while promoting shoot phosphorus accumulation. Specifically, minimum leaf water potential differed significantly (P = 0.021) between the wild type (-1.43 MPa) and its hairless mutant (-1.76 MPa) grown in clay loam, with the mutant exhibiting greater water stress. In agreement with leaf water potential measurements, at the peak of water stress, leaf abscisic acid concentration was significantly (P = 0.023) greater for the hairless mutant (394 ng g<sup>-1</sup>) than the wild type (250 ng g<sup>-1</sup>) grown in clay loam soil. Under water deficit conditions, in clay loam soil, shoot phosphorus accumulation in the wild type (2.49 mg P shoot<sup>-1</sup>) was over twice that in the hairless mutant (1.10 mg P shoot<sup>-1</sup>). Furthermore, the presence of root hairs did not decrease yield under optimal conditions, while root hairs enhanced yield stability under drought. While yield of the hairless mutant significantly (P = 0.012) decreased from 2017 to 2018 in both clay (-26%) and sandy (-33%) loam soils, no significant differences were found between years in the yield of the wild type. Therefore, selecting for beneficial root hair traits can enhance yield stability without diminishing yield potential, overcoming the breeder’s dilemma of trying to simultaneously enhance both productivity and resilience. To our knowledge, the present findings provide the first evidence of the effect of root hairs under drought in open field conditions (i.e., real agricultural system). Therefore, along with the well-recognized role for P uptake, maintenance or enhancement of root hairs can represent a key trait for breeding the next generation of crops for improved drought tolerance in relation to climate change.</p>

Physiological and morphological aspects of interactions between Rhizobium meliloti and alfalfa (Medicago sativa) in association with Azospirillum brasilense

1993 ◽  
Vol 39 (6) ◽  
pp. 610-615 ◽  
Author(s):  
R. Itzigsohn ◽  
Y. Kapulnik ◽  
Y. Okon ◽  
A. Dovrat
Keyword(s):  
Medicago Sativa ◽  
Rhizobium Meliloti ◽  
Combined Treatment ◽  
Root Hairs ◽  
Background Level ◽  
Root Surface ◽  
Root Surface Area ◽  
Main Root ◽  
Nodule Number ◽  
Infection Threads

In a 50-L pot experiment with Medicago sativa grown under nonsterile conditions, a combined treatment of Azospirillum and Rhizobium was measured against soil inoculated with Rhizobium or Azospirillum alone or a control with a low background level of autochthonous rhizobia. The combined treatment significantly increased the shoot length and weight at 6 weeks and the regrowth shoot weight at 14 weeks when compared with the treatment with Rhizobium alone. In 1.5-L pots in which gnotobiotic conditions were maintained, the combined treatment led to more nodules on the main root at intermediate Rhizobium concentrations, and a greater root surface area at intermediate and high Rhizobium concentrations after 2 weeks but not after 4 weeks. In pouch-grown seedlings, plants were inoculated with either Rhizobium alone or in combination with Azospirillum or applied together with a flavonoid, luteolin (a nodulation gene inducer), or with a cytokinin, benzyl adenine. Luteolin had similar effects to those of Azospirillum in increasing the main root nodule number and the total nodule number. With Fahraeus slides, a significant increase was observed in the number of root hairs and the root diameter in the presence of Azospirillum as compared with the control and Rhizobium alone. There was no increase in the total number of infection threads; however, the combined treatment caused a significant decrease in the percentage of infected root hairs.Key words: Rhizobium, Azospirillum, Medicago, flavonoid, inoculation.

Genotypic water-deficit stress responses in durum wheat: association between physiological traits, microRNA regulatory modules and yield components

2017 ◽  
Vol 44 (5) ◽  
pp. 538 ◽  
Author(s):  
Haipei Liu ◽  
Amanda J. Able ◽  
Jason A. Able
Keyword(s):  
Durum Wheat ◽  
Stress Tolerance ◽  
Water Deficit ◽  
Stress Responses ◽  
Yield Components ◽  
Physiological Responses ◽  
Physiological Traits ◽  
Water Deficit Stress ◽  
Genotypic Differences ◽  
Time Points

In Mediterranean environments, water-deficit stress that occurs before anthesis significantly limits durum wheat (Triticum turgidum L. ssp. durum) production. Stress tolerant and stress sensitive durum varieties exhibit genotypic differences in their response to pre-anthesis water-deficit stress as reflected by yield performance, but our knowledge of the mechanisms underlying tolerance is limited. We have previously identified stress responsive durum microRNAs (miRNAs) that could contribute to water-deficit stress tolerance by mediating post-transcriptional silencing of genes that lead to stress adaptation (e.g. miR160 and its targets ARF8 (auxin response factor 8) and ARF18). However, the temporal regulation pattern of miR160-ARFs after induction of pre-anthesis water-deficit stress in sensitive and tolerant varieties remains unknown. Here, the physiological responses of four durum genotypes are described by chlorophyll content, leaf relative water content, and stomatal conductance at seven time-points during water-deficit stress from booting to anthesis. qPCR examination of miR160, ARF8 and ARF18 at these time-points revealed a complex stress responsive regulatory pattern, in the flag leaf and the head, subject to genotype. Harvest components and morphological traits measured at maturity confirmed the stress tolerance level of these four varieties for agronomic performance, and their potential association with the physiological responses. In general, the distinct regulatory pattern of miR160-ARFs among stress tolerant and sensitive durum varieties suggests that miRNA-mediated molecular pathways may contribute to the genotypic differences in the physiological traits, ultimately affecting yield components (e.g. the maintenance of harvest index and grain number).

scholarly journals Comparison of root tolerance to drought and aphid (Myzus persicae Sulzer) resistance among different potato (Solanum tuberosum L.) cultivars

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Peter Quandahor ◽  
Yuping Gou ◽  
Chunyan Lin ◽  
Jeffrey A. Coulter ◽  
Changzhong Liu
Keyword(s):  
Solanum Tuberosum ◽  
Root System ◽  
Surface Area ◽  
Water Deficit ◽  
Myzus Persicae ◽  
Root Surface ◽  
Root Surface Area ◽  
Root Tips ◽  
Projected Area ◽  
Aphid Infestation

AbstractThis study was conducted to determine the root system architecture and biochemical responses of three potato (Solanum tuberosum L.) cultivars to drought and aphid (Myzus persicae Sulzer) infestation under greenhouse conditions. A factorial experiment comprising three potato cultivars (Qingshu 9, Longshu 3, and Atlantic), two levels of water (Well watered and drought) application and aphid infestation (Aphids and no aphids) was conducted. The results show that drought stress and aphid infestation significantly increased the root-projected area, root surface area, number of root tips, and number of root forks of all cultivars, relative to their corresponding control plants. The least root projected area, root surface area, number of root tips, and number of root forks occurred on DXY under both drought and aphid infestation. Nevertheless, the greatest root projected area, root surface area, number of root tips and number of root forks occurred on QS9 plants. Moreover, increased SOD, CAT, and POD activities were observed across all cultivars, under drought and aphid stress. The highest SOD, POD, and CAT activities occurred in QS9; under drought and aphid stress, while the least SOD, POD, and CAT activities was observed in DXY. The Atlantic cultivar, which possesses a root system sensitive to water deficit, demonstrated greater resistance to aphid infestation under well-watered and drought-stressed conditions. Conversely, Qingshu 9, which possesses a root system tolerant to water deficit, was highly susceptible to aphids. This study shows that the root architectural and biochemical traits that enhance potato tolerance to drought do not necessarily correlate to a plant’s tolerance to aphids.

scholarly journals Quantitative Phosphoproteomic Analysis of Soybean Root Hairs Inoculated with Bradyrhizobium japonicum

2012 ◽  
Vol 11 (11) ◽  
pp. 1140-1155 ◽  
Author(s):  
Tran Hong Nha Nguyen ◽  
Laurent Brechenmacher ◽  
Joshua T. Aldrich ◽  
Therese R. Clauss ◽  
Marina A. Gritsenko ◽  
...  
Keyword(s):  
Root Hair ◽  
Bradyrhizobium Japonicum ◽  
Cell Biology ◽  
Magnetic Beads ◽  
Critical Role ◽  
Root Hairs ◽  
Root Surface ◽  
Infection Process ◽  
Root Surface Area ◽  
Soybean Root

Root hairs are single hair-forming cells on roots that function to increase root surface area, enhancing water and nutrient uptake. In leguminous plants, root hairs also play a critical role as the site of infection by symbiotic nitrogen fixing rhizobia, leading to the formation of a novel organ, the nodule. The initial steps in the rhizobia-root hair infection process are known to involve specific receptor kinases and subsequent kinase cascades. Here, we characterize the phosphoproteome of the root hairs and the corresponding stripped roots (i.e. roots from which root hairs were removed) during rhizobial colonization and infection to gain insight into the molecular mechanism of root hair cell biology. We chose soybean (Glycine max L.), one of the most important crop plants in the legume family, for this study because of its larger root size, which permits isolation of sufficient root hair material for phosphoproteomic analysis. Phosphopeptides derived from root hairs and stripped roots, mock inoculated or inoculated with the soybean-specific rhizobium Bradyrhizobium japonicum, were labeled with the isobaric tag eight-plex iTRAQ, enriched using Ni-NTA magnetic beads and subjected to nanoRPLC-MS/MS1 analysis using HCD and decision tree guided CID/ETD strategy. A total of 1625 unique phosphopeptides, spanning 1659 nonredundant phosphorylation sites, were detected from 1126 soybean phosphoproteins. Among them, 273 phosphopeptides corresponding to 240 phosphoproteins were found to be significantly regulated (>1.5-fold abundance change) in response to inoculation with B. japonicum. The data reveal unique features of the soybean root hair phosphoproteome, including root hair and stripped root-specific phosphorylation suggesting a complex network of kinase-substrate and phosphatase-substrate interactions in response to rhizobial inoculation.

scholarly journals Root hair phenotypes influence nitrogen acquisition in maize

2021 ◽  
Author(s):  
Patompong Saengwilai ◽  
Christopher Strock ◽  
Harini Rangarajan ◽  
Joseph Chimungu ◽  
Jirawat Salungyu ◽  
...  
Keyword(s):  
Root Hair ◽  
Structural Model ◽  
Root Hairs ◽  
Root Surface ◽  
Root Surface Area ◽  
N Availability ◽  
N Content ◽  
Nitrogen Acquisition ◽  
Field Environment ◽  
N Acquisition

Abstract Background and Aims The utility of root hairs for nitrogen (N) acquisition is poorly understood. Methods We explored the utility of root hairs for N acquisition in the functional-structural model SimRoot and with maize genotypes with variable root hair length (RHL) in greenhouse and field environments. Key Results Simulation results indicate that long, dense root hairs can improve N acquisition under varying N availability. In the greenhouse, ammonium availability had no effect on RHL and low nitrate availability increased RHL, while in the field low N reduced RHL. Longer RHL was associated with 216% increase in biomass and 237% increase in plant N content under low N conditions in the greenhouse and a 250% increase in biomass and 200% increase in plant N content in the field compared with short RHL phenotypes. In a low N field environment, genotypes with long RHL had 267% greater yield than those with short RHL. We speculate that long root hairs improve N capture by increased root surface area and expanded soil exploration beyond the N depletion zone surrounding the root surface. Conclusions We conclude that root hairs play an important role in nitrogen acquisition. We suggest that root hairs merit consideration as a breeding target for improved N acquisition in maize and other crops.

Advances in understanding plant root water uptake

2021 ◽  
pp. 373-392
Author(s):  
Mutez Ali Ahmed ◽  
◽  
Doris Vetterlein ◽  
Andrea Carminati ◽  
◽  
...  
Keyword(s):  
Crop Production ◽  
Plant Root ◽  
Root Hairs ◽  
Water Repellency ◽  
Root Water Uptake ◽  
Root Surface ◽  
Soil Matrix ◽  
Root Shrinkage ◽  
Moisture Conditions ◽  
Rhizosphere Processes

Water deficit is one of the primary limitations to crop production. Here, we review the role of root and rhizosphere hydraulic processes that affect the ability of a plant to extract water from the soil. Prominent features of rhizosphere hydraulic properties are: root shrinkage, alteration of pore geometry in the rhizosphere, effect of mucilage on water retention, hydraulic conductivity and water repellency, root hairs, and mycorrhiza connecting the root surface to the soil matrix. All these factors are strongly dynamic, changing over time and with soil moisture conditions. Although our understanding of the mechanisms related to these factors has advanced significantly in the last ten years, the relative importance of these rhizosphere processes for the ability of crops to extract water from the soil and better tolerate drought is still largely unclear. We propose that the next research step is to investigate the implications of these rhizosphere processes on crop growth and water use economy and use this knowledge to grow more resilient crops that match to their environment.

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