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Niels Erik Nielsen - One of the best experts on this subject based on the ideXlab platform.
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barley genotypes with long Root Hairs sustain high grain yields in low p field
Plant and Soil, 2004Co-Authors: Tara S Gahoonia, Niels Erik NielsenAbstract:Superior Root traits, like long Root Hairs, enhance phosphorus (P) uptake and hence the selection for Root hair trait offers the possibility to sustain yields in low-P soils. It is yet unknown whether Root hair promoted P uptake of barley genotypes is related to the grain yield in low -P field soil. To investigate this, a set of barley genotypes was pre-screened using hydroponics for long (about 1 mm, cvs. Pongo, Linus Barke, Tofta, Henni) and short Root Hairs (about 0.5 mm, cvs. AC91/5606/17, Meltan, Scarlett, Century, Otira, and Cecilia). The selected genotypes were cultivated in low-P field plots (no P in 35 years, 3 µM P in soil solution) and in plots amended by moderate (10 kg Ph a −1 ,6 µM P in soil solution) and high (20 kg P ha −1 ,1 0µM P in soil solution) P fertilisation. The ranking of the genotypes Root Hairs in laboratory remained consistence in the field, except for cv. Barke (1.05 mm). The genotypes varied in specific Root length (SRL, m g −1 ) and Root hair length (RHL), but the estimated volume of soil explored by Root system clearly depended on RHL. The correlations of RHL (R 2 = 0.60 ∗∗∗ ), volume of soil explored by Root system (R 2 = 0.57 ∗∗∗ )a nd SRL (R 2 = 0.40 ∗∗ ) with the P uptake in the field were highly significant. The correlation of Root-shoot ratio with the P uptake was non-significant (R 2 = 0.11). The genotypes with long Root Hairs preserved economical stable grain yield in low, moderate and high P plots. In contrast, the genotypes with short Root Hairs produced lower grain yield in low P soil, but they responded to moderate and high P fertilisation by significant increase in their grain yields. From the results of this field-based case study, it is concluded that barley genotypes with long Root Hairs are better adapted in low P soils and they express high yield potentials both in low and high P soils.
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a Root hairless barley mutant for elucidating genetic of Root Hairs and phosphorus uptake
Plant and Soil, 2001Co-Authors: Tara Singh Gahoonia, Niels Erik Nielsen, Priyavadan A Joshi, A JahoorAbstract:This paper reports a new barley mutant missing Root Hairs. The mutant was spontaneously discovered among the population of wild type (Pallas, a spring barley cultivar), producing normal, 0.8 mm long Root Hairs. We have called the mutant bald Root barley (brb). Root anatomical studies confirmed the lack of Root Hairs on mutant Roots. Amplified Fragment Length Polymorphism (AFLP) analyses of the genomes of the mutant and Pallas supported that the brb mutant has its genetic background in Pallas. The segregation ratio of selfed F2 plants, resulting from mutant and Pallas outcross, was 1:3 (−Root Hairs:+Root Hairs), suggesting a monogenic recessive mode of inheritance.
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direct evidence on participation of Root Hairs in phosphorus 32 p uptake from soil
Plant and Soil, 1998Co-Authors: Tara Singh Gahoonia, Niels Erik NielsenAbstract:Root Hairs substantially extend Root surface for ion uptake. Although many reports suggest a relationship between Root Hairs and phosphorus (P) uptake of plants, the role of Root Hairs in phosphorus uptake from soils is still debated. We measured uptake of phosphorus from soil directly via Root Hairs. Root Hairs only were allowed to penetrate through a tightly stretched nylon screen (53 µm) glued to the bottom of a PVC tube. The penetrating Root Hairs grew for 2 and 4 days in soil labelled with radioisotope phosphorus (P) tracer 32P (185 kBq g-1 dry soil) filled in another PVC tube. Transparent plastic rings of thickness ranging from 0.25 mm to 2.0 mm were inserted between the two PVC tubes. This provided slit width for microscopic observations in situ, which confirmed that only Root Hairs were growing into the 32P labelled soil. In some cases no rings were inserted (slit width = 0) where both Root Hairs and Root surface were in contact with the labelled soil (total 32P uptake). The uptake of32 P from soil via the Root Hairs only was quantified by measuring activity of 32P in the plant shoot (32P uptake only via Root Hairs).
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variation in Root Hairs of barley cultivars doubled soil phosphorus uptake
Euphytica, 1997Co-Authors: Tara Singh Gahoonia, Niels Erik NielsenAbstract:Summary Length and density (number mm 1 Root) of Root Hairs of two barley (Hordeum vulgareL.) cultivars Salka and Zita and their capability to absorb phosphorus (P) from nutrient solution as well as from rhizosphere soil were studied. The cultivars were chosen because they differed most among 30 cultivars in ability to absorb P from low P soil in two field conditions. In nutrient solution culture, Salka had 32 4 Root Hairs mm 1 Root, 1.02 0.22 mm long. Zita had 21 3h airs mm 1 Root, 0.54 0.14 mm long. In soil, the Root Hairs of both the cultivars were slightly longer (Salka 1.10 0.16 mm; Zita 0.63 0.18 mm) than in solution culture but the difference was non-significant (p 0.05). The Root Hairs increased the effective Root surface area of Salka by 206% and that of Zita by 81%. In solution culture, Salka produced 163 9m g 1 and Zita 153 11 m g 1 dry Roots in 21 days. Salka produced 1.65 0.22 g and Zita 1.51 0.31 g of green dry matter (DM). The cultivars did not differ in uptake of P from nutrient solution culture. The P content of DM was 0.42 0.1% in Salka and 0.41 0.08% in Zita. In soil, Salka depleted two times more P from rhizosphere than Zita. The longer Root Hairs of Salka increased the extension of the depletion zone for NaHCO3-P (inorganic P extracted with 0.5 M NaHCO3) in the rhizosphere. The cultivars also depleted NaOH-Pi (inorganic P extracted with 0.1 M NaOH) from the rhizosphere soil, but the difference between the cultivars was non-significant (p 0.05). The results suggested that the ability of Salka to absorb more inorganic soil P was due to its longer and denser Root Hairs.
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Root Hairs and phosphorus acquisition of wheat and barley cultivars
Plant and Soil, 1997Co-Authors: Tara Singh Gahoonia, Debbie Care, Niels Erik NielsenAbstract:Root-soil contact is an important factor for uptake of a less mobile soil nutrient such as phosphorus (P) by crop plants. Root Hairs can substantially increase Root-soil contact. Identification of crop cultivars with more and longer Root Hairs can, therefore, be useful for increasing P uptake in low input agriculture. We studied the Root Hairs of wheat (Triticum aestivum L. cvs. Kosack, Foreman, Kraka) and barley cultivars (Hordeum vulgare L. cvs. Angora, Hamu, Alexis, Canut) in relation to P depletion from the rhizosphere in three soils of different P levels (0.45, 1.1 and 1.6 mmoles P kg−1 soil; extracted with 0.5 M NaHCO3). Root Hairs were measured in solution culture having nutrients and concentration similar to soil solution. Root Hairs of Kraka were much longer (1.27 ± 0.26 mm) and denser (38 ± 3) Hairs mm−1 Root) than those of Kosack which had shorter (0.49 ± 0.2 mm) and fewer (24 ± 3) Hairs mm−1 Root) Root Hairs. Root Hairs increased Root surface area (RSA) of Kraka by 341%. The increase with Foreman was 142% and with Kosack it was 95%. For winter barley, the length (1.1 ± 0.3 mm) and density (30 ± 1 Hairs mm−1 Root) of Root Hairs of Hamu differed from Root hair length (0.52 ± 0.18 mm) and density (27 ± 1 Hairs mm−1 Root) of Angora. Root Hairs of spring barley cultivars differed in length (Canut 1.0 ± 0.24 mm; Alexis 0.64 ± 0.19 mm) but not in density (Canut 31 ± 1, Alexis 30 ± 2 Hairs mm−1 Root). Root hair diameter (12 ± 1µm) did not differ among the cultivars. Root Hairs increased RSA of Canut by 245%, Hamu by 237%, Alexis by 143% and Angora 112%. The variation in Root hair parameters of the cultivars was related to quantity of P depleted from rhizosphere. The correlation (R2) between the Root hair lengths of wheat cultivars and the quantity of P depleted from the rhizosphere soil (Q) was (0.99***) in low-P, (0.85***) in medium-P and (0.78**) in high-P soil. The values of (R2) between the Root hair surface areas of wheat cultivars and Q were (1.00***) in low-P, (0.74**) in medium-P and (0.66**) in high-P soil. Similar high values of R2 were found for barley. These results show that the variation in Root Hairs of cereal cultivars can be considerable and it can play a significant role in P acquisition, especially in low-P soils.
Liam Dolan - One of the best experts on this subject based on the ideXlab platform.
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do longer Root Hairs improve phosphorus uptake testing the hypothesis with transgenic brachypodium distachyon lines overexpressing endogenous rsl genes
New Phytologist, 2018Co-Authors: Liam Dolan, Emmanuel Delhaize, Chunyan Zhang, Richard J Simpson, Norman Warthmann, Mary E Byrne, Yu Wu, Peter R RyanAbstract:: Mutants without Root Hairs show reduced inorganic orthophosphate (Pi) uptake and compromised growth on soils when Pi availability is restricted. What is less clear is whether Root Hairs that are longer than wild-type provide an additional benefit to phosphorus (P) nutrition. This was tested using transgenic Brachypodium lines with longer Root Hairs. The lines were transformed with the endogenous BdRSL2 and BdRSL3 genes using either a constitutive promoter or a Root hair-specific promoter. Plants were grown for 32 d in soil amended with various Pi concentrations. Plant biomass and P uptake were measured and genotypes were compared on the basis of critical Pi values and P uptake per unit Root length. Ectopic expression of RSL2 and RSL3 increased Root hair length three-fold but decreased plant biomass. Constitutive expression of BdRSL2, but not expression of BdRSL3, consistently improved P nutrition as measured by lowering the critical Pi values and increasing Pi uptake per unit Root length. Increasing Root hair length through breeding or biotechnology can improve P uptake efficiency if the pleotropic effects on plant biomass are avoided. Long Root Hairs, alone, appear to be insufficient to improve Pi uptake and need to be combined with other traits to benefit P nutrition.
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the evolution of Root Hairs and rhizoids
Annals of Botany, 2012Co-Authors: Victor A S Jones, Liam DolanAbstract:BACKGROUND: Almost all land plants develop tip-growing filamentous cells at the interface between the plant and substrate (the soil). Root Hairs form on the surface of Roots of sporophytes (the multicellular diploid phase of the life cycle) in vascular plants. Rhizoids develop on the free-living gametophytes of vascular and non-vascular plants and on both gametophytes and sporophytes of the extinct rhyniophytes. Extant lycophytes (clubmosses and quillworts) and monilophytes (ferns and horsetails) develop both free-living gametophytes and free-living sporophytes. These gametophytes and sporophytes grow in close contact with the soil and develop rhizoids and Root Hairs, respectively. SCOPE: Here we review the development and function of rhizoids and Root Hairs in extant groups of land plants. Root Hairs are important for the uptake of nutrients with limited mobility in the soil such as phosphate. Rhizoids have a variety of functions including water transport and adhesion to surfaces in some mosses and liverworts. CONCLUSIONS: A similar gene regulatory network controls the development of rhizoids in moss gametophytes and Root Hairs on the Roots of vascular plant sporophytes. It is likely that this gene regulatory network first operated in the gametophyte of the earliest land plants. We propose that later it functioned in sporophytes as the diploid phase evolved a free-living habit and developed an interface with the soil. This transference of gene function from gametophyte to sporophyte could provide a mechanism that, at least in part, explains the increase in morphological diversity of sporophytes that occurred during the radiation of land plants in the Devonian Period.
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The evolution of Root Hairs and rhizoids
Annals of Botany, 2012Co-Authors: Victor A S Jones, Liam DolanAbstract:Background Almost all land plants develop tip-growing filamentous cells at the interface between the plant and substrate (the soil). Root Hairs form on the surface of Roots of sporophytes (the multicellular diploid phase of the life cycle) in vascular plants. Rhizoids develop on the free-living gametophytes of vascular and non-vascular plants and on both gametophytes and sporophytes of the extinct rhyniophytes. Extant lycophytes (clubmosses and quillworts) and monilophytes (ferns and horsetails) develop both free-living gametophytes and free-living sporophytes. These gametophytes and sporophytes grow in close contact with the soil and develop rhizoids and Root Hairs, respectively.
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Root Hairs development growth and evolution at the plant soil interface
Plant and Soil, 2011Co-Authors: Sourav Datta, Monica Pernas, Nuno Pires, Helene Proust, Priya Vijayakumar, Liam DolanAbstract:Root Hairs are tip-growing extensions from Root epidermal cells that play important roles in nutrient uptake and in plant-soil interactions. In this review, we discuss the major environmental, physiological and genetic factors that regulate the differentiation and growth of Root Hairs in angiosperms. Root hair cells are arranged in a number of different patterns in the Root epidermis of different species. In Arabidopsis (Arabidopsis thaliana L.), a striped pattern of hair and non-hair files is generated by an intercellular gene regulatory network that involves feedback loops and protein movement between neighbouring cells. The growth of Root Hairs can be broadly divided into an initiation phase, where site selection and bulge formation take place, and an elongation phase. The initiation phase is regulated by different transcription factors, GTPases and cell wall modification enzymes. During the elongation phase Root Hairs grow by tip growth, a type of polarised cell expansion that is restricted to the growing apex. Root hair elongation is characterized by a strong polarisation of the cytoskeleton, active cell wall modifications and dynamic ion movements. Finally, we discuss the functional and genetic similarities between the Root Hairs of angiosperms and the rhizoids of bryophytes and ferns.
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a basic helix loop helix transcription factor controls cell growth and size in Root Hairs
Nature Genetics, 2010Co-Authors: Keke Yi, Liam Dolan, Benoit Menand, Elizabeth BellAbstract:Postmitotic cell growth defines cell shape and size during development. However, the mechanisms regulating postmitotic cell growth in plants remain unknown. Here we report the discovery of a basic helix-loop-helix (bHLH) transcription factor called RSL4 (Root HAIR DEFECTIVE 6-LIKE 4) that is sufficient to promote postmitotic cell growth in Arabidopsis thaliana Root-hair cells. Loss of RSL4 function resulted in the development of very short Root Hairs. In contrast, constitutive RSL4 expression programmed constitutive growth, resulting in the formation of very long Root Hairs. Hair-cell growth signals, such as auxin and low phosphate availability, modulate hair cell extension by regulating RSL4 transcript and protein levels. RSL4 is thus a regulator of growth that integrates endogenous developmental and exogenous environmental signals that together control postmitotic growth in Root Hairs. The control of postmitotic growth by transcription factors may represent a general mechanism for regulating cell size across diverse organisms.
Wolfgang Schmidt - One of the best experts on this subject based on the ideXlab platform.
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an inventory of nutrient responsive genes in arabidopsis Root Hairs
Frontiers in Plant Science, 2016Co-Authors: Jorge E Salazarhenao, Wolfgang SchmidtAbstract:Root Hairs, single cell extensions of Root epidermal cells that are critically involved in the acquisition of mineral nutrients, have proven to be an excellent model system for studying plant cell growth. More recently, omics-based systems biology approaches have extended the model function of Root Hairs towards functional genomic studies. While such studies are extremely useful to decipher the complex mechanisms underlying Root hair morphogenesis, their importance for the performance and fitness of the plant puts Root Hairs in the spotlight of research aimed at elucidating aspects with more practical implications. Here, we mined transcriptomic and proteomic surveys to catalog genes that are preferentially expressed in Root Hairs and responsive to nutritional signals. We refer to this group of genes as the Root hair trophomorphome. Our analysis shows that the activity of genes within the trophomorphome is regulated at both the transcriptional and post-transcriptional level with the mode of regulation being related to the function of the gene product. A core set of proteins functioning in cell wall modification and protein transport was defined as the backbone of the trophomorphome. In addition, our study shows that homeostasis of reactive oxygen species and redox regulation plays a key role in Root hair trophomorphogenesis.
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mapping gene activity of arabidopsis Root Hairs
Genome Biology, 2013Co-Authors: Wenfeng Li, Simonetta Santi, Wolfgang SchmidtAbstract:Background: Quantitative information on gene activity at single cell-type resolution is essential for the understanding of how cells work and interact. Root Hairs, or trichoblasts, tubular-shaped outgrowths of specialized cells in the epidermis, represent an ideal model for cell fate acquisition and differentiation in plants. Results: Here, we provide an atlas of gene and protein expression in Arabidopsis Root hair cells, generated by paired-end RNA sequencing and LC/MS-MS analysis of protoplasts from plants containing a pEXP7-GFP reporter construct. In total, transcripts of 23,034 genes were detected in Root Hairs. High-resolution proteome analysis led to the reliable identification of 2,447 proteins, 129 of which were differentially expressed between Root Hairs and nonRoot hair tissue. Dissection of pre-mRNA splicing patterns showed that all types of alternative splicing were cell type-dependent, and less complex in EXP7-expressing cells when compared to non-Root hair cells. Intron retention was repressed in several transcripts functionally related to Root hair morphogenesis, indicative of a cell type-specific control of gene expression by alternative splicing of pre-mRNA. Concordance between mRNA and protein expression was generally high, but in many cases mRNA expression was not predictive for protein abundance. Conclusions: The integrated analysis shows that gene activity in Root Hairs is dictated by orchestrated, multilayered regulatory mechanisms that allow for a cell type-specific composition of functional components.
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laser microdissection assisted analysis of the functional fate of iron deficiency induced Root Hairs in cucumber
Journal of Experimental Botany, 2008Co-Authors: Simonetta Santi, Wolfgang SchmidtAbstract:: Iron ranks fourth in the sequence of abundance of the elements in the Earth's crust, but its low bio-availability often limits plant growth. When present in suboptimal amounts, the acquisition of iron by plants is aided by a suite of responses, comprising molecular and developmental changes that facilitate the uptake of iron from sparingly soluble pools. The expression of genes involved in the mobilization of iron (CsHA1), the reduction of ferric chelates (CsFRO1), and in the uptake of ferrous iron (CsIRT1) was investigated in epidermal cells of Fe-sufficient and Fe-deficient cucumber (Cucumis sativum L.) Roots using the Laser Microdissection and Pressure Catapulting (LMPC) method. Growing plants hydroponically in media deprived of iron induced the differentiation of almost all epidermal cells into Root Hairs. No Root Hairs were formed under iron-replete conditions. The formation of Root Hairs in response to Fe starvation was associated with a dramatic increase in message levels of CsFRO1, CsIRT1, and the iron-inducible H(+)-ATPase isoform CsHA1, when compared to epidermal cells of Fe-sufficient plants. On the contrary, transcripts of a housekeeping ATPase isoform, CsHA2, were not detected in Root Hairs, suggesting that Fe-deficiency-induced acidification is predominantly mediated by CsHA1. These data show that the formation of Root Hairs in response to iron deficiency is associated with cell-specific accumulation of transcripts that are involved in iron acquisition. The results also show that this includes the differential regulation of ATPase isoforms with similar function, but supposedly different characteristics, to counteract the imbalance in nutrient supply efficiently.
Tara Singh Gahoonia - One of the best experts on this subject based on the ideXlab platform.
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a Root hairless barley mutant for elucidating genetic of Root Hairs and phosphorus uptake
Plant and Soil, 2001Co-Authors: Tara Singh Gahoonia, Niels Erik Nielsen, Priyavadan A Joshi, A JahoorAbstract:This paper reports a new barley mutant missing Root Hairs. The mutant was spontaneously discovered among the population of wild type (Pallas, a spring barley cultivar), producing normal, 0.8 mm long Root Hairs. We have called the mutant bald Root barley (brb). Root anatomical studies confirmed the lack of Root Hairs on mutant Roots. Amplified Fragment Length Polymorphism (AFLP) analyses of the genomes of the mutant and Pallas supported that the brb mutant has its genetic background in Pallas. The segregation ratio of selfed F2 plants, resulting from mutant and Pallas outcross, was 1:3 (−Root Hairs:+Root Hairs), suggesting a monogenic recessive mode of inheritance.
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direct evidence on participation of Root Hairs in phosphorus 32 p uptake from soil
Plant and Soil, 1998Co-Authors: Tara Singh Gahoonia, Niels Erik NielsenAbstract:Root Hairs substantially extend Root surface for ion uptake. Although many reports suggest a relationship between Root Hairs and phosphorus (P) uptake of plants, the role of Root Hairs in phosphorus uptake from soils is still debated. We measured uptake of phosphorus from soil directly via Root Hairs. Root Hairs only were allowed to penetrate through a tightly stretched nylon screen (53 µm) glued to the bottom of a PVC tube. The penetrating Root Hairs grew for 2 and 4 days in soil labelled with radioisotope phosphorus (P) tracer 32P (185 kBq g-1 dry soil) filled in another PVC tube. Transparent plastic rings of thickness ranging from 0.25 mm to 2.0 mm were inserted between the two PVC tubes. This provided slit width for microscopic observations in situ, which confirmed that only Root Hairs were growing into the 32P labelled soil. In some cases no rings were inserted (slit width = 0) where both Root Hairs and Root surface were in contact with the labelled soil (total 32P uptake). The uptake of32 P from soil via the Root Hairs only was quantified by measuring activity of 32P in the plant shoot (32P uptake only via Root Hairs).
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variation in Root Hairs of barley cultivars doubled soil phosphorus uptake
Euphytica, 1997Co-Authors: Tara Singh Gahoonia, Niels Erik NielsenAbstract:Summary Length and density (number mm 1 Root) of Root Hairs of two barley (Hordeum vulgareL.) cultivars Salka and Zita and their capability to absorb phosphorus (P) from nutrient solution as well as from rhizosphere soil were studied. The cultivars were chosen because they differed most among 30 cultivars in ability to absorb P from low P soil in two field conditions. In nutrient solution culture, Salka had 32 4 Root Hairs mm 1 Root, 1.02 0.22 mm long. Zita had 21 3h airs mm 1 Root, 0.54 0.14 mm long. In soil, the Root Hairs of both the cultivars were slightly longer (Salka 1.10 0.16 mm; Zita 0.63 0.18 mm) than in solution culture but the difference was non-significant (p 0.05). The Root Hairs increased the effective Root surface area of Salka by 206% and that of Zita by 81%. In solution culture, Salka produced 163 9m g 1 and Zita 153 11 m g 1 dry Roots in 21 days. Salka produced 1.65 0.22 g and Zita 1.51 0.31 g of green dry matter (DM). The cultivars did not differ in uptake of P from nutrient solution culture. The P content of DM was 0.42 0.1% in Salka and 0.41 0.08% in Zita. In soil, Salka depleted two times more P from rhizosphere than Zita. The longer Root Hairs of Salka increased the extension of the depletion zone for NaHCO3-P (inorganic P extracted with 0.5 M NaHCO3) in the rhizosphere. The cultivars also depleted NaOH-Pi (inorganic P extracted with 0.1 M NaOH) from the rhizosphere soil, but the difference between the cultivars was non-significant (p 0.05). The results suggested that the ability of Salka to absorb more inorganic soil P was due to its longer and denser Root Hairs.
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Root Hairs and phosphorus acquisition of wheat and barley cultivars
Plant and Soil, 1997Co-Authors: Tara Singh Gahoonia, Debbie Care, Niels Erik NielsenAbstract:Root-soil contact is an important factor for uptake of a less mobile soil nutrient such as phosphorus (P) by crop plants. Root Hairs can substantially increase Root-soil contact. Identification of crop cultivars with more and longer Root Hairs can, therefore, be useful for increasing P uptake in low input agriculture. We studied the Root Hairs of wheat (Triticum aestivum L. cvs. Kosack, Foreman, Kraka) and barley cultivars (Hordeum vulgare L. cvs. Angora, Hamu, Alexis, Canut) in relation to P depletion from the rhizosphere in three soils of different P levels (0.45, 1.1 and 1.6 mmoles P kg−1 soil; extracted with 0.5 M NaHCO3). Root Hairs were measured in solution culture having nutrients and concentration similar to soil solution. Root Hairs of Kraka were much longer (1.27 ± 0.26 mm) and denser (38 ± 3) Hairs mm−1 Root) than those of Kosack which had shorter (0.49 ± 0.2 mm) and fewer (24 ± 3) Hairs mm−1 Root) Root Hairs. Root Hairs increased Root surface area (RSA) of Kraka by 341%. The increase with Foreman was 142% and with Kosack it was 95%. For winter barley, the length (1.1 ± 0.3 mm) and density (30 ± 1 Hairs mm−1 Root) of Root Hairs of Hamu differed from Root hair length (0.52 ± 0.18 mm) and density (27 ± 1 Hairs mm−1 Root) of Angora. Root Hairs of spring barley cultivars differed in length (Canut 1.0 ± 0.24 mm; Alexis 0.64 ± 0.19 mm) but not in density (Canut 31 ± 1, Alexis 30 ± 2 Hairs mm−1 Root). Root hair diameter (12 ± 1µm) did not differ among the cultivars. Root Hairs increased RSA of Canut by 245%, Hamu by 237%, Alexis by 143% and Angora 112%. The variation in Root hair parameters of the cultivars was related to quantity of P depleted from rhizosphere. The correlation (R2) between the Root hair lengths of wheat cultivars and the quantity of P depleted from the rhizosphere soil (Q) was (0.99***) in low-P, (0.85***) in medium-P and (0.78**) in high-P soil. The values of (R2) between the Root hair surface areas of wheat cultivars and Q were (1.00***) in low-P, (0.74**) in medium-P and (0.66**) in high-P soil. Similar high values of R2 were found for barley. These results show that the variation in Root Hairs of cereal cultivars can be considerable and it can play a significant role in P acquisition, especially in low-P soils.
Tiina Roose - One of the best experts on this subject based on the ideXlab platform.
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high resolution synchrotron imaging of wheat Root Hairs growing in soil and image based modelling of phosphate uptake
New Phytologist, 2013Co-Authors: Samuel D Keyes, Keith R Daly, Alan Marchant, Neil J Gostling, Davey L Jones, Peter J Talboys, Bernd R Pinzer, Richard P Boardman, I Sinclair, Tiina RooseAbstract:Root Hairs are known to be highly important for uptake of sparingly soluble nutrients, particularly in nutrient deficient soils. Development of increasingly sophisticated mathematical models has allowed uptake characteristics to be quantified. However, modelling has been constrained by a lack of methods for imaging live Root Hairs growing in real soils. We developed a plant growth protocol and used Synchrotron Radiation X-ray Tomographic Microscopy (SRXTM) to uncover the 3D interactions of Root Hairs in real soil. We developed a model of phosphate uptake by Root Hairs based directly on the geometry of Hairs and associated soil pores as revealed by imaging. Previous modelling studies found that Root Hairs dominate phosphate uptake. By contrast, our study suggests that Hairs and Roots contribute equally. We show that uptake by Hairs is more localised than by Roots and strongly dependent on Root hair and aggregate orientation. The ability to image hair-soil interactions enables a step change in modelling approaches, allowing a more realistic treatment of processes at the scale of individual Root Hairs in soil pores.
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a dual porosity model of nutrient uptake by Root Hairs
New Phytologist, 2011Co-Authors: Kostas Zygalakis, G J D Kirk, Davey L Jones, Matthias Wissuwa, Tiina RooseAbstract:Summary • The importance of Root Hairs in the uptake of sparingly soluble nutrients is understood qualitatively, but not quantitatively, and this limits efforts to breed plants tolerant of nutrient-deficient soils. • Here, we develop a mathematical model of nutrient uptake by Root Hairs allowing for hair geometry and the details of nutrient transport through soil, including diffusion within and between soil particles. We give illustrative results for phosphate uptake. • Compared with conventional ‘single porosity’ models, this ‘dual porosity’ model predicts greater Root uptake because more nutrient is available by slow release from within soil particles. Also the effect of soil moisture is less important with the dual porosity model because the effective volume available for diffusion in the soil is larger, and the predicted effects of hair length and density are different. • Consistent with experimental observations, with the dual porosity model, increases in hair length give greater increases in uptake than increases in hair density per unit main Root length. The effect of hair density is less in dry soil because the minimum concentration in solution for net influx is reached more rapidly. The effect of hair length is much less sensitive to soil moisture.
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a dynamic model of nutrient uptake by Root Hairs
New Phytologist, 2010Co-Authors: Daniel Leitner, Sabine Klepsch, Mariya Ptashnyk, Alan Marchant, G J D Kirk, Andrea Schnepf, Tiina RooseAbstract:• Root Hairs are known to be important in the uptake of sparingly soluble nutrients by plants, but quantitative understanding of their role in this is weak. This limits, for example, the breeding of more nutrient-efficient crop genotypes. • We developed a mathematical model of nutrient transport and uptake in the Root hair zone of single Roots growing in soil or solution culture. Accounting for Root hair geometry explicitly, we derived effective equations for the cumulative effect of Root hair surfaces on uptake using the method of homogenization. • Analysis of the model shows that, depending on the morphological and physiological properties of the Root Hairs, one of three different effective models applies. They describe situations where: (1) a concentration gradient dynamically develops within the Root hair zone; (2) the effect of Root hair uptake is negligibly small; or (3) phosphate in the Root hair zone is taken up instantaneously. Furthermore, we show that the influence of Root Hairs on rates of phosphate uptake is one order of magnitude greater in soil than solution culture. • The model provides a basis for quantifying the importance of Root hair morphological and physiological properties in overall uptake, in order to design and interpret experiments in different circumstances.
