scholarly journals Physiological Regulation of Root System Architecture: The Role of Ethylene and Phosphorus

2001 ◽  
Author(s):  
Amram Eshel ◽  
Jonathan P. Lynch ◽  
Kathleen M. Brown
Keyword(s):  
Root System ◽  
Root Hair ◽  
Ethylene Production ◽  
Root Architecture ◽  
Root Hairs ◽  
Phosphorus Availability ◽  
Hair Density ◽  
Root Angle ◽  
Low Phosphorus ◽  
Root Hair Density

Specific Objectives and Related Results: 1) Determine the effect of phosphorus availability on ethylene production by roots. Test the hypothesis that phosphorus availability regulates ethylene production Clear differences were found between the two plants that were studied. In beans ethylene production is affected by P nutrition, tissue type, and stage of development. There are genotypic differences in the rate of ethylene production by various root types and in the differential in ethylene production when P treatments are compared. The acceleration in ethylene production with P deficiency increases with time. These findings support the hypothesis that ethylene production may be enhanced by phosphorus deficiency, and that the degree of enhancement varies with genotype. In tomatoes the low-P level did not enhance significantly ethylene production by the roots. Wildtype cultivars and ethylene insensitive mutants behaved similarly in that respect. 2) Characterize the effects of phosphorus availability and ethylene on the architecture of whole root systems. Test the hypothesis that both ethylene and low phosphorus availability modify root architecture. In common bean, the basal roots give rise to a major fraction of the whole root system. Unlike other laterals these roots respond to gravitropic stimulation. Their growth angle determines the proportion of the root length in the shallow layers of the soil. A correlation between ethylene production and basal root angle was found in shallow rooted but not deep-rooted genotypes, indicating that acceleration of ethylene synthesis may account for the change in basal root angle in genotypes demonstrating a plastic response to P availability. Short-time gravitropic response of the tap roots of young bean seedlings was not affected by P level in the nutrient solution. Low phosphorus specifically increases root hair length and root hair density in Arabidopsis. We tested 7 different mutants in ethylene perception and response and in each case, the response to low P was lower than that of the wild-type. The extent of reduction in P response varied among the mutants, but every mutant retained some responsiveness to changes in P concentration. The increase in root hair density was due to the increase in the number of trichoblast cell files under low P and was not mediated by ethylene. Low P did not increase the number of root hairs forming from atrichoblasts. This is in contrast to ethylene treatment, which increased the number of root hairs partly by causing root hairs to form on atrichoblasts. 3) Assess the adaptive value of root architectural plasticity in response to phosphorus availability. A simulation study indicated that genetic variation for root architecture in common bean may be related to adaptation to diverse competitive environments. The fractal dimension of tomato root system was directly correlated with P level.

scholarly journals Regulation of root hair density by phosphorus availability in Arabidopsis thaliana

2001 ◽  
Vol 24 (4) ◽  
pp. 459-467 ◽  
Author(s):  
Z. Ma ◽  
D. G. Bielenberg ◽  
K. M. Brown ◽  
J. P. Lynch
Keyword(s):  
Arabidopsis Thaliana ◽  
Root Hair ◽  
Phosphorus Availability ◽  
Hair Density ◽  
Root Hair Density

scholarly journals Rock Fragment Content in Soils Shift Root Foraging Behavior in Xerophytic Species

2021 ◽  
Author(s):  
Hui Hu ◽  
Weikai Bao ◽  
David M. Eissenstat ◽  
Long Huang ◽  
Fanglan Li
Keyword(s):  
Root Hair ◽  
Fine Root ◽  
Root Hairs ◽  
Root Traits ◽  
Rock Fragment ◽  
Hair Density ◽  
Root Branching ◽  
Root Hair Density ◽  
Branching Intensity ◽  
Rock Fragment Content

Abstract Aims Root traits associated with resource foraging, including fine-root branching intensity, root hair and mycorrhiza, may change in soils with various physical structure indicated by rock fragment content (RFC), while how these traits covariate at the level of individual root branching order is largely unknown.Methods We subjected two xerophytic species, Artemisia vestita (subshrub) and Bauhinia brachycarpa (shrub), to increasing RFC gradients (0%, 25%, 50% and 75%, v v-1) in an arid environment and measured fine-root traits related to resource foraging.Results Root hair density and mycorrhizal colonization of both species decreased with increasing root order, but increased in 3rd- and 4th-order roots at high RFCs (50% or 75%). The two species tend to produce more root hairs than mycorrhizas under the high RFCs. For both species, root hair density and mycorrhizal colonization intensity were negatively correlated with root length and root diameter. Rockiness reduced root branching intensity in both species comparing with rock-free soil. At the same level of RFC, A. vestita had thicker roots and lower branching intensity than B. brachycarpa, and tended to produce more root hairs.Conclusion Our results suggest the high RFC soil conditions stimulated greater foraging functions in higher root orders. We found evidence for a greater investment in root hairs and mycorrhizal symbioses as opposed to building an extensive root system in rocky soils. The subshrub and shrub species took different approaches to foraging in the rocky soil through distinctive trait syndromes of fine-root components.

INFLUENCE OF ROOT HAIRS IN SUPPLYING SOIL PHOSPHORUS TO WHEAT

1973 ◽  
Vol 53 (2) ◽  
pp. 169-175 ◽  
Author(s):  
J. B. BOLE
Keyword(s):  
Root Hair ◽  
Unit Length ◽  
Root Hairs ◽  
P Uptake ◽  
Hair Density ◽  
Wheat Roots ◽  
Soil P ◽  
Root Hair Development ◽  
Root Hair Density ◽  
Hair Development

Chromosome substitution lines of wheat (Triticum aestivum L.) showing a parental difference in root-hair development were studied under several P regimes. Average root-hair density was 45 root hairs/mm in a low-P soil compared with 60 when P supply was adequate. Soil P uptake was not closely related to root-hair density in any of the regimes. Rape roots virtually devoid of root hairs took up two to six times as much soil P per unit length as the wheat roots with root hairs. Flax roots also did not produce root hairs but absorbed more P per unit length than the wheat roots. Root-hair development did not regulate the P uptake efficiency of the wheat roots and would be expected to be even less effective in supplying other nutrients.

Does the lack of root hairs alter root system architecture of Zea mays?

2021 ◽  
Author(s):  
Steffen Schlüter ◽  
Eva Lippold ◽  
Maxime Phalempin ◽  
Doris Vetterlein
Keyword(s):  
Zea Mays ◽  
Root System ◽  
Root Hair ◽  
System Architecture ◽  
Volume Fraction ◽  
Root Hairs ◽  
Root System Architecture ◽  
Root Diameter ◽  
Wild Type ◽  
Defective Mutant

<p>Root hairs are one root trait among many which enables plants to adapt to environmental conditions. How different traits are coordinated and whether some are mutually exclusive is currently poorly understood. Comparing a root hair defective mutant with its corresponding wild-type we explored if and how the mutant exhibited root growth adaption strategies and as to how far this depended on the substrate.</p><p>Zea mays root hair defective mutant (rth3) and the corresponding wild-type siblings were grown on two substrates with contrasting texture and hence nutrient mobility. Root system architecture was investigated over time using repeated X-ray computed tomography.</p><p>There was no plastic adaption of root system architecture to the lack of root hairs, which resulted in lower uptake in particular in the substrate with low P mobility. The function of the root hairs for anchoring did not result in different depth profiles of the root length density between genotypes. Both maize genotypes showed a marked response to substrate. This was well reflected in the spatiotemporal development of rhizosphere volume fraction but especially in the strong response of root diameter to substrate, irrespective of genotype.</p><p>The most salient root plasticity trait was root diameter in response to substrate, whereas coping mechanisms for missing root hairs were less evident. Further experiments are required to elucidate whether observed differences can be explained by mechanical properties beyond mechanical impedance, root or microbiome ethylene production or differences in diffusion processes within the root or the rhizosphere.</p>

scholarly journals Positional Signaling and Expression of ENHANCER OF TRY AND CPC1 Are Tuned to Increase Root Hair Density in Response to Phosphate Deficiency in Arabidopsis thaliana

PLoS ONE ◽  
2013 ◽  
Vol 8 (10) ◽  
pp. e75452 ◽  
Author(s):  
Natasha Savage ◽  
Thomas J. W. Yang ◽  
Chung Ying Chen ◽  
Kai-Lan Lin ◽  
Nicholas A. M. Monk ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Root Hair ◽  
Phosphate Deficiency ◽  
Hair Density ◽  
Root Hair Density

scholarly journals Phosphorus-induced change in root hair growth is associated with IAA accumulation in walnut

2021 ◽  
Vol 49 (4) ◽  
pp. 12504
Author(s):  
Yongjie XU ◽  
Chunyong XU ◽  
Dejian ZHANG ◽  
Xianzhen DENG
Keyword(s):  
Root Hair ◽  
Hair Growth ◽  
Juglans Regia ◽  
Root Hairs ◽  
Forest Tree ◽  
Root Surface ◽  
Nutrient Contents ◽  
Phosphorus Stress ◽  
Low Phosphorus ◽  
Root Hair Growth

Walnut, an important non-wood product forest tree, has free root hairs in orchards. Root hairs are specialized cells originating from the root epidermis that are regulated by plant hormones, such as auxins. This study was conducted to evaluate the effect and mechanism of phosphorus stress on root hair growth of walnut (Juglans regia L.) seedings by auxin (IAA) biosynthesis and transport. Both low phosphorus (LP) and no phosphorus stresses (NP) heavily decreased plant height, leaf number, total root length, root surface, shoot and root biomass, and root nutrient contents. The LP treatment significantly increased root hair growth, accompanied with up-regulation of the positive regulation root hair growth gene JrCPC and down-regulation of the negative regulation root hair growth gene JrTTG1, while the NP treatment had opposite effects. The root IAA level, IAAO activities, IAA transport genes (JrAUX1, JrLAX1, and JrPIN1), and the biosynthesis genes (JrTAA1 and JrTAR1) were increased by the LP treatment, while the NP treatment decreased all of them. Interestingly, the auxin biosynthesis gene CsYUCCA1 was not affected, which suggested that P mainly affects root hair growth of walnut by regulating auxin transport, and then affects root nutrient absorption and plant growth.

scholarly journals Genotypic variations in root traits of wheat varieties at phytomer level

2014 ◽  
Vol 12 (1) ◽  
pp. 45-54 ◽  
Author(s):  
AHK Robin ◽  
MJ Uddin ◽  
S Afrin ◽  
PR Paul
Keyword(s):  
Root Hair ◽  
Significant Variation ◽  
Root Traits ◽  
Dry Weight ◽  
Main Axis ◽  
Hair Density ◽  
Wheat Varieties ◽  
First Order ◽  
Root Hair Density ◽  
Axis Length

The aims of this study were to investigate genotypic variations in root traits at phytomer level of wheat varieties and for recommending a few root traits as selection parameters in future breeding programs. Two separate experiments were conducted to measure their root traits for hydroponically grown wheat plants. In Experiment 1, main axis length, root hair density and diameter differed from phytomer to phytomer at 60 days after sowing for two varieties, Shotabdi and Sonalika. Density of first order laterals at their axis of origin, dry weights of roots and shoots and root:shoot ratio varied significantly among 8 varieties. In Experiment 2, number of root bearing phytomer, total number of adventitious roots, main axis length at root bearing phytomer 1 and 2 (youngest roots were the reference point and numbered as phytomer 1), length of first order laterals at phytomer 3, root hair density and dry weights of roots and shoots were significantly different among varieties. PC1 (principal component 1) resulted in significant variation among varieties for number of live leaves, new roots appeared, number of root bearing phytomer, total number of adventitious roots, root dry weight and shoot dry weight. PC2 yielded significant difference among varieties for live leaves, main axes length at phytomer 1 & 2, number of new roots, root hair density and diameter. Selection of varieties based on main axes length at the youngest phytomer & root hair density per unit surface area along with dry weights of roots and shoots could be recommended for future breeding program as these four parameters consistently resulted in significant variation among varieties. DOI: http://dx.doi.org/10.3329/jbau.v12i1.21238 J. Bangladesh Agril. Univ. 12(1): 45-54, June 2014

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