Modulation of the root epidermal phenotype by hormones, inhibitors and iron regime

• Published in: Plant and soil Vol. 241; no. 1; pp. 87 - 96
• Main Authors: Schikora, Adam, Schmidt, Wolfgang
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Dordrecht Kluwer Academic Publishers 01.04.2002; Springer; Springer Nature B.V
• Subjects: 1-aminocyclopropane-1-carboxylic acid; 2,4-D; Absorption. Translocation of ions and substances. Permeability; Agronomy. Soil science and plant productions; Arabidopsis thaliana; Auxins; Biological and medical sciences; Carboxylic acids; cell differentiation; Cell walls; Classical and quantitative genetics; Classical and quantitative genetics. Population genetics. Molecular genetics; Economic plant physiology; Environmental conditions; enzyme activity; Epidermal cells; Fundamental and applied biological sciences. Psychology; Generalities. Genetics. Plant material; Genetics and breeding of economic plants; Hormones; Iron; Metabolism; Metabolism. Physicochemical requirements; nutrient availability; nutrient deficiencies; Nutrition. Photosynthesis. Respiration. Metabolism; organic acids and salts; oxidoreductases; Peas; phenotype; Plant growth regulators; plant growth substances; plant morphology; plant nutrition; Plant physiology and development; Plant roots; Plants; Root hairs; silver thiosulfate; Speciation; Water and solutes. Absorption, translocation and permeability; Biological model; Biochemistry; Iron; Antihormone; Inorganic element; Arabidopsis thaliana; Cruciferae; Dicotyledones; Modulation; Angiospermae; Lycopersicon esculentum; Solanaceae; Gene physiology; Nutrition; Root; Biochemical compound; Epidermis; Metabolic inhibitor; Bioinorganic chemistry; Ecophysiology; Phenotype; Leguminosae; Vegetable crop; Pisum sativum; Hormonal regulation; Spermatophyta; Trace element (nutrient); Phytohormone; Experimental plant; Soil plant relation
• ISSN: 0032-079X; 1573-5036
• DOI: 10.1023/A:1016089209891

Patterning of epidermal cells is subject to genetic regulation but also influenced by environmental stimuli. To adapt to unfavorable environmental conditions plants have developed various mechanisms to increase the plasma membrane's surface area of epidermal root cells, for example through the formation of root hairs and differentiation of rhizodermal transfer cells. Mechanisms controlling cell fate speciation in the rhizodermis were investigated by application of hormones and hormone antagonists. In addition, the effect of Fe deficiency on root epidermal patterning and Fe(III)-reduction activity was examined. In the iron-hyperaccumulating pea mutants dgl and brz and in the Arabidopsis mutant manl Fe(III)-reduction activity was found to be up-regulated under both high and low iron supply. In contrast, morphological responses such as the development of transfer cells and extranumerary root hairs was repressed by a high iron concentration in the external medium. All morphological responses can be mimicked by exogenous application of the ethylene precursor 1-aminocyclopropane-l-carboxylic acid (ACC) or the auxin analog 2,4-dichlorophenoxyacetic acid (2,4-D). Conversely, Fe(III)-reduction rates were not influenced or only slightly affected by the hormone treatment. Application of inhibitors of ethylene synthesis, ethylene action or auxin transport was effective only in inhibiting the formation of extra root hairs, indicating that these hormones are not required for transfer cell formation or expression of Fe(III) reduction. These data suggest that the Fe reductase induced by iron stress does not depend on the formation of transfer cells and further imply separate regulatory pathways for the two responses. The data are compatible with a model in which root reduction activity is modulated by a shoot-borne signal coordinating iron uptake with the shoot demand, while the epidermal phenotype is primarily dependent on the intracellular iron concentration of root cells.