Root hair surface

Polyvinyl chloride cylinders -1- nylon gauze -1- device for continuous water supply Soil slices at measurable distance from soil-root interface. High bulk density of soil sampled. Nutrient uptake through an induced root hairs surface. Study of rhizosphere effect over a time and distance gradient from the soil-root interface. 47, 67, 127-129... 

Transverse section of a typical root. ° The complex features of the root hair surface that regulate reductase and other activities in metal uptake are only beginning to be understood. 

Various techniques for collection of root exudates are associated with the risk of root injury by rupture of root hairs and epidermal cells or rapid change of the environmental conditions (e.g., temperature, pH, oxygen availability) during transfer of root systems into trap solutions, application of absorbtion materials onto the root surface, and preparation of root systems for exudate collection. The possible impact of those stress treatments may be assessed by measuring parameters of plant growth in plants either. subjected or not subjected to the collection procedure (6) and by comparing exudation patterns after exposure of roots to the handling procedures with different intensity. 

The classic Barber-Cushman model treats the root surface as a smooth solid cylinder. Yet many experimental studies have shown that root hairs are important for the uptake of some nutrients, e.g., P (25,26). Various mathematical models for root hairs have been used (5,27,28), which all differ slightly in the way in which root hairs are modeled. Most authors conclude that root hairs make a substantial contribution to uptake, particularly for relatively immobile nutrients. 

Compare the surface to volume ratios for an E. coli cell, a liver cell, the nucleus of a eukaryotic cell, a root hair. If a cell of 20 pm diameter is 20% covered with microvilli of 0.1 pm diameter and 1 pm length centered on a 0.2 pm spacing, how much will the surface/volume ratio be increased ... 

Studies on the white clover -Rhizobium trifolii interaction are the most advanced. Trifoliin A, a lectin present in clover-seedling roots, binds hapten reversibly to carbohydrate antigens cross-reactive on the capsular polysaccharide of R. trifolii and clover epidermal-cells.244 A specific hapten that inhibits binding of trifoliin A to both surfaces is 2-deoxy-D-arabino-hexose.245 It has also been shown that levels of trifoliin A on root hairs decline with increasing concentrations of nitrate, in parallel to root-nodule development,246 and that lectin receptors are transient on R. trifolii, in a way coinciding with its capacity to be adsorbed to clover roots.247... 

Also, Schmidt et al. (2005) found a significant increase in root hair density by working with Arabidopsis thaliana, which were treated with water extractable humic substances (WEHS), suggesting that these substances induce a nutrient acquisition response that favors the uptake of nutrients via an increase in the absorptive surface area. Furthermore, a phenotypical analysis of an array of mutants harbouring defects in root epidermal patterning revealed that root hair density of the ttg and gl2 mutants, defective in cell specification, was significantly modified, indicating an effect at/or downstream of the determination of the cells. 

The influx of water is enhanced by root hairs, which protrude from the epidermal cells (see Fig. 1-4). They are often about 12 jim in diameter, up to 1 mm long, and usually vary in frequency from 0.5 to 50 per mm2. Compared to water entry into young roots, Jv can be only 1 to 5% as much for older roots, because their outer surfaces lack root hairs and generally become extensively cutinized and suberized. 

Hypha (plural, hyphae)—Cellular unit of a fungus, typically a branched and tubular filament. Many strands (hyphae) together are called mycelium. Root hair—These are tiny, tubular outgrowths of the root epidermis, mostly occurring behind the actively growing root tip, and used to increase surface area of the root to enhance the absorption of minerals and water from the soil. 

The functions of a root are absorption, storage and support. Its principal function is the absorption of nutriment and to this end it generally has branches of rootlets covered with root-hairs which largely increase the absorbing surface. These root-hairs are of DigitizedMicrosoft ... 

The entire root system of a single plant, exclusive of root hairs, totalled 13,815,672 members with a surface area of approximately 2,554 sq. ft. The combined length of all roots was 387 miles, distributed as follows main roots, O.04 miles secondary roots, 3.37 miles tertiary roots, 108.74 miles and very fine quaternary roots, 275 miles. 

Root hairs were scattered over the entire surface of all roots of this rye plant, the... 

THE NUMBER, LENGTH AND SURFACE OF THE ROOTS, OTHER THAN ROOT HAIRS, ON A SINGLE RYE PLANT (from DITTMER, 1937)... 

Plant and other lectins have the ability to adhere strongly to microbial cell surfaces and lectins are responsible for the adhesion of Rhizobim trifotii to root hair cells of clover. Discovery of lectins which will bind other microbes may lead to the use of lectins as bridging agents to bind cells to inert support materials. Fletcher (83) studied the effects of proteins on the adhesion of a marine Pseudomonas sp. to polystyrene Petri dishes. Bovine serum albumin, gelatin, fibrinogen and pepsin (pKj — 5.8) all inhibit attachment at pH 7.6 when present either prior to or concurrently with the microbial cells. Bovine serum albumin decreased the adhesion of previously attached cells. 

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