Related Experiment Video
Updated: Aug 8, 2026
09:23
Lateral Root Inducible System in Arabidopsis and Maize
Published on: January 14, 2016
Characterization of the hexose transport system in maize root tips
1Station de Physiologie végétale, Institut National de la Recherche Agronomique, Centre de recherches de Bordeaux, 33 140 Pont de la Maye, France.
Plant Physiology
|December 1, 1988
Summary
Maize root tips exhibit complex hexose uptake systems with distinct specificities for glucose and fructose. These uptake mechanisms display biphasic kinetics, suggesting shared carrier components and concentration-dependent regulation.
Area of Science:
- Plant Physiology
- Molecular Biology
- Biochemistry
Background:
- Hexose uptake is crucial for plant growth and energy metabolism.
- Understanding sugar transport in maize roots is vital for agricultural applications.
- Previous studies faced challenges with diffusion and penetration barriers in root uptake experiments.
Purpose of the Study:
- To investigate the kinetics and specificity of hexose uptake in maize (Zea mays L.) root tips.
- To characterize the different hexose transporter systems present in maize roots.
- To develop a method for determining inhibitor constants in competition experiments.
Main Methods:
- Utilized sugar-depleted excised maize root tips to eliminate diffusion and penetration barriers.
- Analyzed hexose uptake kinetics across a range of external sugar concentrations.
- Conducted competition experiments using glucose analogs and fructose to determine transporter specificity.
Main Results:
- Identified complex, biphasic hexose uptake kinetics, indicating multiple transport systems.
- Discovered a fructose-specific uptake system, with high-affinity component repressed by high glucose concentrations.
- Characterized a glucose-specific system and a third system with high affinity for glucose but capable of transporting fructose in glucose's absence.
Conclusions:
- Maize root tips possess intricate hexose uptake systems with distinct specificities and affinities.
- Evidence suggests that high and low affinity hexose uptake components may share carrier proteins.
- A simple method for determining inhibitor constants in competition experiments was proposed.
More Related Videos
Related Concept Videos
02:34Water and Mineral Acquisition
Specialized tissues in plant roots have evolved to capture water, minerals, and some ions from the soil. Roots exhibit a variety of branching patterns that facilitate this process. The outermost root cells have specialized structures called root hairs that increase the root surface, thus increasing soil contact. Water can passively cross into roots, as the concentration of water in the soil is higher than that of the root tissue. Minerals, in contrast, are actively transported into root cells.
02:12Short-distance Transport of Resources
Short-distance transport refers to transport that occurs over a distance of just 2-3 cells, crossing the plasma membrane in the process. Small uncharged molecules, such as oxygen, carbon dioxide, and water, can diffuse across the plasma membrane on their own. In contrast, ions and larger molecules require the assistance of transport proteins due to their charge or size. Transport across membranes also occurs within individual cells, playing a variety of essential roles for the plant as a whole.
01:30Membrane Proteins
Plasma membranes have integral transmembrane proteins involved in facilitated transport. These proteins are collectively referred to as transport proteins, and they function as either channels for the material or as carriers themselves. Channel proteins have hydrophilic domains exposed to the intracellular and extracellular fluids and a hydrophilic channel through their core that provides a hydrated opening for solutes to pass through the membrane layers. Passage through the channel allows...
02:02Phloem and Sugar Transport
Like many living organisms, plants have tissues that specialize in specific plant functions. For example, shoots are well adapted to rapid growth, while roots are structured to acquire resources efficiently. However, sugar production is primarily restricted to the photosynthetic cells that reside in the leaves of angiosperm plants. Sugar and other resources are transported from photosynthetic tissues to other specialized tissues by a process called translocation.
02:03Xylem and Transpiration-driven Transport of Resources
The xylem of vascular plants distributes water and dissolved minerals that are taken up by the roots to the rest of the plant. The cells that transport xylem sap are dead upon maturity, and the movement of xylem sap is a passive process.
02:04Regulation of Transpiration by Stomata
During photosynthesis, plants acquire the necessary carbon dioxide and release the produced oxygen back into the atmosphere. Openings in the epidermis of plant leaves is the site of this exchange of gasses. A single opening is called a stoma—derived from the Greek word for “mouth.” Stomata open and close in response to a variety of environmental cues.