Phytochrome-controlled Hydrogen Ion Excretion by Avena Coleoptiles
1Department of Biology, Franklin and Marshall College, Lancaster, Pennsylvania 17604.
Plant Physiology
|April 1, 1977
Summary
Red light triggers proton efflux in oat coleoptiles, a process vital for plant growth. This response, enhanced by auxin, is sensitive to metabolic inhibitors and stimulants.
Area of Science:
- Plant Physiology
- Photobiology
- Molecular Biology
Background:
- Plant growth and development are regulated by light signals.
- Hormones like auxin play crucial roles in plant cell elongation.
- Proton efflux is a key mechanism in plant cell wall loosening.
Purpose of the Study:
- To investigate the effect of red light on proton efflux in Avena sativa coleoptiles.
- To determine the relationship between red light, auxin, and proton efflux.
- To elucidate the metabolic pathways involved in light-induced proton transport.
Main Methods:
- Apical segments of etiolated Avena sativa L. cv. Victory coleoptiles were used.
- Proton efflux was measured under red light and far-red light.
- The effects of cycloheximide, carbonyl cyanide m-chlorophenyl hydrazone, and mannitol were assessed.
- Responses to red light and auxin, individually and in combination, were analyzed.
Main Results:
- Red light induced a far-red reversible proton efflux.
- Acidification responses were not due to respired carbon dioxide (CO2).
- Cycloheximide and carbonyl cyanide m-chlorophenyl hydrazone inhibited the red light response.
- Mannitol stimulated the red light response.
- Combined red light and auxin treatment produced a synergistic effect.
Conclusions:
- Red light perception triggers proton efflux in Avena coleoptiles.
- This process is metabolically dependent and influenced by auxin.
- The interaction between light and auxin signaling pathways is complex and synergistic.
Related Concept Videos
02:00Photoreceptors and Plant Responses to Light
Light plays a significant role in regulating the growth and development of plants. In addition to providing energy for photosynthesis, light provides other important cues to regulate a range of developmental and physiological responses in plants.
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.
01:25Cell Signaling in Plants
Plant cells communicate to coordinate their cycle of growth, flowering and fruiting, and activities in roots, shoots, and leaves in response to the changing environmental conditions. Plant signaling is distinct from animal signaling. Plants primarily utilize enzyme-linked receptors, whereas the largest class of cell-surface receptors in animals are G-protein coupled receptors (GPCRs). Unlike animals, receptor tyrosine kinases are rare in plants. Instead, plants have a diverse class of...
02:45Biological Clocks and Seasonal Responses
The circadian—or biological—clock is an intrinsic, timekeeping, molecular mechanism that allows plants to coordinate physiological activities over 24-hour cycles called circadian rhythms. Photoperiodism is a collective term for the biological responses of plants to variations in the relative lengths of dark and light periods. The period of light-exposure is called the photoperiod.
01:56Plant Hormones
Plant hormones—or phytohormones—are chemical molecules that modulate one or more physiological processes of a plant. In animals, hormones are often produced in specific glands and circulated via the circulatory system. However, plants lack hormone-producing glands.
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.