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THE ACTION OF THE PLANT GROWTH HORMONE.
1William G. Kerckhoff Laboratories of the Biological Sciences, California Institute of Technology, Pasadena.
The Journal of General Physiology
|October 30, 2009
Summary
Plant growth substance stimulates coleoptile elongation by increasing respiration, but only in the presence of oxygen. High concentrations inhibit both growth and respiration.
Area of Science:
- Plant biology
- Biochemistry
Background:
- Plant growth substances, like auxins, are crucial for plant development.
- Cellular respiration provides the energy necessary for biological processes, including growth.
Purpose of the Study:
- To investigate the relationship between plant growth substances and cellular respiration in Avena coleoptile elongation.
- To determine the role of oxygen and specific inhibitors in growth substance-induced responses.
Main Methods:
- Avena coleoptile sections were exposed to solutions containing growth substances.
- Elongation was measured under varying conditions, including the absence of oxygen and presence of inhibitors like KCN and phenylurethane.
- Respiration rates were measured in response to different concentrations of growth substance.
Main Results:
- Growth substance induced significant elongation of coleoptile sections.
- Elongation was dependent on oxygen and inhibited by KCN and phenylurethane.
- Growth substance increased respiration at growth-promoting concentrations but inhibited it at high concentrations.
- Inhibitor concentrations that blocked respiration also blocked growth.
Conclusions:
- The increase in cellular respiration stimulated by growth substance appears to be essential for its growth-promoting effects.
- Oxygen is required for growth substance-mediated elongation.
- High concentrations of growth substance may disrupt cellular energy production, leading to growth inhibition.
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