Abstract
Conditions influencing the opening of the bean (Phaseolus vulgaris L.) and cotton (Gossypium hirsutum L.) hypocotyl hook were defined. Such hooks were shown to undergo geotropic curvature; orientation of the hook with respect to gravity greatly affected the observed opening. Cotton and bean hooks behaved exactly opposite in regard to the presence of the cotyledons and apical bud. The cotton hook required the cotyledons for opening, but the corresponding tissue slowed or inhibited opening of the bean hook. With cotton, lower hypocotyl and root tissues stimulated hook opening, but with bean, the tissues below the hook section had little effect. Kinetin and gibberellic acid both modified hook opening in light and dark; the former was inhibitory and the latter was stimulatory. Indoleacetic acid, at concentrations above 10−5 M, caused pronounced hook closing in red light but not in the dark. These effects were generally the same with both plants. In opening of the cotton hook, the cotyledons were not necessary as a light receptor tissue. None of the growth substances tested were able to substitute completely for the cotton cotyledon. Coumarin was a pronounced inhibitor of opening of the cotton hook, and this response was expressed to such a degree as to cause hook closure with bean tissue. Reduced oxygen levels inhibited hook opening in bean. Oxygen was required in processes subsequent to the light reaction, but not for the photochemical process.
Full text
PDF
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Ikuma H., Thimann K. V. Analysis of Germination Processes of Lettuce Seed by Means of Temperature and Anaerobiosis. Plant Physiol. 1964 Sep;39(5):756–767. doi: 10.1104/pp.39.5.756. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Kang B. G., Yocum C. S., Burg S. P., Ray P. M. Ethylene and carbon dioxide: mediation of hypocotyl hook-opening response. Science. 1967 May 19;156(3777):958–959. doi: 10.1126/science.156.3777.958. [DOI] [PubMed] [Google Scholar]
- Klein W. H., Withrow R. B., Elstad V. B. Response of the Hypocotyl Hook of Bean Seedlings to Radiant Energy and Other Factors. Plant Physiol. 1956 Jul;31(4):289–294. doi: 10.1104/pp.31.4.289. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Thimann K. V., Bonner W. D. Inhibition of Plant Growth by Protoanemonin and Coumarin, and Its Prevention by Bal. Proc Natl Acad Sci U S A. 1949 Jun;35(6):272–276. doi: 10.1073/pnas.35.6.272. [DOI] [PMC free article] [PubMed] [Google Scholar]