Cucurbit Genetics Cooperative Report 6:13 (article
A Second Long Hypocotyl Mutant at the lh Locus
M. Koornneef and B. J. van der Knaap
Department of Genetics, Agricultural University, Wageningen, The Netherlands (first author); Deruiterzonen B.V., Bleiswijk, The Netherlands (second author)
Monogenic mutants having an elongated hypocotyl when grown in white light have been described for several loci in plants like Arabidopsis thaliana (2) and tomato (3). Compared to the wild type, those mutants show an altered inhibition spectrum which is locus-specific when grown under light of restricted spectral regions. Some of those genes apparently regulate the presence of phytochrome in the hypocotyl. Since cucumber is frequently used for the study of seedling physiology, the presence of such hypocotyl mutants in this species would be very useful for photophysiological research.
Van der Knaap and de Ruiter (1) found such a mutant in the progeny of one of their megurk plants irradiated by a 137 Cs-y source. That monogenic recessive mutant was found to be allelic to a similar mutant described by Robinson and Shail (4) as the F1 of both mutants also had a long hypocotyl. Some characteristics of the original mutant, such as reduced fertility and strongly-reduced growth of the higher internodes, were not due to pleiotropic effects of the 1h gene because they segregated independently from that gene in F2 progenies derived from a cross of that mutant and the cultivar, Stereo.
Preliminary experiments indicate that the mutant reacts to light in a manner similar to hypocotyl mutants of other species, e.g. continuous red light no longer inhibits hypocotyl elongation. A more detailed physiological characterization of the mutant is in progress.
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- Koornneef, M., E. Rolff and C. J. P. Spruit. 1980. Genetic control of light-inhibited hypocotyl elongation in Arabidopsis thaliana Heynh. Z. Pflanzenphysiol. 100:147160.
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- Robinson, R. W., and J. W. Shail. 1981. A cucumber mutant with increased hypocotyl and internode length. Cucurbit Genetics Coop. Rpt. 4:1920.