Cucurbit Genetics Cooperative Report 4:19-20 (article 9) 1981
R. W. Robinson and J. W. Shail
New York State Agricultural Experiment Station, Geneva, NY 14456
A cucumber plant with a three-fold increase in hypocotyl length was found in the F2 generation after treatment of seed of ‘Lemon’ with thermal neutron radiation. Discrete segregation occurred in the F2 generation of crosses with the mutant. On the basis of F2 ratio of 33+:11 long hypocotyl, from a cross with ‘MSU 713-5’, and other data, it is concluded that a single recessive gene is involved. The symbol lh, for long hypocotyl, is proposed.
Length of the internodes as well as the hypocotyl is increased by lh (Table 1). Despite its marked effect on internode elongation, it had no apparent effect on other phytohormone-mediated development. The mutants were normal in sex expression, fruit length, leaf shape, and other characteristics.
Previously genes have been reported to reduce internode length of the cucumber, but this is the first cucumber gene reported to increase length of internode and hypocotyl. Its unique nature, ease and reliability of classification in the seedling stage, good viability and fertility, and freedom from interference with classification for other genes makes it a useful seedling marker for the cucumber.
Table 1. Length of hypocotyl and first two internodes of F2 segregants.
Length (cm) |
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Hypocotyl |
Internode 1 |
Internode 2 |
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Class |
Mean |
Range |
Mean |
Range |
Mean |
Range |
| Lh | 5.8 | 2.0-9.0 | 5.4 | 2.0-8.5 | 7.6 | 3.3-10.0 |
| lh | 16.3 | 14.5-20.0 | 16.3 | 10.0-22.0 | 12.9 | 10.0-20.0 |