Gene Nomenclature Rules for the Cucurbitaceae

admin

Cucurbit Genetics Cooperative Report 1:41-42 (article 38) 1978

R. W. Robinson
New York Agricultural Experiment Station, Geneva, NY 14456

The Pickling Cucumber Improvement Committee voted unanimously on October 18, 1977, to adopt the proposed (1) nomenclature rules for genes of the Cucurbitaceae. Discussion at the annual PCIC meeting brought out the following considerations:

  • Rule 1 states that the names of gene should describe a characteristic feature of the mutant in a minimum number of words. It was emphasized that the name chosen for a mutant should be as descriptive as possible, for descriptive names are a mnemonic aid and encourage use of the mutant by researchers with an interest in its phenotype. Names such as that of the chlorophyll deficient (cd) gene of the cucumber are not as descriptive as, for example, pale lethal (pl); both cd and pl are lethal, but the name of only one of the mutants describes this feature of its phenotype. Other chlorophyll deficient mutants of the cucumber, such as variegated virescent (vvi), have good descriptive names since they characterize the chlorophyll pattern and its change during development.
  • Rule 2 states that gene symbols should be a minimum number of italicized Roman characters. There is no need to use more than 3 symbols for a gene of any cucurbit at this time. Although short names and a minimum number of letters in the symbol are generally preferable for simplicity, the name should not be so short that it is not sufficiently descriptive. As examples of names and symbols that are overly abbreviated, we have the dark (D) gene and the light (l) gene of Cucurbita pepo; longer gene names and symbols would be desirable, to inform that D affects stem color and l fruit color.
  • Rule 3 states that the name and symbol for a gene should pertain to the mutant allele, and the normal or wild type allele should be given the symbol “+”. To conserve gene symbols, this rule was not made retroactive. Genes which were previously named after the normal rather than the mutant phenotype were not changed, but gene names and symbols proposed in the future must related to the mutant to be acceptable. Some cucurbit genes were named in the past only on the basis of F1 data or speculation.
  • These gene symbols were not accepted, of course, and rule 4 requires that statistically valid segregation data be provided for each proposed gene.
  • Mimic series are permitted, but not required, by rule 5. Examples of such series, where different mutants with similar phenotypes have the same symbol followed by distinguishing numbers, are the ms-1 and ms-2; pm-1, pm-2, and pm-3; and yc-1 and yc-2 genes of the cucumber.
  • Rule 6 states that multiple alleles should have the same symbol, followed by a different letter or number superscript. A multiple allelic locus has been proposed for fruit skin color in the watermelon, with g conditioning light green skin, gs striped green skin, and g+ dark green skin. Alleles of the same locus with identical phenotypes preferably should be given the same symbol. However, if there is reason to symbolize apparent re-occurrences of a previous mutation.
  • Rule 7 states that they should have the same symbol as the original mutant with distinguishing numbers or letters in parentheses or superscripts.
  • Rule 8 states that modifying genes may either have distinctive names and symbols or they may have a symbol for an appropriate name, such as intensifier, suppressor, or inhibitor, followed by a hyphen and the symbol of the allele affected. Examples of the latter are the In-de and In-F genes of the cucumber. The only reason why gene symbols were revised (1) is because that symbol had previously been used for another gene.
  • Rule 9 states that priority in publication is the primary consideration for establishing the preferred symbols. A very large number of cucurbit genes were given symbols that had previously been proposed for other genes, and in many cases several different symbols were used for the same gene. All such cases were revised on the basis of priority.

Literature Cited

Robinson, R. W., H. M. Munger, T. W. Whitaker, and G. W. Bohn. 1976. Genes of the Cucurbitaceae. HortScience 11:554-568.