Close linkage of eye color genes in Tribolium castaneum.

Abstract

N the course of linkage studies involving several new mutations affecting eye I pigmentation in the flour beetle, Tribolium castaneum, it became apparent that while being nonallelic to each other and to previously reported eye mutants they were not randomly distributed in the genome. In fact, of the nine eye mutant loci thus far reported, six occur as colsely linked members of three gene pairs. It is the purpose of this report to present these new linkage relationships in T. castaneum and to discuss the nonrandom distribution of these genes in terms of their apparent locational-functional relationships. MATERIALS AND METHODS Six nonallelic eye color mutations or gene loci in Tribolium castaneum were involved in the present study. A brief description along with their original citation follows: 1. pearl, p-autosomal recessive discovered in the Chicago Wild Type Stock (PARK 1937). Pupal and adult eyes are devoid of the normal black pigment and thus have a crystalline or pearlwhite appearance. Black pigment in the ocular diaphragm causes the peripheral ommatidia to appear black (WOLSKY and M BARTLETT and BELL 1966). 3. ring, rg-sex-linked recessive found in the Purdue Wild Type Foundation Population. Eye color is very similar to the ivory and pearl phenotypes in that the light or white center of the eye is circled by a darker marginal ring. (YAMADA 1962). 4. rose, rs-sex-linked recessive derived from the Purdue Wild Type Foundation Population. Not allelic to ring or red (LASLEY 1960), but resembles the red phenotype in that the central portion of the normally black compound eye has a reddish-pink color. The rose phenotype in old adults darkens toward wild type. (REYNOLDS 1964.). 5. maroon, m-autosomal recessive discovered in an irradiated subpopulation of the Pu-due Wild Type Foundation. Eye color of pupae and young adults is maroon or dark red. The pigmentation darkens with age so that by 10 days after eclosion the maroon phenotype overlaps wild type. (EDDLEMAN 1962; EDDLEMAN and HUDSON 1965). 6. ruby, rb-autosomal recessive, nonallelic to maroon, but in the same linkage group. Bicolored eye has reddish-brown central portion which darkens slightly with age but remains distinguishable from wild type. Discovered in a wild population collected from a feed storage bin at Southern Illinois University, Carbondale, Illinois (DEWEES 1963, 1965).