yellow and ebony Are the Responsible Genes for the Larval Color Mutants of the Silkworm Bombyx mori

Abstract

Many larval color mutants have been obtained in the silkworm Bombyx mori. Mapping of melaninsynthesis genes on the Bombyx linkage map revealed that yellow and ebony genes were located near the chocolate (ch) and sooty (so) loci, respectively. In the ch mutants, body color of neonate larvae and the body markings of elder instar larvae are reddish brown instead of normal black. Mutations at the so locus produce smoky larvae and black pupae. F 2 linkage analyses showed that sequence polymorphisms of yellow and ebony genes perfectly cosegregated with the ch and so mutant phenotypes, respectively. Both yellow and ebony were expressed in the epidermis during the molting period when cuticular pigmentation occurred. The spatial expression pattern of yellow transcripts coincided with the larval black markings. In the ch mutants, nonsense mutations of the yellow gene were detected, whereas large deletions of the ebony ORF were detected in the so mutants. These results indicate that yellow and ebony are the responsible genes for the ch and so loci, respectively. Our findings suggest that Yellow promotes melanization, whereas Ebony inhibits melanization in Lepidoptera and that melanin-synthesis enzymes play a critical role in the lepidopteran larval color pattern.

The transcription factor Apontic-like controls diverse colouration pattern in caterpillars

“…It is noteworthy that the yellow expression coincides with the black regions and is not detected in the white striped region 31 . The weak induction of TH, DDC and Laccase 2 in the p S phenotype after moulting stages ( Supplementary Fig.…”

“…In the swallowtail butterfly P. xuthus, expressions of seven melanin-related genes, yellow, tan, ebony, DDC, TH, Laccase 2 and GTPCHI, are strongly correlated with larval eye-spot markings 3,31,[46][47][48] . Most of these expressions coincide with species-specific cuticle markings of other Papilio species, P. polytes and P. machaon 5 .…”

“…Although the Apt-like-regulated gene pathway remains unclear, the abundant expression of yellow and ebony is considered to be involved in the dorsal black stripes of the silkworm p S strain 31 . It is noteworthy that the yellow expression coincides with the black regions and is not detected in the white striped region 31 .…”

“…Turner 30 introduced four different mutations of this silkworm, Moricaud (p M ), Zebra (Ze), Multilunar (L) and quail (q), which are good models for investigating caterpillar mimicry with various patterns. We previously found that the melanin synthesis genes yellow and ebony were responsible for the silkworm colour mutants chocolate (ch) and sooty (so) loci, respectively 31 . In addition, we recently found that L resulted from the ectopic expression of Wnt1 in the epidermis 32 .…”

Two genomic regions together cause dark abdominal pigmentation in Drosophila tenebrosa

“…The yellow gene is conserved across insects (Ferguson et al, 2011) and has been implicated in the synthesis of melanic pigment in Drosophila wings, abdomen, thorax and mouthparts, as well as in certain aspects of behavior (Biessmann, 1985;Wittkopp et al, 2002a;Wittkopp et al, 2002b;Drapeau et al, 2003;Gompel et al, 2005;Prud'homme et al, 2006). yellow has also been implicated in the pigmentation of other insects, for example the silkmoth Bombyx mori and Heliconius butterflies (Futahashi et al, 2008;Hines et al, 2012). Further analyses are necessary to characterize the sites responsible for the change in expression of yellow between D. tenebrosa and D. suboccidentalis.…”