The BTB-ZF gene Bm-mamo regulates pigmentation in silkworm caterpillars

Abstract

The color pattern of insects is one of the most dazzling adaptive evolutionary phenotypes. However, the molecular regulation of this color pattern is not fully understood. In this study, we found that the transcription factor Bm-mamo is responsible for black dilute ( bd ) allele mutations in the silkworm. Bm-mamo belongs to the BTB zinc finger family and is orthologous to mamo in Drosophila melanogaster . This gene has a conserved function in gamete production in Drosophila and silkworms and evolved a pleiotropic function in the regulation of color patterns in caterpillars. We found that Bm-mamo can comprehensively regulate the expression of related pigment synthesis and cuticular protein genes to form color patterns. This indicates that insects have a genetic basis for coordinate regulation of the structure and shape of the cuticle, as well as color patterns. This genetic basis provides the possibility for constructing the complex appearances of some insects. This study provides new insight into the regulation of color patterns. The color patterns of insects are highly exquisite and significantly divergent. The metabolism of pigments is the material basis for insect coloration. However, the cuticle of insects plays an important role as a scaffold for carrying pigment particles. Cuticular proteins are some of the main components of the cuticle. This study showed that a BTB-ZF family transcription factor protein, Bm-mamo, can comprehensively regulate melanin synthesis and the expression of multiple cuticular protein genes. Hence, insects have a genetic basis for integrated control of cuticle and color pattern construction, which enables them to produce complex appearances.