Genetic breeding of silkworms: from traditional hybridization to molecular design

Sericulture is one of the great inventions of the Chinese people and has become an important cultural feature of China. As China is the long-lasting center of silk production, genetic breeding of silkworm was highly developed historically, and has formed a comprehensive system for breeding and preservation of new varieties. However, silkworm breeding reached a bottleneck recently, because most of the traditional genetic resources have been utilized and silkworm strains have become homogeneous. Meanwhile, sericulture in China meets huge challenges in the 21^st century. In recent years, with the development and rapid application of molecular biology, genomics, transgene and genome editing, silkworm genetic breeding has entered a new era. In this review, we summarize the development of silkworm genetic breeding, especially the progress and perspective of transgene and genome editing in genetic engineering of silkworms. We also discuss the future development of silkworm genetic breeding.