Cocoonase is indispensable for Lepidoptera insects breaking the sealed cocoon

Autoři: Tingting Gai aff001;  Xiaoling Tong aff001;  Minjin Han aff001;  Chunlin Li aff001;  Chunyan Fang aff001;  Yunlong Zou aff001;  Hai Hu aff001;  Hui Xiang aff002;  Zhonghuai Xiang aff001;  Cheng Lu aff001;  Fangyin Dai aff001
Působiště autorů: State Key Laboratory of Silkworm Genome Biology, Key Laboratory of Sericultural Biology and Genetic Breeding, Ministry of Agriculture and Rural Affairs, College of Biotechnology, Southwest University, Chongqing, China aff001;  Guangdong Provincial Key Laboratory of Insect Developmental Biology and Applied Technology, Institute of Insect Science and Technology, School of Life Sciences, South China Normal University, Guangzhou, China aff002
Vyšlo v časopise: Cocoonase is indispensable for Lepidoptera insects breaking the sealed cocoon. PLoS Genet 16(9): e1009004. doi:10.1371/journal.pgen.1009004
Kategorie: Research Article
doi: 10.1371/journal.pgen.1009004


Many insects spin cocoons to protect the pupae from unfavorable environments and predators. After emerging from the pupa, the moths must escape from the sealed cocoons. Previous works identified cocoonase as the active enzyme loosening the cocoon to form an escape-hatch. Here, using bioinformatics tools, we show that cocoonase is specific to Lepidoptera and that it probably existed before the occurrence of lepidopteran insects spinning cocoons. Despite differences in cocooning behavior, we further show that cocoonase evolved by purification selection in Lepidoptera and that the selection is more intense in lepidopteran insects spinning sealed cocoons. Experimentally, we applied gene editing techniques to the silkworm Bombyx mori, which spins a dense and sealed cocoon, as a model of lepidopteran insects spinning sealed cocoons. We knocked out cocoonase using the CRISPR/Cas9 system. The adults of homozygous knock-out mutants were completely formed and viable but stayed trapped and died naturally in the cocoon. This is the first experimental and phenotypic evidence that cocoonase is the determining factor for breaking the cocoon. This work led to a novel silkworm strain yielding permanently intact cocoons and provides a new strategy for controlling the pests that form cocoons.

Klíčová slova:

Animal behavior – Guide RNA – Homozygosity – Insects – Moths and butterflies – Phylogenetic analysis – Pupae – Silkworms


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