Silkworms' survival strategy - Discovery of a new enzyme that controls the production of plant aromas! -

Research has clarified through experiments that silkworms have acquired a strategy whereby a newly discovered enzyme excreted by them controls the biosynthesis of plant aromas so that they can feed on mulberry leaves while protecting themselves from natural enemies. The research was conducted by a group led by Professor Kenji Matsui, Hiroki Takai (a master's course student who subsequently entered the doctoral course at the Graduate School of Agricultural and Life Sciences at the University of Tokyo, and is currently a postdoctoral researcher at the National Institute of Advanced Industrial Science and Technology) and Professor Jun Kobayashi at Yamaguchi University's Graduate School of Sciences and Technology for Innovation (Agriculture), together with a group led by Professor Toru Shimada and Yukio Ishikawa at the Graduate School of Agricultural and Life Sciences at the University of Tokyo, a group led by Professor Junji Takabayashi at Kyoto University's Center for Ecological Research, a group led by Satoshi Nakamura (a chief researcher at the Japan International Research Centre for Agricultural Sciences), Associate Professor Toshiyuki Onishi and Associate Professor Hideo Dohra at Shizuoka University's Research Institute of Green Science and Technology, Professor Yooichi Kainoh at University of Tsukuba's Faculty of Life and Environmental Sciences, and Associate Professor Masayoshi Uefune at Meijo University's Faculty of Agriculture.

When an insect feeds on a plant, the plant emits "green leaf volatiles" that attract the insect's natural enemies and get them to kill it. This well-known mechanism is called plants' indirect defense.

When silkworms feed on mulberry leaves, they excrete an enzyme from a spinneret near their mouth. Because this enzyme suppresses the production of "green leaf volatiles," mulberry plants cannot easily attract parasitoid flies, which are natural enemies of silkworms.

- The research clarified that silkworms had acquired a strategy for safely feeding on mulberry leaves, whereby they use a secreted enzyme to control the biosynthesis of plant aroma and suppress the production of "green leaf volatiles," so that they will not be noticed by parasitoid flies.

- It was clarified that this enzyme is a newly discovered enzyme that was hitherto unknown, and is a specific enzyme that is found only among butterflies and moths.

The research was aided by JSPS Grants-in-aid for Scientific Research (JP26660095 and JP25282234).

The research results were published in Scientific Reports on August 9 (Thu.).


DOI: 10.1038/s41598-018-30328-6