miR-252 targeting temperature receptor <i>CcTRPM</i> to mediate the transition from summer-form to winter-form of <i>Cacopsylla chinensis</i>.

Abstract

Temperature determines the geographical distribution of organisms and affects the outbreak and damage of pests. Insects seasonal polyphenism is a successful strategy adopted by some species to adapt the changeable external environment. <i>Cacopsylla chinensis</i> (Yang & Li) showed two seasonal morphotypes, summer-form and winter-form, with significant differences in morphological characteristics. Low temperature is the key environmental factor to induce its transition from summer-form to winter-form. However, the detailed molecular mechanism remains unknown. Here, we firstly confirmed that low temperature of 10 °C induced the transition from summer-form to winter-form by affecting the cuticle thickness and chitin content. Subsequently, we demonstrated that <i>CcTRPM</i> functions as a temperature receptor to regulate this transition. In addition, miR-252 was identified to mediate the expression of <i>CcTRPM</i> to involve in this morphological transition. Finally, we found <i>CcTre1</i> and <i>CcCHS1</i>, two rate-limiting enzymes of insect chitin biosyntheis, act as the critical down-stream signal of <i>CcTRPM</i> in mediating this behavioral transition. Taken together, our results revealed that a signal transduction cascade mediates the seasonal polyphenism in <i>C. chinensis</i>. These findings not only lay a solid foundation for fully clarifying the ecological adaptation mechanism of <i>C. chinensis</i> outbreak, but also broaden our understanding about insect polymorphism.