Distinct Roles of Two UDP-N-Acetylglucosamine Pyrophosphorylase Genes in Chitin Biosynthesis and Molting of Oedaleus asiaticus (Orthoptera: Acrididae)

UDP-N-acetylglucosamine pyrophosphorylase (UAP) is an essential enzyme in the insect chitin biosynthesis pathway; however, little is known regarding its molecular functions in <i>Oedaleus asiaticus</i> Bey-Bienko (Orthoptera: Acrididae). Here, two <i>UAP</i> genes, <i>OaUAP1</i> and <i>OaUAP2</i>, were identified and characterized in <i>O. asiaticus</i>. The effects of exogenous treatments, including the molting hormone 20-hydroxyecdysone (20E) and the chitin biosynthesis inhibitor validamycin (VA), were assessed on chitin synthesis. Sequence analyses have shown that the cDNA and deduced amino acid sequences of <i>O. asiaticus</i> share over 90% identity with UAPs in <i>Locusta migratoria</i>. <i>OaUAP1</i> and <i>OaUAP2</i> are widely expressed in many tissues and developmental stages but exhibit different expression patterns: <i>OaUAP1</i> shows higher expression in the epidermis and fifth-instar nymphs, while <i>OaUAP2</i> is primarily expressed in the fat body and in the fifth-instar nymphs and adults. The functional analysis of two <i>OaUAPs</i> revealed that <i>OaUAP2</i> was crucial in molting; moreover, its implication also exists in other biosynthetic processes since nymphs maintained normal growth and development. Both <i>OaUAP</i> expressions were upregulated by 20E and downregulated by VA in the chitin biosynthesis pathway. Our findings provide a vital molecular insight into the chitin biosynthesis pathway of <i>O. asiaticus</i> and lay a solid foundation for developing environmentally safe biological insecticides.