Genome-wide identification, expression profiling, and functional analysis of sugar transporter family genes in Diaphorina citri.

Sugar transporters (STs) are important proteins responsible for the movement of sugar through the cell membrane and play pivotal roles in the growth, development, and osmoregulation of phloem-feeding hemipterans. However, information about STs in the Asian citrus psyllid (ACP), Diaphorina citri Kuwayama (Hemiptera: Liviidae), remains unknown. In this study, a total of 61 STs were identified according to the genome and transcriptome analysis of D. citri. All the ST genes have complete open reading frames (ORFs), and most of them have 12 transmembrane regions. Chromosome localization and phylogenetic tree analysis found several expansions occurred in the ST gene family. The developmental stage- and tissue-specific expression patterns of STs were characterized. Besides, feeding with different sugars and host plants altered the expression level of the top ten expressed genes in the midgut of D. citri. Furthermore, RNAi against DcST16, DcST38, DcST52, and DcST56 induced significant mortality in D. citri adults. Moreover, the swollen abdomen phenotype was observed in the adults with siRNA-DcST56 treatment. These findings lay the foundation for further function analyses of STs in D. citri.