Genome-wide Identification and Expression Analysis of the Argonaute Gene Family in Sugar Beet (Beta vulgaris L.)

The argonaute (AGO) protein is a component of the transcription-induced silencing complex of target genes mediated by the small RNA pathway in plants, which, together with small RNAs, regulates gene expression and influences, among other processes, the formation of monoembryos and polyembryos in plants. In this work, a comprehensive systematic identification of the BvAGO gene family in the whole genome of sugar beet was carried out by utilizing the conserved domains of the AGO proteins. A total of nine BvAGO gene family members were identified, and the physicochemical properties, phylogeny, gene structure, promoter regions, and replication events of the nine family members were analyzed via bioinformatics methods. Moreover, the expression profiles of the nine genes of the AGO family in beet were analyzed in different beet tissues and verified via RT‒qPCR technology. The results revealed that these BvAGO proteins were classified into four branches with protein lengths ranging from 712 to 1142 aa, and subcellular localization predicted that four BvAGO members were located in the cytoplasm, four in the nucleus, and one in the extracellular region and that the nine genes were distributed on five chromosomes. Overall, the expression patterns of sugar beet AGO gene members and Arabidopsis thaliana AGO gene members in tissues were very similar, among which the BvAGO1, BvAGO4c, BvAGO5a, and BvAGO5b genes were highly expressed in all the tissues; these genes are hypothesized to be involved in the regulation of related single-embryo multiple-embryo development in sugar beets, and the present study provides guidance for further studies of the function of AGO proteins in sugar beets. This study provides guidance for further research on the function of the AGO protein in sugar beet.