Identification, phylogenetic analysis, and expression patterns of the SAUR gene family in loquat (Eriobotrya japonica)

Small auxin-up RNAs (SAURs) are the most frequent and primary auxin responsive genes, and they are commonly used as early auxin-responsive markers. Until now, no SAUR gene has been identified in Eriobotrya plants. In this study, we used Arabidopsis SAUR sequences as a query to search against the loquat genome sequence. In total, we obtained 57 SAUR genes in loquat, hereafter referred to as Eriobotrya japonica SAUR (EjSAUR) genes, which ranged from 267 to 735 bp in the coding sequence with predicted proteins of 88-244 aa. A total of 47 EjSAUR genes were distributed on 11 chromosomes of the loquat genome. Based on their physical positions, 80.9% (38 of 47) of the EjSAUR genes were clustered together on the loquat chromosomes, suggesting that tandem duplicate genes might be the major mechanism for the expansion of this family. The expression analysis displayed high expression divergence among the different organs, which suggested that EjSAUR genes may play an important role in different organs. These results laid a foundation for the functional validation of EjSAUR genes in Eriobotrya plants.