Identification and Expression of SAUR Genes in the CAM Plant Agave

Agave species are important crassulacean acid metabolism (CAM) plants and widely cultivated in tropical areas for producing tequila spirit and fiber. The hybrid H11648 of Agave ((A. amaniensis × A. angustifolia) × A. amaniensis) is the main cultivar for fiber production in Brazil, China, and African countries. Small Auxin Up-regulated RNA (SAUR) genes have broad effect on auxin signaling-regulated plant growth and development, while only few SAUR genes have been reported in Agave species. In this study, we identified 43, 60, 24, and 21 SAUR genes with full-length coding regions in A. deserti, A. tequilana, A. H11648, and A. americana, respectively. Although phylogenetic analysis revealed that rice contained a species-specific expansion pattern of SAUR gene, no similar phenomena were observed in Agave species. The in silico expression indicated that SAUR genes had a distinct expression pattern in A. H11648 compared with other Agave species; and four SAUR genes were differentially expressed during CAM diel cycle in A. americana. Additionally, an expression analysis was conducted to estimate SAUR gene expression during different leaf developmental stages, abiotic and biotic stresses in A. H11648. Together, we first characterized the SAUR genes of Agave based on previously published transcriptome datasets and emphasized the potential functions of SAUR genes in Agave's leaf development and stress responses. The identification of which further expands our understanding on auxin signaling-regulated plant growth and development in Agave species.