Identification and Expression of SAUR Genes in the CAM Plant Agave

Abstract

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