Genome-Wide Identification and Expression Analysis of the Aux/IAA Gene Family in Lettuce (Lactuca sativa L.)

The Aux/IAA proteins are key regulators of auxin signaling transduction, mediating various physiological and developmental processes in higher plants; however, little information on Aux/IAAs is known in lettuce, an economically important vegetable. In this study, a total of 29 <i>LsAux/IAA</i> genes were identified from the lettuce genome. Sequence alignment and domain analyses suggested the presence of conserved Aux/IAA subdomains (Domain I-IV) in those LsIAAs, and Phylogenetic analysis indicated that members of LsAux/IAA could be classified into 10 subgroups by their homology to <i>Arabidopsis</i> Aux/IAAs, which is also supported by exon-intron structure, consensus motifs, and domain compositions. Transcriptome data suggested that most of the <i>LsIAA</i> genes were expressed in all tissues, whereas some of them were preferentially expressed in specific tissues. Analysis of cis-acting elements indicated the <i>LsIAA</i> genes might be regulated by hormonal treatments and abiotic stresses, which was confirmed by qRT-PCR experiments. Taken together, our study provides valuable information for further investigation of the biological roles of <i>LsIAA</i> genes in high-temperature conditions.