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 LsAux/IAA 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 Arabidopsis Aux/IAAs, which is also supported by exon-intron structure, consensus motifs, and domain compositions. Transcriptome data suggested that most of the LsIAA genes were expressed in all tissues, whereas some of them were preferentially expressed in specific tissues. Analysis of cis-acting elements indicated the LsIAA 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 LsIAA genes in high-temperature conditions.