Genome landscape of the universal stress protein gene family in lettuce and expression profile in response to heat stress.

backgroundThe Universal Stress Protein (USP) family plays a pivotal role in modulating growth, development as well as abiotic and biotic stress responses in plants. Lettuce (Lactuca sativa), a highly consumed vegetable crop, is highly sensitive to high temperatures, resulting in physiological disorders that limit its overall yield, quality, and marketability. Considering the importance of thermoresilience for crop productivity, the functional landscape of the USP gene family remains unexplored in the lettuce genome.

resultsIn this study, we conducted comprehensive bioinformatic analyses covering phylogenetic relationships, exon-intron structure, conserved motifs, cis-regulatory elements, synteny, protein phosphorylation and glycosylation and identified thirty-three USP genes in the lettuce genome. We showed that domain architecture played a significant role in the functional diversification of USP genes, which holds similarities for all USPs in plant. Phylogenetic analysis grouped USP into four distinct classes. Our synteny analysis provided evidence of a higher conservation of USP members in dicot genomes than in monocot genomes, suggesting an early divergence of USP from monocot groups. Expression profiling of the identified USP genes based on RNA-seq data revealed that most genes were highly expressed across multiple tissues, indicating their potential role in multiple developmental processes. Furthermore, gene expression analysis showed that LsUSP genes were induced in response to high temperatures. Thus, our results revealed the high transcriptional responsiveness of USP genes to heat stress in lettuce.

conclusionOverall, this study provides an in-depth characterization of the lettuce USP family, integrating gene structure, phylogenetic relationships, cis-elements, synteny, conserved domain architecture, and gene expression analyses. Our findings suggest that LsUSPs may be involved in thermotolerance in lettuce, highlighting their potential as genetic resource for breeding heat-tolerance lettuce.