Gene Characterization and Protein Expression Analysis of LsARF2 in Lettuce (Lactuca sativa L.) Under High Temperature

In this study, our objective is to investigate the gene characteristics of LsARF2, an auxin response factor in leaf lettuce, and analyze how its protein expression responds to high temperature. To achieve this, we cloned the LsARF2 gene and utilized subcellular localization and yeast one-hybrid assays to determine its subcellular location and transcriptional activity. Subsequently, Western blot analysis was employed to track the protein expression pattern of LsARF2. The findings unveiled that the coding sequence of the LsARF2 gene spans 2196 base pairs, encoding 731 amino acids. Although LsARF2 was found localized in the cell nucleus, it demonstrated no transcriptional activation activity. Remarkably, the protein expression of LsARF2 exhibited a noticeable downward trend when subjected to elevated temperatures. Our research underscores the substantial impact of elevated temperatures on the protein expression of LsARF2 in leaf lettuce. The responsiveness of LsARF2 protein expression to high-temperature stress suggests its pivotal role in bolting. Further investigation through transgenic methods will be essential to conclusively elucidate its precise function. Additionally, following exogenous hormone treatment, the shifting expression pattern of LsARF2 implies its potential responsiveness to both GA3 and IAA. Moreover, it exerts an influence on the floral development of lettuce.