FaTEDT1L of Octoploid Cultivated Strawberry Functions as a Transcriptional Activator and Enhances Abiotic Stress Tolerance in Transgenic Arabidopsis .

Plants may encounter abiotic stresses, such as drought, flooding, salinity, and extreme temperatures, thereby negatively affecting their growth, development, and reproduction. In order to enhance their tolerance to such stresses, plants have developed intricate signaling networks that regulate stress-responsive gene expression. For example, Arabidopsis Enhanced Drought Tolerance1/HOMEODOMAIN GLABROUS 11 ( AtEDT1/HDG11 ), one of the transcription factor genes from the group IV of homeodomain-leucine zipper (HD-ZIP) gene family, has been shown to increase drought tolerance in various transgenic plants. However, the underlying molecular mechanisms of enhanced stress tolerance remain unclear. In this study, we identified a homologous gene related to AtEDT1/HDG11 , named FaTEDT1L , from the transcriptome sequencing database of cultivated strawberry. Phylogenetic analysis revealed the close relationship of FaTEDT1L with AtEDT1/HDG11, which is one of the group IV members of the HD-ZIP gene family. Yeast one-hybrid analysis showed that FaTEDT1L functions as a transcriptional activator. Transgenic Arabidopsis plants overexpressing FaTEDT1L under the control of the cauliflower mosaic virus (CaMV) 35S promoter exhibited significantly enhanced tolerance to osmotic stress (both drought and salinity) when compared to the wild-type (WT) plants. Under osmotic stress, the average root length was 3.63 ± 0.83 cm, 4.20 ± 1.03 cm, and 4.60 ± 1.14 cm for WT, 35S::FaTEDT1L T ₂ #3 , and 35S:: FaTEDT1L T ₂ #5 , respectively. Substantially increased root length in 35S::FaTEDT1L T ₂ #3 and 35S::FaTEDT1L T ₂ #5 was noted when compared to the WT. In addition, the average water loss rates were 64%, 57.1%, and 55.6% for WT, 35S::FaTEDT1L T2 #3 , and 35S::FaTEDT1L T ₂ #5 , respectively, after drought treatment, indicating a significant decrease in water loss rate of 35S:: FaTEDT1L T ₂ #3 and 35S::FaTEDT1L T ₂ #5 is a critical factor in enhancing plant drought resistance. These findings thus highlight the crucial role of FaTEDT1L in mitigating drought and salt stresses and regulating plant osmotic stress tolerance. Altogether, FaTEDT1L shows its potential usage as a candidate gene for strawberry breeding in improving crop resilience and increasing agricultural productivity under adverse environmental conditions.