Identification of miRNA Targets by AtFT Overexpression in Tobacco

The onset of flowering is regulated by complex gene networks that integrate multiple genetic cues to floral transition in plants. The highly conserved florigen FLOWERING LOCUS T (FT) functions at the core of this process. Here, we demonstrate that overexpression of Arabidopsis FT in tobacco (oxAtFT) leads to precocious flowering in a photoperiod-independent manner. Strikingly altered phenotypes such as stunted growth, increased number of axillary branches, change in leaf morphology, and elongated style were observed in oxAtFT transgenic tobacco plants. In addition, the generation time of oxAtFT tobacco was drastically reduced by 8-10 weeks. We observed defects in lateral root formation in both oxAtFT tobacco and oxFT Arabidopsis lines. Interestingly, oxAtFT tobacco displayed significant heat and drought tolerance as compared to the wild type. Through small RNA profiling, we observed the upregulation of a conserved microRNA (nta-miR393a-5p) of miR393 family that targets the TRANSPORT INHIBITOR RESPONSE 1-like (TIR1) gene. Overall, the heterologous expression of AtFT in tobacco may have potential in imparting abiotic stress tolerance in other plant species through plant biotechnology-based approaches.