Characterization of the role of SPL4 in the regulation of drought stress and trichome development in alfalfa

The impacts of climate change are expected to increase the demand for crops resistant to drought stress. Understanding how molecular mechanisms control plant response to stress is crucial to prevent losses in crop yield. Studies conducted in Medicago sativa (alfalfa) have shown that genetic modifications can induce plant mechanisms to increase stress tolerance. miR156 is a long non-codingRNA which negatively regulates gene expression at the post-transcriptional level. Trichomes are physical structures present on plant tissues that can aid plants in transpiration reduction. We studied the role of SQUAMOSA PROMOTER BINDING PROTEIN-LIKE 4 (SPL4), a target of miR156, in alfalfa’s response to drought and trichome development. We found that SPL4 regulates trichome development and drought stress response. Transgenic alfalfa plants with RNAi-silenced SPL4 (SPL4-RNAi) have an increased trichome density under both control and drought conditions. In response to 14 days of withholding water, SPL4-RNAi plants had an increased root length, an increased water content in roots, shoots and leaves, and an increased water potential in the leaves when compared to wild-type plants. This study shows SPL4 has a role in trichome development and drought stress response, making it a potential target for modification to improve plant tolerance to drought stress.