UC San Diego

Drought-induced crop reduction challenges food security among the most vulnerable human populations. One of the strategies to address this challenge is to develop drought-resistant crops. It requires a comprehensive understanding of the genes and molecular and cellular mechanisms activated by drought. Dehydrated plants produce the stress hormone abscisic acid (ABA). Accumulation of ABA in guard cells triggers stomatal closure that is mediated by the activation of sucrose non-fermenting 1-related kinases 2 (SnRK2s). Activated SnRK2-type kinases cause ABA-induced gene expression mediated by basic-domain leucine-zipper (bZIP)-type transcription factors. In this study, we applied TurboID to label and purify Arabidopsis thaliana guard cell nuclear proteomes, as well as nuclear proteins that interact specifically with this class of transcription factors. Here, we report that TurboID is indeed suitable for labeling and purifying guard cell nuclear proteomes, including protein-specific complex members. Another goal was to confirm the findings reported by a former member of our laboratory. We retransformed the Arabidopsis wildtype line with an artificial microRNA (amiRNA) to silence two basic helix-loop-helix (bHLH) transcription factors, candidates for regulating ABA responses in roots. Root growth assays demonstrated significantly reduced primary root growth in amiRNA mutants compared to Col-0, which is consistent with previous findings. Further investigations of which genes are regulated by these ABA-responsive transcription factors will be an important step toward a better understanding of the natural resistance mechanisms of plants in response to abiotic stressors and ultimately bring us closer to the development of drought-resistant crops.