Research Projects

‘The tiny seed knew that in order to grow it needed to be dropped in dirt, covered in darkness and struggle to reach the light’- this is an inspirational proverb with real meaning. Light is an important environmental cue that regulates seed germination and early seedling development. The timing of seedling emergence from underneath the soil is crucial as proper establishment of seedlings is key to future plant yields. Phytohormone Abscisic acid (ABA) inhibits early seedling development under stress and unfavourable growth conditions. Several light signaling intermediates interact with the ABA signaling components to modulate development. The bZIP transcription factor ABI5 forms the point of convergence between the and ABA signaling pathways regulating early seedling development. Several labs around the world including ours have identified light signaling intermediates like HY5, PIFs, COP1 and BBX proteins, that regulate ABI5 transcription or stability. Recently, we reported that two B-box containing microproteins BBX30/miP1b and BBX31/miP1a together with ABI5 promote ABA mediated seedling growth arrest (Singh and Datta, New Phytologist, 2023). Our results indicated that the microproteins interact with ABI5 and prevent its degradation. However, the mechanism of ABI5 degradation and the possible role of light signaling components in destabilizing ABI5 is less understood. Our preliminary results suggest that the two WD-40 domain proteins RUP1 and RUP2, previously identified as negative regulators of UV-B signaling, inhibit ABA mediated post-germination seedling arrest. rup1, rup2 and rup1rup2 double mutant are hypersensitive to ABA during germination and post-germination development. ABA can lower the transcript level of RUP1 and RUP2 during early seedling development. We also have early evidence suggesting that ABI5 can physically interact with RUP1 and RUP2. In this project, we intend to characterize the role of RUP1, RUP2 in regulating ABA-mediated seedling growth arrest. This would involve study of the transcriptional regulation of the RUP genes by light and ABA signal transducers like HY5 and ABI5. Furthermore, we intend to investigate if the turnover of ABI5 is mediated by the interacting RUP proteins. Knowledge gained from this study can be utilized in developing strategies to confer abiotic stress tolerance leading to better seedling establishment and higher agricultural yields. Since RUP proteins are UV-B regulated, this project can provide a handle to regulate seed germination and post-germination development as per suitability of environmental conditions perhaps using UV light. The RUP proteins are ubiquitous in nature, which means that the outcomes from this study can also provide leads to generate resources and strategies to combat abiotic stress conditions in crop plants.