ULTRAPETALA 1 regulates the growth and development of rice plants to promote resilience to salinity stress

Rice, one of the most important agronomically crops, when challenged by high salinity affects its growth at the seedling stage and reproductive phase. Thus, investigating the intricate molecular mechanisms that regulate its developmental process throughout its life cycle is essential for better stress resilience. We have investigated the role of rice trithorax group factor ULTRAPETALA1 (OsULT1) that orchestrates rice development and stress response. A genome-wide chromatin immunoprecipitation analysis revealed OsULT1 enrichment at transcription regulators, oxidative stress signaling, ROS scavengers, and K+ uptake transporters, during salinity stress. Interestingly, loci associated with root development, plant height, inflorescence development, panicles, spikelet numbers, and seed development showed OsULT1 occupancy under control and salt stress. Expression of these genes was regulated by chromatin modifications such as H3K4me3 and H3K27me3. Further, DNA binding analysis showed OsULT1 binding at AP2/ERF core motif A/GCCGAC during salinity stress. OsULT1 overexpression causes developmental changes with enhanced plant height, increase in basal internode length, robust root architecture, and increase in tiller and panicle numbers. Moreover, OsULT1OE showed salinity tolerance with enhanced seed germination, reduced ROS content, low Na+/K+ ratio in shoot and root tissue, and improved post-stress recovery. Collectively, our results indicate that ULT1 regulates different plant developmental pathways for better protection and adaptation against environmental stress. •Expression of Rice ULTRAPETALA1 increases during salinity stress.•OsULT1 occupancy indicates enrichment of stress loci at oxidative stress, ROS signalling, ion channels, and TFs.•OsULT1 overexpression leads to increase in plant height, basal internodal length and robust root architecture.•OsULT1 overexpression plants showed resilience against salinity stress.•OsULT1 regulates developmental and stress response genes expression by modulating chromatin modifiers.