Rice ULTRAPETALA1 Regulates Developmental Reprogramming to Promote Resilience to Salinity Stress

Rice, one of the most agronomically important crops, has been challenged by high salinity that 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. In this study, we have investigated the role of rice trithorax group factor ULTRAPETALA ( OsULT1 ) that orchestrates rice development and stress response. A genome-wide chromatin immunoprecipitation analysis revealed enrichment of OsULT1 to transcription factors and 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 also showed OsULT1 occupancy under control and salt stress. OsULT1 transcriptionally regulates these loci during stress response by modulating H3K4me3 and H3K27me3 modifications. OsULT1 overexpression ( OsULT1-3 ) causes developmental changes in rice with enhanced plant height, increase in basal internode length; robust root architecture; increase in tiller and panicle numbers. Moreover, OsULT1-3 showed salinity tolerance with enhanced seed germination, reduced ROS content, low Na + /K + ratio in shoot and root tissue, and enhanced post-stress recovery. Collectively, our results indicate that ULT1 regulates different developmental pathways for better protection and adaptation against environmental stress.