Rice (Oryza sativa L.) plants are simultaneously encountered by environmental stressors, most importantly salinity stress. Salinity is the major hurdle that can negatively impact growth and crop yield. Understanding the salt stress and its associated complex trait mechanisms for enhancing salt tolerance in rice plants would ensure future food security. The main aim of this review is to provide insights and impacts of molecular-physiological responses, biochemical alterations, and plant hormonal signal transduction pathways in rice under saline stress. Furthermore, the review highlights the emerging breakthrough in multi-omics and computational biology in identifying the saline stress-responsive candidate genes and transcription factors (TFs). In addition, the review also summarizes the biotechnological tools, genetic engineering, breeding, and agricultural practicing factors that can be implemented to realize the bottlenecks and opportunities to enhance salt tolerance and develop salinity tolerant rice varieties. Future studies pinpointed the augmentation of powerful tools to dissect the salinity stress-related novel players, reveal in-depth mechanisms and ways to incorporate the available literature, and recent advancements to throw more light on salinity responsive transduction pathways in plants. Particularly, this review unravels the whole picture of salinity stress tolerance in rice by expanding knowledge that focuses on molecular aspects.

Key message: A parthenocarpic fruit mutant of prickly pear was isolated, revealing the role of GAs in parthenocarpic fruit development which is controlled by the GID-GA20ox/GA2ox genetic system modulating GA biosynthesis/regulation. We explored the intricate dynamics of parthenocarpic fruit development in prickly pear Opuntia ficus-indica (Cactaceae) through the investigation of fruits of the Beer Sheva1 (BS1) a parthenocarpic mutant and its revertant non-parthenocarpic stems. BS1 fruits, characterized by parthenocarpy and enlarged unfertilized ovules, provide a unique model for investigating the regulatory mechanisms underlying fruit development in prickly pear. We hypothesized that elevated levels of gibberellins (GAs) in BS1 ovaries induce parthenocarpic fruit development. By integrating different approaches, including GA quantification and expression analysis of ovaries from BS1 and revertant flowers, we elucidated the pivotal role of biosynthetic, catabolic, and regulatory GA genes in orchestrating ovule development. Notably, our investigation revealed a complex interplay between GA biosynthesis and catabolic genes, particularly GID1, GA20ox, and GA2ox, which significantly influenced GA levels in BS1 ovaries. Quantification of endogenous GAs confirmed higher levels of bioactive GA1, GA3, and GA4 in BS1 compared to revertant ovules, indicating the central role of GAs in parthenocarpy. Furthermore, application of the GA inhibitor paclobutrazol (PBZ) to BS1 flower buds resulted in the reversion of BS1 fruits to the progenitor phenotype containing viable seeds, thereby validating the critical involvement of GAs in seed development. High-throughput RNA-sequencing analysis identified a total of 7717 differentially expressed genes (DEGs) in BS1, among them GA-related genes. Overall, our findings shed light on the complex hormonal regulatory network governing parthenocarpic fruit development in prickly pear, paving the way for future studies aiming at understanding ovule development and development of commercially desirable seedless fruits.