CRISPR-Cas systems for enhancing chilling tolerance in rice: recent advances and future prospects

Rice (Oryza sativa L.) is an important staple crop in global food security and highly vulnerable to chilling stress, which greatly affects growth, development, and yield. The conventional breeding methods for enhancing chilling tolerance face numerous problems due to the polygenic nature of chilling tolerance and genetic complexities. The present review discusses the use of CRISPR-Cas genome editing technologies as an accurate and effective approach to increasing chilling tolerance in rice. We initially describe the physiological effects of chilling stress, such as membrane fluidity impairment, inhibition of photosynthesis, nutrient imbalance, and oxidative injury, and summarize major molecular pathways and genetic materials involved in chilling tolerance. The review then outlines the recent developments in CRISPR-Cas systems, including the modes of delivery (Agrobacterium-mediated transformation, protoplast transfection, and ribonucleoprotein techniques) and how they apply to rice genome editing. The precise examination of CRISPR-based functional genomics has shown that cold-responsive genes (OsMYB30, OsWRKY76, OsAnn3, OsPRP1, and OsKASI-2) are selectively manipulated, thus contributing to a clearer understanding of their functional roles in stress signaling, membrane stability, and antioxidant defense. Moreover, we also discuss recent CRISPR strategies, including multiplex editing, transcriptional reprogramming (CRISPRa/i), and omics-guided fine-tuning of gene networks. Synthesizing latest advancements, current review establishes a conceptual framework to overcome translational challenges in CRISPR-mediated improvement of complex traits in oilseed crops, through integrating the pivotal aspects of genotype-specific delivery, multi-gene network design, field validation, and the evolving regulatory landscape. The review concludes with a reflection of gaps in research and future opportunities, with a discussion on how integrated CRISPR technologies can be used to enhance the development of climate-resistant rice varieties.