Functional Genomics of Sulfur Metabolism in Rice: Insights From Transgenic and MicroRNA-Based Strategies

Sulfur (S) is an essential macronutrient that plays critical roles in plant growth, redox homeostasis, stress adaptation, and immunity. In rice (Oryza sativa), sulfur deficiency is becoming increasingly common due to modern agricultural practices, yet the molecular regulation of sulfur metabolism remains incompletely understood. Recent advances in functional genomics have provided new insights into the mechanisms governing sulfur uptake, transport, assimilation, and downstream metabolic regulation. This review synthesizes current knowledge of sulfur metabolism in rice, with particular emphasis on transgenic and microRNA-based approaches. We discuss the functions of sulfate transporters, sulfur assimilation enzymes, and sulfur-containing metabolites such as glutathione in regulating sulfur homeostasis, redox balance, and stress responses. Particular attention is given to the conserved miR395 regulatory module, which coordinates sulfur assimilation and allocation through posttranscriptional regulation of ATP sulfurylase genes. Evidence from functional genomics studies demonstrates that sulfur metabolism is closely integrated with redox signaling, stress tolerance, and plant immunity. Collectively, these findings support a view of sulfur metabolism as a dynamic regulatory network rather than a linear nutrient-assimilation pathway. We further highlight key knowledge gaps, emerging research opportunities, and future directions for applying functional genomics to improve sulfur use efficiency and resilience in rice. This review provides a framework for advancing both the fundamental understanding and translational application of sulfur metabolism in sustainable rice production.