Small but big player: the important role of microRNAs in legume crops.

Legumes are essential components of global cropping systems due to their nutritional value and contribution to sustainable agriculture. Among the regulatory molecules, small RNAs (sRNAs), particularly microRNAs (miRNAs), play crucial roles in plant development and in responses to biotic and abiotic stresses. miRNAs regulate genes involved in diverse developmental processes, including nodule formation, which is fundamental for the nitrogen-fixing symbiosis that characterizes legumes. Functional studies have demonstrated that miRNAs are key modulators of plant defense, contributing to resistance against pathogens and environmental challenges. Moreover, miRNAs also participate in cross-kingdom communication, such as plant-bacteria interactions, influencing symbiotic efficiency. Advances in molecular biology have enabled the manipulation of miRNAs and their targets for crop improvement. Current approaches include the design of artificial miRNAs (amiRNA), modulation of miRNA expression through miRNA-encoded peptides, genome editing of non-coding genes using CRISPR/Cas9, and the application of RNA interference (RNAi) technology. Together, these strategies highlight the potential of miRNA-based tools in plant biotechnology. A deeper understanding of the molecular mechanisms governing miRNA-mediated gene silencing will provide powerful resources for optimizing legume productivity and resilience within sustainable agricultural systems.