Under heavy metal stress: genomic characterization and expression profiles of miRNA families in Phaseolus vulgaris.

Increasingd abiotic stress conditions and factors globally affect important crop plants such as common beans (Phaseolus vulgaris L.) on an agronomic scale. Among abiotic stressors, heavy metal stress is among the most impactful and challenging for plants. Heavy metals such as Cd, As, Ni, and Pb significantly reduce crop yields and negatively affect plant survival. Plants develop various defense and adaptation mechanisms to cope with stress conditions, one of which is miRNA-mediated regulation. This study aimed to investigate the genomic organization and structural characteristics of four miRNA families (miR167, miR396, miR398, and miR408), which are thought to play a critical role in abiotic stress responses, and to determine two genotype-specific expression profiles of miRNAs and target genes under heavy metal stress. RT-qPCR analyses were performed on tolerant (G68) and sensitive (G53) genotypes exposed to four different heavy metal stresses for 7 days to understand their distinct stress responses and adaptation strategies. The analyses revealed that miRNA-target gene interactions in G68 and G53 genotypes yielded different results, both genotype-dependent and genotype-independent. The results of this study indicate that further research is needed to confirm the protein-level changes in target genes and the physical interactions between proteins. These findings provide additional insights into the mechanisms of heavy metal tolerance in beans.