Mechanical Wounding Induces Rapid RNA-Degrading Activity Mediated by the S-like Ribonuclease PvRNS2 in Common Bean

Common bean (Phaseolus vulgaris) is an important crop for human nutrition due to its high protein content and capacity to fix atmospheric nitrogen. However, crop productivity is frequently compromised by biotic and abiotic stresses, among which wounding represents a highly prevalent challenge. Thus, understanding early molecular and biochemical responses to tissue damage is essential for improving plant stress resilience. We have investigated the effects of mechanical wounding on nucleic acid-degrading activities in the common bean. Mechanical wounding of leaves rapidly induced ribonuclease activity, whereas nuclease activities remained unchanged. Gel activity assays revealed a predominant ribonuclease, which was identified by proteomic analysis as PvRNS2, a member of the S-like RNase T2 family. This wound-induced ribonuclease was inhibited more strongly by nucleoside di- and triphosphate than by the corresponding nucleoside monophosphate. The increase in ribonuclease activity correlated with a rapid and transient induction of PvRNS2 expression, which peaked at 2 h after injury (600-fold increase). A similar transcriptional response was observed in radicles subjected to mechanical damage (55-fold increase), indicating that PvRNS2 responds to wounding in both aerial and subterranean tissues. In contrast, the wound-induced increase in PvRNS2 expression was not associated with a coordinated upregulation of genes encoding enzymes involved in downstream nucleotide degradation. Together, these results identify PvRNS2 as a major contributor to wound-induced RNA turnover in the common bean and support the involvement of RNA metabolism in early responses to mechanical damage. The participation of ribonucleases in the wound response of economically vital legumes remains unexplored. This work addresses this knowledge gap, establishing a new framework for understanding nucleic acid degradation during legume defense.