Plant proteases: guardians of proteome integrity and regulators of protein function.

Proteases degrade proteins that are damaged, misfolded, or no longer needed. This enables plants to repurpose their proteomes in response to environmental cues and adapt to adverse conditions. Proteases also play key roles in plant growth and development by the selective degradation of regulatory proteins. However, there is much more to proteases than just protein degradation. They can also act in a highly site-specific manner, ensuring protein maturation after subcellular targeting, regulating protein activity and function, and releasing or modulating peptide signals. Since their activity is irreversible and potentially deleterious, proteases are tightly controlled by endogenous inhibitors and other regulatory mechanisms. The reviews and research articles in this Special Issue put a timely spotlight on the fascinating diversity, function, and regulation of proteases in plants, discuss current challenges and technical developments, and provide a perspective on their use for crop protection.