The Role of Proteases in Plant Development

Proteases play key roles in plants, maintaining strict protein quality control and degrading specific sets of proteins in response to diverse environmental and developmental stimuli. Similarities and differences between the proteases expressed in different species may give valuable insights into their physiological roles and evolution. Systematic comparative analysis of the available sequenced genomes of two model organisms led to the identification of an increasing number of protease genes, giving insights about protein sequences that are conserved in the different species, and thus are likely to have common functions in them and the acquisition of new genes, elucidate issues concerning non-functionalization, neofunctionalization and subfunctionalization. The involvement of proteases in senescence and PCD was investigated. While PCD in woody tissues shows the importance of vacuole proteases in the process, the senescence in leaves demonstrate to be a slower and more ordered mechanism starting in the chloroplast where the proteases there localized become important. The light-harvesting complex of Photosystem II is very susceptible to protease attack during leaf senescence. We were able to show that a metallo-protease belonging to the FtsH family is involved on the process in vitro. Arabidopsis knockout mutants confirmed the function of FtsH6 in vivo