CHARACTERIZATION OF SlMCA2, A NOVEL TYPE I METACASPASE IN SOLANUM LYCOPERSICUM AND ITS IMPLICATIONS IN PROGRAMMED CELL DEATH

Abstract

Programmed cell death (PCD) is an indispensible process in plant and animal systems that serves to eliminate cells and/or tissues and recycle nutrients from these tissues to the rest of the organism. In animals, PCD is referred to as apoptosis and is performed by caspases, a family of aspartate-specific cysteine proteinases that serve to perceive the cell death signal and execute the cell death phenotype. In 2000, Uren et al. discovered a new family of cysteine proteinases in plants called metacaspases – distant arginine/lysine-specific relatives of animal caspases – thought to be involved in plant PCD. The goal of this study was to correlate SlMCA2 expression with PCD in tomato. Polyclonal antibodies were obtained against the Type I metacaspase SlMCA2 in Solanum lycopersicum and used for Western blot analyses. BY-2 cell biolistics and in-situ hybridization were used to investigate where SlMCA2 protein and mRNA accumulate in various tissues. Results produced were replicated a minimum of three times and correlate SlMCA2 to PCD, but not initiation of PCD.