Lignification of tomato (Solanum lycopersicum) pericarp tissue during blossom-end rot development

Abstract Blossom-end rot is a physiological disorder causing significant losses in the tomato industry each year. Accumulation of reactive oxygen species has been established as a key characteristic of blossom-end rot development. An increase in peroxidase activity and lignin precursor content are also associated with blossom-end rot symptoms, leading to the hypothesis that lignification may be occurring during blossom-end rot development. To investigate the potential involvement of lignification, hydrogen peroxide content, catalase activity, and peroxidase activity were measured in the top, bottom, and blossom-end rot affected tissue of blossom-end rot affected fruit, and the top and bottom of healthy fruit. Lignin was assayed using histochemical staining, autofluorescence, and thioglycolic acid degradation methods. Hydrogen peroxide content was increased in blossom-end rot affected and blossom-end rot adjacent tissues compared to healthy fruit and the top of blossom-end rot affected fruit. Catalase activity was significantly reduced and ferulic acid peroxidase activity was increased in the blossom-end rot affected and unaffected tissue at the bottom of blossom-end rot affected fruit compared to the bottom of healthy fruit. Lignin analyses showed increased lignin content in blossom-end rot affected tissue compared to tissue from the bottom of healthy fruit. These results show that lignification occurs during blossom-end rot development, likely through a peroxidase-mediated pathway.