The role of phytochromes in cadmium stress responses in tomato

It is well known that phytochromes mediate a wide range of photomorphogenic processes in plants. In addition, many studies have demonstrated the involvement of phytochromes as part of abiotic stress signaling responses. However, little is known about cadmium (Cd) stress regulation by phytochromes. Thus, in this study, we used the phyA (far red-insensitive; fri), phyB1 (temporary red-insensitive; tri) and phyB2 (phyB2) tomato (Solanum lycopersicum L.) mutants to investigate the roles of these three phytochromes on Cd stress responses. The plants were grown over a 21-d period in the presence of Cd. We evaluated plant growth, Cd and chlorophyll content and anatomical changes in the leaves. The results indicated that all genotypes were affected by Cd and showed reduced growth of the shoots and roots, as well as reduced chlorophyll content. The accumulation of Cd was similar for all genotypes, and a higher Cd content was found in roots. Anatomical analysis of the vascular bundles revealed that fri and tri seem to be more disrupted by Cd. Overall, these results indicate that phytochromes do not determine Cd stress tolerance in tomato plants.