Rice lectin proteinOsr40c1imparts drought tolerance by modulatingOsSAM2,OsSAP8 and chromatin-associated proteins

Lectin proteins play an important role in biotic and abiotic stress responses in plants. Although the rice lectin protein, Os r40c1, has been reported to be regulated by drought stress, the mechanism of its drought tolerance activity has not been studied so far. In this study, it has been depicted that expression of Osr40c1 gene correlates with the drought tolerance potential of various rice cultivars. Transgenic rice plants overexpressing Osr40c1 were significantly more tolerant to drought stress over the wild-type plants. Furthermore, ectopic expression of the Osr40c1 gene in tobacco yielded a similar result. Interestingly, the protein displayed a nucleo-cytoplasmic localization and was found to interact with a number of drought-responsive proteins like Os SAM2, Os SAP8, Os MNB1B, and Os H4. Fascinatingly, silencing of each of these protein partners led to drought susceptibility in the otherwise tolerant Os r40c1 expressing transgenic tobacco lines indicating that these partners were crucial for the Os r40c1-mediated drought tolerance in planta . Together, the present investigation delineated the novel role of Os r40c1 protein in imparting drought tolerance by regulating the chromatin proteins, Os MNB1B and Os H4, which presumably enables Os SAP8 to induce downstream gene expression. In addition, its interaction with Os SAM2 might induce polyamine biosynthesis thus further improving drought tolerance in plants. Highlights A rice lectin protein, Osr 40c1, plays a crucial role in imparting drought stress tolerance in plants by modulating Os SAM2 as well as the transcriptional regulators Os SAP8, Os MNB1B and Os H4.