Rice lectin protein Osr40c1 imparts drought tolerance by modulating OsSAM2, OsSAP8 and chromatin-associated proteins

Abstract

Lectin proteins play an important role in biotic and abiotic stress responses in plants. Although the rice lectin protein, Osr40c1, 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 OsSAM2, OsSAP8, OsMNB1B, and OsH4. Fascinatingly, silencing of each of these protein partners led to drought susceptibility in the otherwise tolerant Osr40c1 expressing transgenic tobacco lines indicating that these partners were crucial for the Osr40c1-mediated drought tolerance in planta. Together, the present investigation delineated the novel role of Osr40c1 protein in imparting drought tolerance by regulating the chromatin proteins, OsMNB1B and OsH4, which presumably enables OsSAP8 to induce downstream gene expression. In addition, its interaction with OsSAM2 might induce polyamine biosynthesis thus further improving drought tolerance in plants. HighlightsA rice lectin protein, Osr40c1, plays a crucial role in imparting drought stress tolerance in plants by modulating OsSAM2 as well as the transcriptional regulators OsSAP8, OsMNB1B and OsH4.