A rice jacalin‐related mannose‐binding lectin gene, OsJRL, enhances Escherichia coli viability under high salinity stress and improves salinity tolerance of rice

Abstract Salinity, which is one of the most common abiotic stresses, may severely affect plant productivity and quality. Although plant lectins are thought to play important roles in plant defense signaling during pathogen attack, little is known about the contribution of plant lectins to stress resistance. We cloned and functionally characterized a rice jacalin‐related mannose‐binding lectin gene, Os JRL , from rice ‘Nipponbare’. We analyzed the expression patterns of Os JRL under various stress conditions in rice. Furthermore, we overexpressed Os JRL in Escherichia coli and rice. The cDNA of Os JRL contained a 438 bp open reading frame, which encodes a polypeptide of 145 amino acids. Os JRL was localized in the nucleus and cytoplasm. Real time PCR analyses revealed that Os JRL expression showed tissue specificity in rice and was upregulated under diverse stresses, namely salt, drought, cold, heat and abscisic acid treatments. Overexpression of Os JRL in E. coli enhanced cell viability and dramatically improved tolerance of high salinity. Overexpression of Os JRL in rice also enhanced salinity tolerance and increased the expression levels of a number of stress‐related genes, including three LEA (late embryogenesis abundant proteins) genes ( Os LEA 19a , Os LEA 23 and Os LEA 24 ), three Na + transporter genes ( Os HKT 1;3 , Os HKT 1;4 and Os HKT 1;5 ) and two DREB genes ( Os DREB 1A and Os DREB 2B ). Based on these results, we suggest that Os JRL plays an important role in cell protection and stress signal transduction.