Expression of a rice gene OsNOA1 re-establishes nitric oxide synthesis and stress-related gene expression for salt tolerance in Arabidopsis nitric oxide-associated 1 mutant Atnoa1

Nitric oxide (NO) has been indicated in regulating a wide-spectrum of plant developmental events and stress responses. An Arabidopsis gene AtNOA1 encodes a NO-associated protein, which plays a role in salt tolerance. We employed the knockout mutant for AtNOA1, Atnoa1 that is sensitive to salinity, as a tool to evaluate the functions of a rice homologous gene, OsNOA1.OsNOA1 transgenic expression rescued Atnoa1 in seedling development and vegetative growth under normal conditions, enhanced the salt tolerance of Atnoa1 in seed germination, seedling root growth and chlorophyll synthesis, and reduced Na+/K+ ratio in Atnoa1; NO relative content assay implicates that NO synthesis was re-established via OsNOA1 expression in Atnoa1; Northern blot and Semi-Q RT-PCR assays demonstrate that salt tolerance-related gene expression was re-established as well via OsNOA1 expression in Atnoa1.Our data indicate that the re-establishment of NO synthesis and salt tolerance-related gene expression by OsNOA1 expression may account for the restoration of Atnoa1 in terms of developmental and salt tolerance phenotypes. All the above results point to a notion that OsNOA1 may play similar roles as AtNOA1, and NO involvement in salt tolerance may be ascribed to its regulation of salt tolerance-related gene expression.