摘要Soil salinity inhibits seed germination and reduces seedling survival rate,resulting in significant yield re-ductions in crops.Here,we report the identification of a polyamine oxidase,OsPAO3,conferring salt tolerance at the germination stage in rice(Oryza sativa L.),through map-based cloning approach.OsPAO3 is up-regulated under salt stress at the germination stage and highly expressed in various organs.Over-expression of OsPAO3 increases activity of polyamine oxidases,enhancing the polyamine content in seed coleoptiles.Increased polyamine may lead to the enhance of the activity of ROS-scavenging enzymes to eliminate over-accumulated H2O2 and to reduce Na+content in seed coleoptiles to maintain ion homeo-stasis and weaken Na+damage.These changes resulted in stronger salt tolerance at the germination stage in rice.Our findings not only provide a unique gene for breeding new salt-tolerant rice cultivars but also help to elucidate the mechanism of salt tolerance in rice.