The NADPH oxidase OsRbohA increases salt tolerance by modulating K^(+)homeostasis in rice

摘要

Rice(Oryza sativa L.)is a staple cereal for more than two thirds of the world's population.Soil salinity severely limits rice growth,development,and grain yield.It is desirable to elucidate the mechanism of rice's salt-stress response.As the major source of H_(2)O_(2),NADPH oxidase(Rboh)is believed to be involved in salt-stress tolerance.However,the function and mechanism of rice Rboh in salt stress response remain unclear.In this study,we found that the expression of OsRbohA was up-regulated by NaCl treatment in the shoots and roots of rice seedlings.Knockout of OsRbohA reduced the tolerance of rice to salt stress.Knockout of OsRbohA blocked NaCl-induced increases of NADPH activity and H_(2)O_(2)content in roots.OsRboh A knockout inhibited root growth and disrupted K^(+)homeostasis by reducing the expression of K^(+)transporters and channel-associated genes(OsGORK,OsAKT1,OsHAK1,and OsHAK5)in roots under NaCl treatment.Under NaCl treatment,OsRbohA knockout also reduced subcellular K^(+)contents of the plasma membrane and soluble fraction.Overexpression of OsRbohA increased the expression of K^(+)transporters and channel-associated genes and reduced the loss of K^(+)ions in roots.These results indicate that OsRboh A-mediated H_(2)O_(2)accumulation modulates K^(+)homeostasis,thereby increasing salt tolerance in rice.