Nitric oxide participates in waterlogging tolerance through enhanced adventitious root formation in the euhalophyte Suaeda salsa

The interactions of NO and other signalling molecules contribute to adventitious root formation in many plant species. To our knowledge, the role of NO in the adventitious root formation of plants subjected to waterlogging are as yet unknown. Populations of Suaeda salsa L., a C-3 euhalophytic plant, from inland saline sites develop several adventitious roots in response to waterlogging. The NO donor sodium nitroprusside (SNP) and the NO scavenger 2-(4-carboxyphenyl)-4,4,5,5-tetramethyl-imidazoline-1-1-oxyl-3-oxide (cPTIO) were applied to S. salsa seedlings to examine the effects of NO on flooding tolerance and its possible mechanism. SNP alleviated growth inhibition and increased adventitious root formation, endogenous NO levels and adventitious root cell integrity in S. salsa subjected to waterlogging. These SNP-mediated effects were prevented by the extra application of cPTIO. SNP treatment decreased nitrate reductase activity but increased nitric oxide synthase (NOS) activity in adventitious roots. These results suggest that in S. salsa, NO participates in waterlogging tolerance by enhancing adventitious root formation and that NO generation is associated with the NOS-associated pathway.