Involvement of nitrate reductase in auxin-induced NO synthesis

It is well known for a long time, that nitric oxide (NO) functions in variable physiological and developmental processes in plants, however the source of this signaling molecule in the diverse plant responses is very obscure. 1 Although existance of nitric oxide sythase (NOS) in plants is still questionable, LNMMA (N-G-monomethyl-L- arginine)-sensitive NO generation was observed in different plant species. 2,3 In addition, nitrate reductase (NR) is confirmed to have a major role as source of NO. 4,5 This multifaced molecule acts also in auxin-induced lateral root (LR) formation, since exogenous auxin enhanced NO levels in regions of Arabidopsis LR initiatives. Our results pointed out the involvement of nitrate reductase enzyme in auxin-induced NO formation. In this addendum, we speculate on auxin-induced NO production in lateral root primordial formation.