Polyamines and Root Formation in Mung Bean Hypocotyl Cuttings

Publisher Website
Google Scholar
Abstract
The effect of several polyamines (putrescine spermidine and spermine), their precursors (L-arginine and L-ornithine) and some analogs and metabolic inhibitors (L-canavanine, L-canaline and methylglyoxal-bis [guanylhydrazone]) on root formation were studied in mung bean (V. radiata [L.] Wilczek) hypocotyl cuttings. Exogenously applied polyamines did not promote adventitous root formation. Rooting was inhibited by L-canavanine and L-canaline and this inhibition was reversed by the corresponding amino acids L-arginine and L-ornithine. Methylglyoxal-bis (guanylhydrazone), an inhibitor of S-adenosylmethionine decarboxylase and polyamine biosynthesis, also inhibited root formation. All compounds at concentrations of > 10-4 M completely inhibited natural root formation, whereas at < 10-5 M only the IBA-induced root formation was inhibited. IBA-induced root formation was accompanied by a considerable increase in polyamine levels, > 2-fold of the control. Whereas senescing (unrooted) cuttings evinced a rapid decline in polyamine content during 48 h IBA treatment resulted in elevated levels of putrescine and increased putrescine to spermidine ratio. The changes in polyamines were dependent on IBA concentration and were organ-specific.