Abstract:

Effects of nitric oxide (NO) donor sodium nitroprusside (SNP), NO specific scavenger c-PTIO and nitric oxide synthase (NOS) inhibitor L-NAME on the rooting of mung bean (Vigna radiata L.) hypocotyl cuttings were studied. The spatio-temporal changes of NO and NADPH-diaphorase in the basal part of cutting were also detected during the adventitious rooting process. The results showed that SNP significantly enhanced the adventitious rooting in the range of concentrations tested. NADPH-diaphorase activity (commonly employed as a marker for NOS) and the fluorescence of NO were respectively observed in the zone between the vascular bundles of the basal part of cuttings at 24 h and 36 h after cutting. The root primordium became discernible at 48 h after cutting in the same region, and became more elongate at 60 h. NADPH-diaphorase activity and NO fluorescence gradually increased during 48-60 h and mainly distributed in root meristem. L-NAME treatment delayed adventitious root emergency and significantly reduced the NADPH-diaphorase staining and the fluorescence of NO. The specific NO scavenger, c-PTIO, also suppressed the fluorescence and inhibited the formation of adventitious roots. These results suggest that endogenous NO appears to play a key role in the generation and development of adventitious roots, and the production of NO in this process may be catalyzed by NOS-like enzyme.

Key words: nitric oxide (NO), NADPH-diaphorase, mung bean hypocotyl cutting, adventitious root, generation, development