ARS | Publication request: Nitric Oxide Generated Exogenously by Donors Or Endogenously from Nitrite Reduces Ethylene Biosynthesis in 'golden Delicious' Apple Cortex Disks

Submitted to: Meeting Abstract
Publication Type: Proceedings/Symposium
Publication Acceptance Date: January 13, 2006
Publication Date: N/A

Technical Abstract: Nitric oxide ('NO) has a demonstrated role in physiological processes of many organisms. In plants, 'NO has been implicated in cell damage, active oxygen species (AOS) quenching, and a variety of wound signaling pathways including modulation of ethylene biosynthesis. The current study examines the generation of 'NO by NO2- as well as reduction of ethylene biosynthesis by `Golden Delicious¿ apple fruit cortex disks. Disks were suspended in solutions containing either S-nitrosoglutathione (GSNO), oxidized glutathione (GSSG), sodium nitroprusside (SNP), sodium ferrocyanide, or potassium nitrite (NO2-) dissolved in 0.1 M MES plus 0.01 M CaCl2 (pH 6). Following a 30 min equilibration period, vessels were sealed for an additional 30 min and sampled to measure evolved ethylene and 'NO. Treatment with solutions containing the 'NO donors GSNO and SNP reduced ethylene biosynthesis compared to treatments containing equimolar concentrations of GSSG or sodium ferrocyanide, respectively. GSSG and sodium ferrocyanide did not affect ethylene biosynthesis. Treatment with NO2- resulted in increased 'NO production and, likewise, decreased ethylene biosynthesis. Generation of 'NO increased linearly while ethylene generation decreased exponentially with increasing NO2- treatment concentration. While this evidence shows 'NO is readily generated by NO2- treatment and ethylene synthesis is reduced by 'NO / NO2- treatment, the exact nature of 'NO generation from NO2- and ethylene synthesis modulation remains to be elucidated.