外源NO对蒜薹薹苞膨大及膜质过氧化的影响

Influence of Exogenous Nitric Oxide on Enlargement of Garlic Scape and Membrane Lipid Peroxidation

薹苞膨大是蒜薹采后衰老的标志,严重影响其商品价值和食用价值。本实验用0.1、0.2、0.3、0.4mmol/L的外源NO供体亚硝基铁氰化钠(sodium nitroprusside,SNP)、0.1mmol/L亚硝酸钠(NaNO2)和0.1mmol/L的铁氰化钾(K3Fe(CN)6)溶液分别浸泡蒜薹基部3h后,晾干并暗藏于4℃条件下,定期测定薹苞直径以及抗氧化酶活性等指标。结果表明:在冷藏过程中,SNP处理抑制了薹苞逐渐膨大、薹茎基部H2O2含量、相对膜透性逐渐上升和基部POD活性的提高;SNP处理提高了SOD、CAT、抗坏血酸过氧化物酶(APX)和顶部POD活性。与对照相比,不同浓度SNP处理能显著抑制薹苞直径的膨大及薹茎基部H2O2含量的增加。其中0.1mmol/LSNP处理效果最显著。NaNO2和K3Fe(CN)6处理各指标变化和对照相比没有显著差异。由此得出:适宜浓度的外源NO能够抑制蒜薹薹苞膨大,这种抑制作用可能与抑制基部H2O2含量的增加有关。

The diameter of garlic bulbet is seemed as the aging index of postharvest garlic scape and the redistribution of cell contents affects seriously the edible value of garlic scape. In this study, the basal garlic scape was treated with various concentrations （0.1,0.2,0.3,0.4 mmol/L） of sodium nitroprusside （SNP）, 0.1 mmol/L sodium nitrite and 0.1 mmol/L potassium ferricyanide for three hours, respectively, dried and then stored at 4 ℃. During the storage of garlic scape, the diameter of garlic bulbet and activities of related antioxidant enzymes were subjected to regular determination. The results showed that compared to control, the diameter enlargement of garlic bulbet and increases of content of hydrogen peroxide, activity of peroxidase （POD） and cell membrane permeability in the basal garlic scape were inhibited by treatment of different concentrations of SNP, but the activities of superoxide dismutase （SOD）, catalase （CAT） and ascorbate peroxidase （APX） in garlic scape, and POD in apical garlic scape were increased by treatment of different concentrations of SNP in the storage process. Compared to the control （the garlic scape sample whose basal was soaked in distilled water for 3 h）, different concentrations of SNP could effectively restrain the diameter enlargement of garlic bulbet and the content increase of hydrogen peroxide. 0.1 mmol/L SNP treatment presented the most remarkable effect （p 〈 0.05）. No significant difference was found in diameter of garlic bulbet and activities of related antioxidant enzymes between 0.1 mmol/L sodium nitrite or 0. 1 mmol/L potassium ferricyanide-treated garlic scape and the control. Based on these, we concluded that exogenous nitric oxide can inhibit the diameter enlargement of garlic bulbet, and this effect may be related to inhibiting the content increase of hydrogen peroxide in the basal of garlic scape.