Studies on the scavenging function of hygrohpytes to methane induced in the severely reduced conditions

湿地中的湿生植物植被降低了严重还原条件下产生的土壤甲烷浓度。土壤甲烷浓度降低的顺序为万寿菊（E）、田菁（S）>芦苇（R）>水稻（I）>东北野生稻（M）。根际土壤甲烷生成活性大小顺序为I、M、R>无湿生植物> E、S，根际土壤甲烷氧化活性在无湿生植物的土壤中略高，在有不同种类湿生植物的土壤中差异不大。在模拟实验中（气体系统中甲烷浓度为70%，液体系统中甲烷浓度为1%），在低氧浓度下水培的植物比在有氧条件下预培养的植物发育出溶生通气组织，并通过其地上部释放出更大量的甲烷。植物在气态系统中释放甲烷的能力明显高于液态系统 ...更多信息 根系释放大气氧的顺序为M> R> I> S> E，过氧化物酶和过氧化氢对α-萘胺的氧化能力顺序为E> R，S> M> I，且根尖部分氧化能力较高。根际Eh升高的顺序为E、S> R> M、I，E、S的表皮和皮层质外体中检测到高浓度的H2O2，严重还原的土壤溶液中检测到高浓度的Fe ^2+。在体外实验中，H_2O_2和Fe ^<2 +>共存条件下，溶解甲烷的浓度显著降低。通过添加已知为羟基自由基清除剂的甘露醇来否定甲烷浓度的降低也表明由芬顿反应产生的羟基自由基直接清除根质外体中的甲烷。结果表明，在添加Fe ^<2 +>的溶液中，湿生植物尤其是E和S显著降低了甲烷浓度.综上所述，E和S不仅可以通过其根系的强氧化力抑制根际土壤甲烷的产生活性，而且还具有直接在其质外体中释放甲烷的功能。这些发现为新植物的创造提供了新的和重要的数据，耐受严重还原条件的植物，和具有高度抑制植物释放甲烷能力的植物。并阐述了蔬菜、水果和牧草中黄酮类化合物和酚类化合物的抗氧化功能。少

Vegetation of hygrophytes in wetland decreases the concentration of soil methane produced in the severely reduced conditions. The order of the decreasing power of the concentration of soil methande was erect bur marigold (E), sesbania (S) >reed (R) >rice (I) >Manchurian wild rice (M). The order of activity of methane production in rhizosphere soil was I,M,R>without hygrophytes>E,S.The activity of methane oxidation in rhizosphere soil was a little higher in the soil without hygrophtes and was hardly different among the soils overgrown with different kind of hygrophytes. In the model experiments (methane concentration in gas system was 70%, and that in liquid system was 1%), plants cultured previously in hydroponically under the low oxygen concentration developed lysigenous aerenchyma and emitted larger amounts of methane through their shoot than those precultured in aerobic conditions. The emission ability of methane through plants was considerably higher in gas system than in liquid sy … More stem, and the order was M> I,R,E> S.The order of release of atmospheric oxygen from roots was M> R> I> S> E.The order of oxidizing power of alpha-naphthylamine mediated both by peroxidase and hydrogen peroxide was E> R,S> M> I,and this power was higher in the tip portions of roots. The order of raising power of rhizosphere Eh was E,S> R> M,I.High concentration of hydrogen peroxide was detected in the apoplast of epidermis and cortex of E and S.High concentration of Fe^<2+> was detected in the solution of the severely reduced Soil. In vitro experiments, the dissolved methane was significantly decreased in the co-existing conditions of H_2O_2 and Fe^<2+>. Negation of the decrease in methane concentration by the addition of mannitol which is known as the scavenger of hydroxyl radical also suggests the direct scavenging of methane in the apoplast of roots with hydroxyl radical which is produced by Fenton reaction. Hygrophytes especially E and S considerably decreased the methane concentration in the solution added Fe^<2+>. In conclusion, E and S not only can suppress the production activity of methane in rhizosphere soil by their strong oxidizing power of roots but also possess the function to scavenge methane directly in their apoplast. These findings offer the novel and important data for the creation of new plants i.e., plants tolerant to the severely reduced conditions, and plants having highly suppressive ability of methane emission through plants. The antioxidative function of flavonoids and phenolic compounds in vegetables, fruits, and grasses was also elucidated. Less