Burr marigold (Bidens tripartita L.) roots directly and immediately scavenge rhizosphere methane with highly exuded hydrogen peroxide via a rhizosphere Fenton reaction

Abstract

The major factors controlling the soil methane (CH4) concentration and CH4 emissions of various plant (mainly wetland) species were identified. Five plant species (Oryza sativa, Zizania latifolia, Phragmites australis, Sesbania cannabina, and Bidens tripartita) were separately cultivated under the flooded soil conditions. The direct CH4 scavenging potential of B. tripartita roots was also measured in conjunction with in vitro CH4 scavenging experiments using H2O2 and several transition metal ions. CH4 emissions from the soil-cultivated plants did not depend on the maximum CH4 emission potential for each plant species but on the soil CH4 concentrations, which were positively correlated with the CH4 production potential of the soil and negatively correlated with soil Eh values. Bidens tripartita roots possessed the highest increasing soil Eh potential and a direct, immediate, and continuous CH4 scavenging potential via the Fenton reaction using a considerably high concentration of root apoplastic H2O2 and rhizosphere Fe2+. Bidens tripartita presented the highest soil Eh ascending potential. The in vitro experiments suggested the involvement of・OH/FeIVO2+ via the newly termed rhizosphere Fenton reaction as a strong destructive power for CH4. To our knowledge, this is the first report on direct CH4 scavenging by high H2O2-exuding plant roots.