Genetic variation in methane emissions in rice alters seasonal profiles of methanogenic microbial communities in anaerobic soils

Authors: Barnaby, Jinyoung; FERNANDEZ-BACA, CRISTINA - U.S. DEPARTMENT OF STATE; MCCLUNG, ANNA; Rivers, Adam; Roberts, Daniel

Submitted to: Food and Drug Administration (FDA) Science Forum
Publication Type: Abstract Only
Publication Acceptance Date: 8/31/2021
Publication Date: 8/31/2021
Citation: Barnaby, J.Y., Fernandez-Baca, C.P., McClung, A.M. 2021. Genetic variation in methane emissions in rice alters seasonal profiles of methanogenic microbial communities in anaerobic soils. Food and Drug Administration (FDA) Science Forum. https://jam-2021.virtualpostersession.org/

Interpretive Summary:

Technical Abstract: Rice paddies are one of the major global agricultural sources of anthropogenic methane emissions. The warm, water-logged soil found in rice paddies is an ideal condition for methanogenesis. The methanogens in the soil utilize organic matter from rice root exudates and fertilizers in the soil to produce methane. Methane emissions from rice paddies can be mitigated through reduced irrigation practices, but this can increase nitrous oxide emissions, another important greenhouse gas, and decrease grain yield. Key to meeting these challenges is to breed low methane emitting rice cultivars. However, evaluating genetic variation in methane emissions is challenging as measuring gas flux is time-consuming and labor intensive. Rice genetics and the plant-associated soil microbiome are huge untapped resources for addressing this problem. Our research has shown that low and high methane emitting genotypes had contrasting seasonal profiles of two microbial groups which contribute to the biogeochemical methane cycle in soil. Methanogens, methane-producing bacteria, were low at the early developmental stage, and gradually increased in abundance for the rest of growing season in the low CH4 emitters while they stayed highly abundant throughout the whole growing season in the high CH4 emitters. In contrast, methanotrophs, methane-oxidizing bacteria, were high at the early stage, then gradually decreased in abundance over the growing season in the low CH4 emitters while they remained low for the whole season in the high CH4 emitters. Our research demonstrated that the profile of particular methanogens and methanotrophs identified in this study varies corresponding to the amounts of methane flux driven by rice cultivars. Our results hold promise to use the soil microbial profile as a potential phenotyping tool to select for rice breeding lines having low methane emissions.