Limited aerenchyma reduces oxygen diffusion and methane emission in paddy

Greenhouse gasses (GHG) emission from the agricultural lands is a serious threat to the environment. Plants such as rice (Oryza sativa L.) that are cultivated in submerged conditions (paddy field) contribute up to 19% of CH₄ emission from agricultural lands. Such plants have evolved lysigenous aerenchyma in their root system which facilitates the exchange of O₂ and GHG between aerial parts of plant and rhizosphere. Currently, the regulation of GHG and O₂ via aerenchyma formation is poorly understood in plants, especially in rice. Here, a reverse genetic approach was employed to reduce the aerenchyma formation by analyzing two mutants i.e., oslsd1.1-m12 and oslsd1.1-m51 generated by Tos17 and T-DNA insertion. The wild-type (WT) and the mutants were grown in paddy (flooded), non-paddy and hydroponic system to assess phenotypic traits including O₂ diffusion, GHG emission and aerenchyma formation. The mutants exhibited significant reductions in several morphophysiological traits including 20-60% aerenchyma formation at various distances from the root apex, 25% root development, 50% diffusion of O₂ and 27-36% emission of methane (CH₄) as compared to WT. The differential effects of the oslsd1.1 mutants in aerenchyma-mediated CH₄ mitigation were also evident in the diversity of (pmoA, mcrA) methanotrophs in the rhizosphere. Our results indicate the novel pathway in which reduced aerenchyma in rice is responsible for the mitigation of CH₄, diffusion of O₂ and the root growth in rice. Limited aerenchyma mediated approach to mitigate GHG specially CH₄ mitigation in agriculture is helpful technique for sustainable development.