Root barriers to radial O2 loss restrict CH4 entry and plant-mediated emissions.

Root barriers to radial O2 loss in rice restrict plant-mediated CH4 emissions, with emissions positively correlated to whole-root ROL across genotypes.

• Why it matters: Understanding the traits that control methane emissions from rice is crucial for managing greenhouse gases, but the specific root features influencing gas exchange are not well understood.
• What they did: Sixteen rice genotypes with contrasting root traits, including a mutant with a weak ROL barrier, were grown hydroponically; researchers measured CH4 emissions, whole-root ROL, root anatomy, and morphology.
• The result: Emissions varied widely and were linked to whole-root ROL, while root anatomy and size did not explain differences; the ROL barrier constrains both O2 loss and CH4 entry, making whole-root ROL a key trait in emission regulation.