Letters to the Editor: Does C4 photosynthesis occur in wheat seeds?

In 2016, Rangan et al. reported on “New evidence for grain specific C₄ photosynthesis in wheat,” but later that year Busch and Farquhar responded with “Poor evidence for C₄ photosynthesis in the wheat grain.” Now these two groups continue their arguments for and against wheat seed C₄ photosynthesis, in a quartet of Letters to the Editor. Is the issue settled? No, but the publication of these letters provides insights into how data are interpreted differently, and how scientific disagreements can be conducted in a open and respectful manner. This is a great topic and collection for students to read and discuss. Plant Physiol. 10.1104/pp.17.00837