Manipulation of hemoglobin expression affects Arabidopsis shoot organogenesis

► Arabidopsis hemoglobin (GLB1, 2, and 3) are expressed during in vitro shoot organogenesis. ► GLB2 inhibits organogenesis while over-expression of GLB1 or GLB2 enhances shoot formation. ► Hemoglobins affect cytokinin response and differentially regulate Type-A and -B ARRs. ► Over-expression of GLB1 and 2 induces shoot formation at low levels of cytokinins.