AGAMOUS correlates with the semi-double flower trait in carnation

Flower type is the most valuable ornamental trait in floricultural plants, for which the ABCDE model was proposed to explain the identity of each floral organ in flowering plants. The C-class gene AGAMOUS (AG) is responsible for stamen formation and plays an essential role in the double flower phenotype. A previous study in carnation revealed that the mutation in the miR172 binding site of the A-class gene APETALA2 (AP2) leads to petal accumulation. And the expression level of AG was reduced significantly in the double flowers compared with that in the single flowers. However, there was no sequence polymorphism detected between AGs isolated from the double flowers and single flowers. Here, we performed AG analysis using single and semi-double flower carnations, and detected several mutations located in the crucial position like the MADS-box domain in the AGs of semi-double flower carnations while no changes were found at the miR172 binding site of AP2. As a result, the expression levels of AGs are reduced in the semi-double flower carnation, which could be caught by the loss function of AGs. Our data proves that AGs mutations are also associated with the semi-double flower formation in carnation, complementing the lack of research about AG-mutation-associated double flower formation in carnation.