Inflated calyx syndrome (ICS), a morphological novelty in Solanaceae, is controlled by the expression of a MADS-box gene, MPF2-like (WSA206), in the floral tissues of Withania. By exploring the rich diversity of calyx morphology in the related taxa, it is shown that the MPF2-like gene duplication in Withaninae has provided an important playground for new evolutionary innovations. Sub- (neo)-functionalization and gene loss were very important in conjunction with positive Darwinian selection in the evolution of ICS. The expression divergence in MPF2-like genes due to reciprocal loss of...