Fig. 4

Phenotype of double-flowered gentian mutant and spatial expression analysis of MADS-box genes. a Typical floral phenotypes of single flower cv. Alta (upper panels) and double-flowered mutant (lower panels). Bar = 2 cm. b qRT-PCR analysis of floral MADS-box genes in single-flowered cultivar (WT) and double-flowered mutant. Total RNAs were isolated from each whorl organ of floral buds at flower developmental stage 3 as defined by Nakatsuka et al. [58]. Values are the average of four biological replicates ± standard deviation. White bar indicates single-flowered gentian cv. Alta. Black bar indicates double-flowered mutant. ** and ND indicate significant difference (P < 0.01) and no significant difference, respectively (Student’s t-test)