Background Chrysanthemum morifolium is one of the most economically important and popular floricultural crops in Asteraceae. Chrysanthemums have many different flower colors and shapes. However, the molecular mechanism controlling the development of chrysanthemum floral colors and shapes is still an enigma. We obtained a cut chrysanthemum variety with mutant capitula in which the ray florets became green and the inside pistils became vegetative buds, while normal capitula have many rounds of purple ray florets and few disc florets.
Results We conducted whole-transcriptome analysis of differentially expressed genes (DEGs) between the mutant and normal capitula using third-generation and second-generation sequencing techniques. We identified DEGs between the mutant and normal capitula to reveal important regulators underlying their differential development. Regulatory genes involved in the photoperiod pathway and the control of floral organ identification as well as important functional genes in the anthocyanin synthesis pathway were also identified. Therefore, a list of candidate genes for studying flower development and anthocyanin synthesis in chrysanthemums was generated. Qualitative analysis of pigments in the florets of normal and mutant capitula revealed anthocyanins were synthesized and accumulated in the florets of normal capitula, but not in the florets of mutant capitula. It was indicated that pistils may be required for anthocyanin synthesis in chrysanthemums.
Conclusions These results will help to elucidate the molecular mechanisms of floral organ development and will contribute to the development of techniques for studying flower shape and color regulation to promote breeding in chrysanthemum.