Overexpression of the CmJAZ1-like gene delays flowering in Chrysanthemum morifolium

Chrysanthemum (Chrysanthemum morifolium) is one of the four major cut-flower plants worldwide and possesses both high ornamental value and cultural connotation. As most chrysanthemum varieties flower in autumn, it is costly to achieve annual production. JAZ genes in the TIFY family are core components of the jasmonic acid (JA) signaling pathway; in addition to playing a pivotal role in plant responses to defense, they are also widely implicated in regulating plant development processes. Here, we characterized the TIFY family gene CmJAZ1-like from the chrysanthemum cultivar ‘Jinba’. CmJAZ1-like localizes in the nucleus and has no transcriptional activity in yeast. Tissue expression pattern analysis indicated that CmJAZ1-like was most active in the root and shoot apex. Overexpressing CmJAZ1-like with Jas domain deletion in chrysanthemum resulted in late flowering. RNA-Seq analysis of the overexpression lines revealed some differentially expressed genes (DEGs) involved in flowering, such as the homologs of the flowering integrators FT and SOC1, an FUL homolog involved in flower meristem identity, AP2 domain-containing transcription factors, MADS box genes, and autonomous pathway-related genes. Based on KEGG pathway enrichment analysis, the differentially transcribed genes were enriched in carbohydrate metabolic and fatty acid-related pathways, which are notable for their role in flowering in plants. This study preliminarily verified the function of CmJAZ1-like in chrysanthemum flowering, and the results can be used in molecular breeding programs aimed at flowering time regulation of chrysanthemum.