The early wilting and yellowing of leaves in response to ethylene is the main limitation affecting the vase quality of cut chrysanthemums. Therefore, leaf senescence is the most difficult problem in the post-harvest and production of chrysanthemums. Nevertheless, the molecular mechanism of ethylene on the regulation of post-harvest senescence of cut chrysanthemum leaves is still unclear. In this study, we identified an ethylene-sensitive chrysanthemum ‘FenDante,’ which showed rapid chlorophyll content decrease under ethylene treatment, resulting in leaf yellowing and wilting before flower senescence. A new generation of Illumina sequencing platform was used to identify differentially expressed genes in the leaves in response to ethylene treatment in chrysanthemum. A total of 1.04 Gb of raw reads was obtained, including 753 and 2790 differentially expressed genes at 3 h and 24 h after ethylene treatment, respectively. KEGG analysis revealed that the differentially expressed genes are mainly involved in plant hormone synthesis and signal transduction, chlorophyll metabolism, aquaporins, and reactive oxygen species. The gene expression regulatory networks in the leaves of post-harvest cut chrysanthemums in response to ethylene treatment were studied, which lays the foundation for future research on the molecular mechanisms of ethylene-mediated leaf senescence in cut chrysanthemums.

Chlorophyll is vital for photosynthesis to produce sugars and other useful biochemical products in green plants. However, the molecular effects of chlorophyll deficiency in Chrysanthemum are largely unknown. In this study, we identified a bud sport mutant chrysanthemum belonging to the variety ‘Nannong Binyun’, which has yellow branches. Plant physiological studies have shown that the yellow color is revealed due to chlorophyll loss. RNA extracts of yellow and green tissues were analyzed using high-throughput RNA-sequencing, and a total of 11,649 tissue enriched unigenes that respond to chlorophyll deficiency were identified, including 4803 unigenes upregulated in yellow tissues and 6846 unigenes in green tissues. GO analysis revealed that these tissue-enriched genes may involve in the physiological processes of chlorophyll accumulation and photosynthesis. In addition, many DEGs from the families of AP2-EREBP, bHLH, MYB, and FAR1 that are associated with plant development and stress response were detected. Our study found that most of the genes from the GRAS family were downregulated in yellow leaves, indicating their putative roles in stem cell maintenance and possible contribution to leaf size determination.