Chrysanthemums are among the world’s most popular cut flowers, with their color being a key ornamental feature. The formation of these colors can be influenced by high temperatures. However, the regulatory mechanisms that control the fading of chrysanthemum flower color under high-temperature stress remain unclear. This study investigates the impact of high temperatures on the color and biochemical responses of purple chrysanthemums. Four purple chrysanthemum varieties were exposed to both normal and elevated temperature conditions. High-temperature stress elicited distinct responses among the purple chrysanthemum varieties. ‘Zi Feng Che’ and ‘Chrystal Regal’ maintained color stability, whereas ‘Zi Hong Tuo Gui’ and ‘Zi lian’ exhibited significant color fading, particularly during early bloom stages. This fading was associated with decreased enzymatic activities, specifically of chalcone isomerase (CHI), dihydroflavonol 4-reductase (DFR), and anthocyanidin synthase (ANS), indicating a critical period of color development under heat stress. Additionally, the color fading of ‘Zi Lian’ was closely related to the increased activity of the peroxidase (POD) and polyphenol oxidase (PPO). Conversely, a reduction in β-glucosidase (βG) activity may contribute significantly to the color steadfastness of ‘Zi Feng Che’. The genes Cse_sc027584.1_g010.1 (PPO) and Cse_sc031727.1_g010.1 (POD) might contribute to the degradation of anthocyanins in the petals of ‘Zi Hong Tuo Gui’ and ‘Zi Lian’ under high-temperature conditions, while simultaneously maintaining the stability of anthocyanins in ‘Zi Feng Che’ and ‘Chrystal Regal’ at the early bloom floral stage. The findings of this research provide new insights into the physiological and biochemical mechanisms by which chrysanthemum flower color responds to high-temperature stress.

Cymbidium sinense is one of the most important traditional Chinese Orchids due to its unique and highly ornamental floral organs. Although the ABCDE model for flower development is well-established in model plant species, the precise roles of these genes in C. sinense are not yet fully understood. In this study, four SEPALLATA-like genes were isolated and identified from C. sinense. CsSEP1 and CsSEP3 were grouped into the AGL9 clade, while CsSEP2 and CsSEP4 were included in the AGL2/3/4 clade. The expression pattern of CsSEP genes showed that they were significantly accumulated in reproductive tissues and expressed during flower bud development but only mildly detected or even undetected in vegetative organs. Subcellular localization revealed that CsSEP1 and CsSEP4 were localized to the nucleus, while CsSEP2 and CsSEP3 were located at the nuclear membrane. Promoter sequence analysis predicted that CsSEP genes contained a number of hormone response elements (HREs) and MADS-box binding sites. The early flowering phenotype observed in transgenic Arabidopsis plants expressing four CsSEP genes, along with the expression profiles of endogenous genes, such as SOC1, LFY, AG, FT, SEP3 and TCPs, in both transgenic Arabidopsis and C. sinense protoplasts, suggested that the CsSEP genes played a regulatory role in the flowering transition by influencing downstream genes related to flowering. However, only transgenic plants overexpressing CsSEP3 and CsSEP4 caused abnormal phenotypes of floral organs, while CsSEP1 and CsSEP2 had no effect on floral organs. Protein-protein interaction assays indicated that CsSEPs formed a protein complex with B-class CsAP3-2 and CsSOC1 proteins, affecting downstream genes to regulate floral organs and flowering time. Our findings highlighted both the functional conservation and divergence of SEPALLATA-like genes in C. sinense floral development. These results provided a valuable foundation for future studies of the molecular network underlying floral development in C. sinense.

Flower color is one of the most important ornamental traits of chrysanthemums. Previous studies have shown that high temperatures can cause the petals of some chrysanthemum varieties to fade; however, the molecular mechanisms behind this phenomenon remain poorly understood. This study examines the mechanisms of color change in purple chrysanthemums under high-temperature stress using combined metabolomic and transcriptomic analyses. Four chrysanthemum varieties—two heat-stable (‘Zi Feng Che’ and ‘Chrystal Regal’) and two heat-sensitive (‘Zi Hong Tuo Gui’ and ‘Zi Lian’)—were analyzed. High-temperature conditions (35 °C) significantly downregulated key anthocyanins in heat-sensitive varieties, particularly cyanidin-3-O-(3″,6″-O-dimalonyl)glucoside and pelargonidin-3-O-(3″,6″-O-dimalonyl)glucoside. Transcriptome analysis revealed differential gene expression involved in anthocyanin biosynthesis and degradation, with significant enrichment in the MAPK signaling, phenylpropanoid biosynthesis, flavonoid biosynthesis, and anthocyanin biosynthesis pathways. The study highlighted the differential expression of CHS, DFR, ANS, GT1, 3AT, and UGT75C1 genes in anthocyanin synthesis between heat-sensitive and heat-tolerant varieties. Compared to heat-stable varieties, the petals of heat-sensitive varieties exhibited greater differential expression of heat-responsive transcription factors, including HSFs, ERFs, MYBs, and WRKYs. Genes that show a significant negative correlation with the downregulated anthocyanins, including Cse_sc012959.1_g030.1 (βG), Cse_sc001798.1_g020.1 (MYB), Cse_sc006944.1_g010.1 (MYB), and Cse_sc000572.1_g090.1 (HSF), might regulate anthocyanin accumulation in chrysanthemums in response to high-temperature stress. These results provide guidance for the cultivation management and variety selection of chrysanthemums under high-temperature conditions. Additionally, they lay the foundation for elucidating the molecular mechanisms of flower color stability under heat stress and for breeding new heat-tolerant varieties.

Chrysanthemum is a traditional Chinese medicinal herb. Chrysanthemum extracts are rich in bioactive compounds; however, there are few reports evaluating the whitening effects of organic chrysanthemum extracts. This study assessed the antioxidant and whitening effects of organic extracts from the petals of five chrysanthemum cultivars from Guangdong, China. Significant differences were observed among the five cultivars across various parameters, including IC₅₀ values for tyrosinase inhibition activity, DPPH and ABTS values, UV absorption, and SPF values. Additionally, there were notable variations in total flavonoid, total phenolic, and chlorogenic acid contents. The BJ cultivar extract exhibited strong antioxidant capacity and superior whitening effects, containing the highest levels of total flavonoids, total phenolics, and chlorogenic acid. Correlation analysis indicated a significant relationship between total flavonoid content and IC₅₀ of DPPH, and between chlorogenic acid and both IC₅₀ of ABTS and SPF. Untargeted metabolomic analysis of three representative cultivars (BJ, WYHJ, and JSHJ) identified 22 compounds potentially related to antioxidant and whitening effects. Compounds significantly correlated with multiple antioxidant or whitening indicators (p < 0.05, r > 0.8) included tangeritin, hydroquinone, eupatilin, quercetin 3-(6″-malonyl-glucoside), biochanin A, and cyanidin 3-glucoside. These compounds may play crucial roles in the antioxidant and whitening effects of chrysanthemum extracts. The results highlight the promising antioxidant and whitening properties of chrysanthemum extracts, with certain genotypes, such as BJ, showing potential as superior raw material sources.

The complete plastid genome of Chrysanthemum morifolium ‘Anhuishiliuye’, a Chinese traditional cultivar, was determined and analyzed in this work. It had a circular-mapping molecular with the length of 151,059 bp.The LSC and SSC of 82,857 bp and 18,294 bp were separated by two IRs of 24,954 bp. The chloroplast genome of C. morifolium ‘Anhuishiliuye’ contains 125 genes, including 83 protein-coding genes, 34 ribosomal RNA genes and 8 transfer RNA genes. Phylogenetic analysis showed that C. morifolium ‘Anhuishiliuye’ clustered together with other Chrysanthemum species. The data provided would be useful for elucidation of phylogenetics and evolution in Chrysanthemum cultivars.

The projected rise in global ambient temperature by 3–5 °C by the end of this century, along with unpredicted heat waves during critical crop growth stages, can drastically reduce grain yield and will pose a great food security challenge. It is therefore important to identify wheat genetic resources able to withstand high temperatures, discover genes underpinning resilience to higher temperatures, and deploy such genetic resources in wheat breeding to develop heat-tolerant cultivars. In this study, 180 accessions of synthetic hexaploid wheats (SHWs) were evaluated under normal and late wheat growing seasons (to expose them to higher temperatures) at three locations (Islamabad, Bahawalpur, and Tando Jam), and data were collected on 11 morphological and yield-related traits. The diversity panel was genotyped with a 50 K SNP array to conduct genome-wide association studies (GWASs) for heat tolerance in SHW. A known heat-tolerance locus, TaHST1, was profiled to identify different haplotypes of this locus in SHWs and their association with grain yield and related traits in SHWs. There was a 36% decrease in grain yield (GY), a 23% decrease in thousand-grain weight (TKW), and an 18% decrease in grains per spike (GpS) across three locations in the population due to the heat stress conditions. GWASs identified 143 quantitative trait nucleotides (QTNs) distributed over all 21 chromosomes in the SHWs. Out of these, 52 QTNs were associated with morphological and yield-related traits under heat stress, while 15 of them were pleiotropically associated with multiple traits. The heat shock protein (HSP) framework of the wheat genome was then aligned with the QTNs identified in this study. Seventeen QTNs were in proximity to HSPs on chr2B, chr3D, chr5A, chr5B, chr6D, and chr7D. It is likely that QTNs on the D genome and those in proximity to HSPs may carry novel alleles for heat-tolerance genes. The analysis of TaHST1 indicated that 15 haplotypes were present in the SHWs for this locus, while hap1 showed the highest frequency of 25% (33 SHWs). These haplotypes were significantly associated with yield-related traits in the SHWs. New alleles associated with yield-related traits in SHWs could be an excellent reservoir for breeding deployment.