Zhiling Wang’s research while affiliated with China Agricultural University and other places

Chrysanthemum is one of the four major cut flowers in the world, with high ornamental and economic value. Fragrance is an important ornamental character of chrysanthemum flowers, especially those consumed as tea and other foods, and the flower fragrance is the major determinant of the commercial value of chrysanthemum cultivars. Currently, however, the research on chrysanthemum flower fragrance is mainly focused on the composition and content of fragrant compounds, and a clear classification of fragrance types is lacking. Here, we divided chrysanthemum fragrance into six categories based on sensory evaluation and determined the identity and content of fragrant compounds of chrysanthemum accessions representative of each fragrance type by GC-MS. In addition, we analyzed the conserved aromatic substances responsible for the fruity fragrance type chrysanthemum with multi-functional development potential, providing a theoretical basis for creating new chrysanthemum germplasm with specific fragrance types. The results of this study can accelerate the breeding process of chrysanthemum accessions with new fragrance types.

Chrysanthemum morifolium is one of the four major cut flowers in the world and has important ornamental and economic value. Flower fragrance is an important ornamental character of chrysanthemum, especially for tea and edible chrysanthemum, and the excellent fragrance determines its commercial value. At present, however, chrysanthemum is mostly chrysanthemum fragrance and medicinal fragrance, and the research on chrysanthemum flower fragrance mainly focuses on the composition and content of fragrancetic substances, and there is no clear classification of fragrance types. Here, we divided chrysanthemum fragrance into six categories by sensory evaluation, and detected the fragrance components and contents of every representative chrysanthemum with different fragrance types by GC-MS. In addition, we analyzed the genetic conservative substances of fruity fragrance chrysanthemum with multi-functional development potential, which provided a theoretical basis for creating new chrysanthemum germplasm with specific fragrance types, which was conducive to accelerating the biological breeding process of chrysanthemum with new fragrance types.

Chrysanthemum (Chrysanthemum morifolium) is well known as a photoperiod-sensitive flowering plant. However, it has also evolved into a temperature-sensitive ecotype. Low temperature can promote the floral transition of the temperature-sensitive ecotype, but little is known about the underlying molecular mechanisms. Here, we identified CmMAF2 (MADS AFFECTING FLOWERING 2), a putative MADS-box gene, which induces floral transition in response to low temperatures independent of day length conditions in this ecotype. CmMAF2 was shown to bind to the promoter of the GA biosynthesis gene, CmGA20ox1, and to directly regulate the biosynthesis of bioactive GA1 and GA4 . The elevated bioactive GAs activated CmLFY (LEAFY) expression, ultimately initiating floral transition. In addition, CmMAF2 expression in response to low temperatures was directly activated by CmC3H1, a CCCH-type zinc-finger protein upstream. In summary, our results reveal that the CmC3H1-CmMAF2 module regulates the flowering time in response to low temperatures by regulating GA biosynthesis in the temperature-sensitive chrysanthemum ecotype.

Drought is a major abiotic stress that limits plant growth and development. Adaptive mechanisms have evolved to mitigate drought stress, including the capacity to adjust water loss rate and to modify the morphology and structure of the epidermis. Here, we show that the expression of CmNF‐YB8, encoding a nuclear factor Y (NF‐Y) B‐type subunit, is lower under drought conditions in chrysanthemum (Chrysanthemum morifolium). Transgenic chrysanthemum lines in which transcript levels of CmNF‐YB8 were reduced by RNA interference (CmNF‐YB8‐RNAi) exhibited enhanced drought resistance relative to control lines, whereas lines overexpressing CmNF‐YB8 (CmNF‐YB8‐OX) were less tolerant to drought. Compared to wild type (WT), CmNF‐YB8‐RNAi plants showed reduced stomatal opening and a thicker epidermal cuticle that correlated with their water loss rate. We also identified genes involved in stomatal adjustment (CBL‐interacting protein kinase 6, CmCIPK6) and cuticle biosynthesis (CmSHN3) that are more highly expressed in CmNF‐YB8‐RNAi lines than in WT, CmCIPK6 being a direct downstream target of CmNF‐YB8. Virus‐induced gene silencing of CmCIPK6 or CmSHN3 in the CmNF‐YB8‐RNAi background abolished the effects of CmNF‐YB8‐RNAi on stomatal closure and cuticle deposition, respectively. CmNF‐YB8 thus regulates CmCIPK6 and CmSHN3 expression to alter stomatal movement and cuticle thickness in the leaf epidermis, thereby affecting drought resistance.

Volatile composition is an important feature that determines flavor, which actively affects the overall evaluation of chrysanthemum tea. In this study, HS-GC-IMS (headspace-gas chromatography-ion mobility spectrometry) was performed to characterize the volatile profiles of different chrysanthemum tea subtypes. Forty-seven volatiles of diverse chemical nature were identified and quantified. Partial least squares discriminant analysis (PLS-DA) revealed that four chrysanthemum teas were distinct from each other based on their volatile compounds. Furthermore, this work provides reference methods for detecting novel volatile organic compounds in chrysanthemum tea plants and products.