Yaoyi Zhang

As a special woody vegetable, Chinese toon (Toona sinensis) has a unique flavor, which is mainly formed by a combination of volatile substances. The secretion and storage of volatile odorants in plants are often carried out in trichomes. Currently, studies on the formation of T. sinensis flavor in terms of biosynthetic processes and epidermal trichome morphology are scarce. Here, we conducted a detailed analysis of the morphology, structure, and distribution of trichomes on the leaves of T. sinensis. We identified three types of trichomes: non-glandular, sessile glandular, and stalked glandular. We found that the distribution of trichomes varies greatly in the natural populations of T. sinensis, and this may be closely related to the changes in volatile components. In order to clarify the relationship between secondary metabolism and trichome formation, we integrated the metabolic analysis of volatiles with transcriptome analysis and discovered two important (Terpene Synthase) TPS genes that may be directly involved in terpene synthesis. Through the heterologous expression in tobacco and the transient expression in T. sinensis, we showed that the TPS genes can participate in the synthesis of sesquiterpenes, among which TsTPS1262 can lead to the synthesis of elemene in T. sinensis. Our study provides insights into the synthesis pathways of complex volatile components in T. sinensis and also provides a basis for flavor breeding applications.

Understanding the molecular mechanisms that regulate flower growth, development, and opening is of paramount importance, yet these processes remain less explored at the genetic level. Flower development in Hydrangea paniculata ‘Vanilla Strawberry’ is finely tuned through hormonal signals, yet the genetic underpinnings are not well defined. This study addresses the gap by examining the influence of gibberellic acid (GA3), salicylic acid (SA), and ethylene (ETH) on the flowering traits and underlying molecular responses. Treatment with 100 mg/L SA significantly improved chlorophyll content and bolstered the accumulation of soluble sugars and proteins, advancing the flowering onset by 6 days and lengthening the flowering period by 11 days. Concurrently, this treatment enhanced inflorescence dimensions, increasing length, width, and petal area by 22.76%, 26.74%, and 27.45%, respectively. Contrastingly, 100 mg/L GA3 expanded inflorescence size but postponed flowering initiation and decreased inflorescence count. Higher concentrations of SA and GA3, as well as any concentration of ETH, resulted in delayed flowering and inferior inflorescence attributes. A physiological analysis over 50 days revealed that these regulators variably affected sugar and protein levels and modified antioxidant enzyme activities. An RNA-seq analysis during floral development highlighted significant transcriptomic reprogramming, with SA treatment downregulating Myb transcription factors, implicating them in the modulation of flowering timing and stress adaptation. These findings illuminate the complex interplay between hormonal treatments, gene expression, and flowering phenotypes in Hydrangea paniculata, offering valuable perspectives for ornamental horticulture optimization.