Tissue specificity of (E)-β-farnesene and germacrene D accumulation in pyrethrum flowers

• DOI: 10.1016/j.phytochem.2021.112768
• Publication Date: 2021-04-28T11:32:58Z
• Authors: Jinjin Li; Hao Hu; Yu Chen; Jing Xie; Jiawen Li; Tuo Zeng; Manqun Wang; Jing Luo; Riru Zheng; Maarten A. Jongsma; Caiyun Wang
• Keywords: (E)-β-farnesene; 0301 basic medicine; Secretory duct; Chrysanthemum cinerariifolium; NADI staining; Terpenes; Asterales; Pyrethrum; Biodiversity; Flowers; Asteraceae; Tracheophyta; Magnoliopsida; Sesquiterpenes, Germacrane; 03 medical and health sciences; Organ Specificity; Aphids; Animals; Tanacetum cinerariifolium; Plantae; Germacrene D; Sesquiterpenes; Taxonomy

Plant defensive mimicry based on the aphid alarm pheromone (E)-β-farnesene (EβF) was previously shown to operate in Tanacetum cinerariifolium (Asteraceae) flowers. Germacrene D (GD), is another dominant volatile of T. cinerariifolium flowers and may modulate both defense and pollination. Here, we find that the increase in GD/EβF ratio at later developmental stages is correlated with the tissue distribution in the flower head: the total content of EβF and GD is similar, but GD accumulates comparatively more in the upper disk florets. Naphthol and N, N-dimethyl-p-phenylenediamine dihydrochloride (NADI)-stained purple ducts containing EβF and GD, were observed in the five petal lips of the corolla and two-lobed stigma of disk florets. By contrast in the peduncle, EβF accounts for nearly 80% of total terpenes, compared to 5% for GD. EβF is accumulated inside inner cortex cells and parenchyma cells of the pith in young peduncle. This is followed by the formation of terpene-filled axial secretory cavities parallel to the vascular bundles. In conclusion, the observed developmental and diurnal emissions of different EβF/GD ratios appear to be regulated by their tissue distribution.