Chrysanthemum is a popular ornamental plant with a long history of cultivation. Both the leaf and flowerhead of Chrysanthemum are known to produce diverse secondary metabolites, particularly terpenoids.
Examination of three cultivars of C. morifilium and three accessions of C. Indicum, all plants contained T-shaped trichomes and biseriate peltate glandular trichomes. The biseriate peltate glandular trichome contained two basal cells, two stalk cells, six secondary cells, and a subcuticular space, while the non-glandular T-shaped trichome was only composed of stalk cells and elongated cells. Histochemical staining analysis indicated that the biseriate peltate glandular trichome contained terpenoids and lipid oil droplets but not the T-shaped trichome.
After that, experiments were performed to determine the relationship between the accumulation and emission of the volatile terpenoids and the density of trichomes on the leaves and flowerheads in all six Chrysanthemum cultivars\accessions. A significant correlation was identified between the monoterpenoid and sesquiterpenoid content and the density of glandular trichomes on the leaves, with the correlation coefficients being 0.88, 0.86, and 0.90, respectively. In contrast, there was no significant correlation between the volatile terpenoid content and the density of T-shaped trichomes on the leaves.
In flowerheads, a significant correlation was identified between the emission rate of terpenoids and the number of glandular trichomes on the disc florets, with a correlation coefficient of 0.95. Interestingly, the correlation between the density of glandular trichomes and concentrations of terpenoids was insignificant. In summary, the relationship between trichomes and terpenoid chemistry in Chrysanthemum is established. Such knowledge may help breed aromatic Chrysanthemum cultivars by modulating the trichome trait.
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Guan, Yaqin & Chen, Sumei & Chen, Feng & Jiang, Yifan. (2022). Exploring the Relationship between Trichome and Terpene Chemistry in Chrysanthemum. Plants. 11. 1410. 10.3390/plants11111410.