Accumulation of phyllodulcin in sweet‐leaf plants of Hydrangea serrata and its neutrality in the defence against a specialist leafmining herbivore

Abstract

Among wild plants of Hydrangea serrata (Hydrangeaceae) in Japan, there are sweet plants whose leave contain a kind of isocoumarin, phyllodulcin, which happens to be 350 times as sweet as sucrose to the human tongue. In a primary beech forest in Ashu, Kyoto, the spatial distribution of sweet plants and temporal and the spatial distribution of phyllodulcin within and among plants were investigated using a high performance liquid chromatograph. The distribution of sweet plants was confined within a valley and was parapatric with non‐sweet plants. A plant's characteristic phyllodulcin accumulation did not change, even when transplanted into the different habitats. The phyllodulcin content of the sweet plants varied greatly among plants, and the population mean peaked in July when the plants flowered. Within a plant, phyllodulcin content was elevated by partial defoliation. We examined the possible effect of phyllodulcin on herbivory by a specialist leafmining herbivore, Antispila hydrangifoliella (Lepidoptera: Heliozelidae). We transplanted sweet and nonsweet plants reciprocally between their original habitats, excluded attacks by parasitoids, and compared performance of the leafminer. Leafminer colonization and larval survivorship on transplanted and in situ plants was not significantly different between sites. The fact that accumulation of phyllodulcin did not augment a defensive function, at least against herbivory by the leafminer, and the sporadic distribution of phyllodulcin‐accumulating plants, suggest that the genotypes synthesizing phyllodulcin emerged independently at separate localities by mutation, and that the genotypes are almost adaptively neutral in defence against the specialist herbivore.

Gene flow and spatio-temporal genetic variation among sympatric populations of Tetranychus kanzawai (Acari: Tetranychidae) occurring on different host plants, as estimated by microsatellite gene diversity

“…However, we found the two populations from H. macrophylla were also highly genetically differentiated from each other (F ST = 0.1013 between G A and H A , Table 3). Ujihara et al (1995) found that the content of secondary plant chemicals in hydrangea varied significantly among plant individuals and fluctuated seasonally. Thus, the restricted gene flow between the two populations from H. macrophylla found in this study is possibly due to such a seasonal change in defensive chemicals contained in H. macrophylla.…”

“…Plants of the genus Hydrangea are known to have various isocoumarin derivatives such as hydrangenol and phyllodulcin, which contribute to the defense against herbivorous insects and pathogenic fungi (Nozawa et al 1981;Hashimoto et al 1987;Ujihara et al 1995). Herbivores that do not have a detoxification system against such chemicals will suffer reduction of population growth via decline in developmental rate, survivorship, and fecundity.…”

Life-history traits of the Kanzawa spider mite Tetranychus kanzawai (Acari: Tetranychidae).

“…), containing harmful secondary chemicals for spider mites is regulated by a single dominant gene, 'T' and 'H', respectively (Gomi and Gotoh, 1996, 1997). These genes are thought to be involved in the chemical detoxification of harmful secondary chemicals, such as tannin in tea and hydrangenol in hydrangea (Dowd et al, 1983;Ujihara et al, 1995; Gomi and Gotoh, 1997; Gotoh and Gomi, 2000). Recently, T. parakanzawai Ehara, a sibling species of T. kanzawai, is found on the kudzu vine, Pueraria lobata (Willd.)…”

The establishment of efficient bioconversion, extraction, and isolation processes for the production of phyllodulcin, a potential high intensity sweetener, from sweet hydrangea leaves (Hydrangea macrophyllaThunbergii)

“…Phyllodulcin, phyllodulcin 8‐ O ‐ β ‐glucoside, phyllodulcin 3ʹ‐ O ‐ β ‐glucoside, hydrangenol, hydrangenol 8‐ β ‐glucoside, hydrangenol 4‐ O ‐glucoside, and hydrangeic acid have been reported in Hydrangea macrophylla var. thunbergii (Yoshikawa et al , ; Ujihara et al , ; Akada et al , ), whereas phyllodulcin, phyllodulcin 8‐ O‐β ‐glucoside, phyllodulcin 3ʹ‐ O‐β ‐glucoside, and hydrangenol have been identified in Hydrangea macrophylla SERINGE var. thunbergii MAKINO (Akiyama et al , ; Zehnter and Gerlach, ; Suzuki et al , ; Yoshikawa et al , ; Ujihara et al , ).…”