Influence of endo-mycorrhiza on Hydrangea macrophylla subsp. serrata / tea-hortensia cultivation and dihydroisocoumarin content

M.D. Moll, A. Ziegler, M. Blings, E.-C. Schwarze, S. Hillebrand, J. Ley, T. Kraska, R. Pude
Hydrangea macrophylla subsp. serrata, also known as “tea-hortensia”, gained scientific and industrial interest because of their dihydroisocoumarin (DHC) contents of hydrangenol (HG) and phyllodulcin (PD). As HG and PD synthesis previously showed to be mainly influenced by genetics and seasonal fluctuations, new ways for increasing biomass are needed to increase total PD yield. One way is to reduce stress-related effects, e.g., water or nutrient deficiencies or UV stress. A possible way to increase stress-tolerance in plants is the inoculation with endo-mycorrhiza. This study focused on H. macrophylla subsp. serrata ‘Amagi Amacha’, a PD-rich tea-hortensia cultivar that showed low stress-resistance in previous experiments. ‘Amagi Amacha’ was inoculated with an endo-mycorrhiza inoculum and exposed to water and nutrient deficiency as well as UV-stress. Physiological reactions to the different stressors were characterized by different vegetation indices (VIs). The results showed that an inoculation with mycorrhizal fungi reduced stress in comparison to control plants. Plant height was increased in mycorrhiza treated plants, while biomass was not consistently higher in comparison to the control plants. Additionally, the effect of mycorrhiza on HG and PD was investigated. PD content was generally increased in nutrient deficient plants while reduced in UV-stressed plants (both independent of mycorrhiza infection). Tendencies of higher PD-contents in mycorrhiza-inoculated plants in comparison to control plants where observed. Besides the effect of mycorrhiza on tea-hortensias, the effectivity of different inocula was tested in a second experiment. This showed that an infection is successful with all three tested commercially available products, with carrier materials based on sand, peat, and expanded clay. The results of this study are the first results regarding the interaction of tea-hortensia and endo-mycorrhiza. Besides benefits on stress and plant growth parameters, PD-yield seems to benefit from mycorrhizal symbiosis in tea-hortensias as well.
Moll, M.D., Ziegler, A., Blings, M., Schwarze, E.-C., Hillebrand, S., Ley, J., Kraska, T. and Pude, R. (2023). Influence of endo-mycorrhiza on Hydrangea macrophylla subsp. serrata / tea-hortensia cultivation and dihydroisocoumarin content. Acta Hortic. 1372, 317-324
DOI: 10.17660/ActaHortic.2023.1372.41
Hydrangea macrophylla subsp. serrata, Hydrangea, hortensia, tea-hortensia, phyllodulcin, hydrangenol, dihydroisocourmarin, mycorrhiza, stress tolerance, vegetation indices

Acta Horticulturae