Cultivation and utilization of <em>Hydrangea macrophylla</em> subsp. <em>serrata as</em> feedstock for dihydroisocoumarins and its quality-assessment through non-invasive phenotyping

Abstract

New and innovative bio-based products of today are regularly inspired by a long-known and traditional use of plants. One such example is the taste modifying phyllodulcin (PD), a dihydroisocoumarin (DHC) only present in tea-hortensias (Hydrangea macrophylla subsp. ser-rata). For industrial applications of DHCs like PD or its precursor hydrangenol (HG) in the field of innovative taste-modifying solutions or medicine, establishment of cultivation on a large scale and selection of best cultivars are needed. Therefore, a targeted quality-assessment towards DHC content and plant performance to optimize yield is imperative. Experiments on tea-hortensia cultivation at INRES – Renewable Resources and Campus Klein-Altendorf, Germany revealed that while ornamental Hydrangea benefits from shading, sun ex-posure does neither influence biomass accumulation nor HG and PD in tea-hortensias. Still, higher symptoms of stress under high sun exposure were detected via non-invasive phenotyp-ing. This trial was the first to indicate that HG and PD are genetically predetermined but not significantly affected by external stressors except for seasonal changes. <br /> Investigations of 12 sub-experiments within the second major experiment were used to develop a chemometric marker for the conversion of HG into PD. Analogue to Vegetation Indices, the chemometric Normalized Difference Phyllodulcin Index (cNDPI) could be a reliable and accu-rate tool for quantifying HG-into-PD conversion with utilization as a marker in plant breeding. <br /> In order for farmers to identify optimized harvest dates, a third experiment investigated the possibilities of non-invasive measurements to quantify HG and PD contents via hyperspectral modeling. While highly accurate models on a single-leaf scale were not obtained, approxima-tions on a field-scale showed great potential. <br /> The achieved results allow for a quality-assessment via non-invasive methods. Thus, environ-mental and management-related factors can be evaluated while parallelly estimating the quality of plant material in regard to PD content and synthesis (cNDPI). In the future, the combination in one hand-held spectrometer could bring all three compartments together to provide a holistic assessment of plant traits for farmers and breeders working with tea-hortensias.