Dissecting Metabolism of Leaf Nodules in Ardisia crenata and Psychotria punctata

Florian Schindler; Lena Fragner; Johannes B Herpell; Andreas Berger; Martin Brenner; Sonja Tischler; Anke Bellaire; Jürg Schönenberger; Weimin Li; Xiaoliang Sun; Johann Schinnerl; Lothar Brecker; Wolfram Weckwerth

doi:10.3389/fmolb.2021.683671

Dissecting Metabolism of Leaf Nodules in Ardisia crenata and Psychotria punctata

Front Mol Biosci. 2021 Jul 30:8:683671. doi: 10.3389/fmolb.2021.683671. eCollection 2021.

Authors

Florian Schindler¹, Lena Fragner^{1

2}, Johannes B Herpell¹, Andreas Berger³, Martin Brenner^{1

2

4}, Sonja Tischler^{1

2}, Anke Bellaire³, Jürg Schönenberger³, Weimin Li¹, Xiaoliang Sun², Johann Schinnerl³, Lothar Brecker⁵, Wolfram Weckwerth^{1

2}

Affiliations

¹ Molecular Systems Biology (MOSYS), Department of Functional and Evolutionary Ecology, University of Vienna, Vienna, Austria.
² Vienna Metabolomics Center (VIME), University of Vienna, Vienna, Austria.
³ Department of Botany and Biodiversity Research, University of Vienna, Vienna, Austria.
⁴ Department of Pharmaceutical Sciences/Pharmacognosy, Faculty of Life Sciences, University of Vienna, Vienna, Austria.
⁵ Department of Organic Chemistry, University of Vienna, Vienna, Austria.

Abstract

Root-microbe interaction and its specialized root nodule structures and functions are well studied. In contrast, leaf nodules harboring microbial endophytes in special glandular leaf structures have only recently gained increased interest as plant-microbe phyllosphere interactions. Here, we applied a comprehensive metabolomics platform in combination with natural product isolation and characterization to dissect leaf and leaf nodule metabolism and functions in Ardisia crenata (Primulaceae) and Psychotria punctata (Rubiaceae). The results indicate that abiotic stress resilience plays an important part within the leaf nodule symbiosis of both species. Both species showed metabolic signatures of enhanced nitrogen assimilation/dissimilation pattern and increased polyamine levels in nodules compared to leaf lamina tissue potentially involved in senescence processes and photosynthesis. Multiple links to cytokinin and REDOX-active pathways were found. Our results further demonstrate that secondary metabolite production by endophytes is a key feature of this symbiotic system. Multiple anhydromuropeptides (AhMP) and their derivatives were identified as highly characteristic biomarkers for nodulation within both species. A novel epicatechin derivative was structurally elucidated with NMR and shown to be enriched within the leaf nodules of A. crenata. This enrichment within nodulated tissues was also observed for catechin and other flavonoids indicating that flavonoid metabolism may play an important role for leaf nodule symbiosis of A. crenata. In contrast, pavettamine was only detected in P. punctata and showed no nodule specific enrichment but a developmental effect. Further natural products were detected, including three putative unknown depsipeptide structures in A. crenata leaf nodules. The analysis presents a first metabolomics reference data set for the intimate interaction of microbes and plants in leaf nodules, reveals novel metabolic processes of plant-microbe interaction as well as the potential of natural product discovery in these systems.

Keywords: GC-MS; LC-MS; NMR; SEM; metabolomics; natural products; nitrogen assimilation; plant-microbe interaction.