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Article|04 Feb 2022|OPEN
Illuminating the lineage-specific diversification of resin glycoside acylsugars in the morning glory (Convolvulaceae) family using computational metabolomics
Lars H. Kruse1,2 ,† , Alexandra A. Bennett1,3 ,† , Elizabeth H. Mahood1 , Elena Lazarus1,4 , Se Jin Park1 , Frank Schroeder5 , Gaurav D. Moghe,1 ,
1Plant Biology Section, School of Integrative Plant Science, Cornell University, Ithaca, NY, 14853, USA
2Present Address: Michael Smith Laboratories, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
3Present Address: Institute of Analytical Chemistry, Universität für Bodenkultur Wien, Vienna, 1090, Austria
4Present Address: Department of Plant Biology, Carnegie Institution for Science, Stanford, CA, 94305, USA
5Boyce Thompson Institute and Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, 14853, USA
*Corresponding author. E-mail: gdm67@cornell.edu
Both authors contributed equally to the study.

Horticulture Research 9,
Article number: uhab079 (2022)
doi: https://doi.org/10.1093/hr/uhab079
Views: 448

Received: 20 Aug 2021
Revised: 12 Nov 2021
Accepted: 18 Jan 2022
Published online: 04 Feb 2022

Abstract

Acylsugars are a class of plant defense compounds produced across many distantly related families. Members of the horticulturally important morning glory (Convolvulaceae) family produce a diverse subclass of acylsugars called resin glycosides (RGs), which comprise oligosaccharide cores, hydroxyacyl chain(s), and decorating aliphatic and aromatic acyl chains. While many RG structures are characterized, the extent of structural diversity of this class in different genera and species is not known. In this study, we asked whether there has been lineage-specific diversification of RG structures in different Convolvulaceae species that may suggest diversification of the underlying biosynthetic pathways. Liquid chromatography coupled with tandem mass spectrometry (LC–MS/MS) was performed from root and leaf extracts of 26 species sampled in a phylogeny-guided manner. LC–MS/MS revealed thousands of peaks with signature RG fragmentation patterns with one species producing over 300 signals, mirroring the diversity in Solanaceae-type acylsugars. A novel RG from Dichondra argentea was characterized using nuclear magnetic resonance spectroscopy, supporting previous observations of RGs with open hydroxyacyl chains instead of closed macrolactone ring structures. Substantial lineage-specific differentiation in utilization of sugars, hydroxyacyl chains, and decorating acyl chains was discovered, especially among Ipomoea and Convolvulus—the two largest genera in Convolvulaceae. Adopting a computational, knowledge-based strategy, we further developed a high-recall workflow that successfully explained ~72% of the MS/MS fragments, predicted the structural components of 11/13 previously characterized RGs, and partially annotated ~45% of the RGs. Overall, this study improves our understanding of phytochemical diversity and lays a foundation for characterizing the evolutionary mechanisms underlying RG diversification.