An Integrated Analytical Approach Reveals Trichome Acylsugar Metabolite Diversity in the Wild Tomato <i>Solanum pennellii</i>

Abstract

Acylsugars constitute an abundant class of pest- and pathogen-protective Solanaceae family plant-specialized metabolites produced in secretory glandular trichomes. Solanum pennellii produces copious triacylated sucrose and glucose esters, and the core biosynthetic pathway producing these compounds was previously characterized. We performed untargeted metabolomic analysis of S. pennellii surface metabolites from accessions spanning the species range, which indicated geographic trends in the acylsugar profile and revealed two compound classes previously undescribed from this species, tetraacylglucoses and flavonoid aglycones. A combination of ultrahigh-performance liquid chromatography–high resolution mass spectrometry (UHPLC–HR-MS) and NMR spectroscopy identified variations in the number, length, and branching pattern of acyl chains, and the proportion of sugar cores in acylsugars among accessions. The new dimensions of acylsugar variation revealed by this analysis further indicate variation in the biosynthetic and degradative pathways responsible for acylsugar accumulation. These findings provide a starting point for deeper investigation of acylsugar biosynthesis, an understanding of which can be exploited through crop breeding or metabolic engineering strategies to improve the endogenous defenses of crop plants.

Keywords

• acylsugar
• wild tomato
• <i>Solanum pennellii</i>
• secretory glandular trichome
• specialized metabolism
• intraspecific variation