Steroidal alkaloid biosynthesis is coordinately regulated and differs among tomatoes in the red‐fruited clade

Abstract

The tomato (Solanum spp.) clade of Solanaceae features a unique assortment of cholesterol-derived steroidal alkaloids. However, little quantitative data exists reporting the profile and concentration of these alkaloids across diverse fruit germplasm. To address the lack of knowledge regarding the chemical diversity, concentration, and genetic architecture controlling tomato steroidal alkaloids, we quantitatively profiled and genotyped two tomato populations representing diversity in the red-fruited clade. We grew 107 genetically diverse fresh market, processing, landrace, and wild tomato in multiple environments. Nine steroidal alkaloid groups were quantified using ultrahigh performance liquid chromatography tandem mass spectrometry. The diversity panel and a biparental population segregating for high alpha-tomatine were genotyped to identify and validate quantitative trait loci (QTL) associated with steroidal alkaloids. Landraces and wild material exhibited higher alkaloid concentrations and more chemical diversity. Average total content of steroidal alkaloids, often dominated by lycoperoside F/G/esculeoside A, ranged from 1.9 to 23.3 mg 100 g −1 fresh wt. across accessions. Landrace and wild cherry accessions distinctly clustered based on elevated concentrations of early or late-pathway steroidal alkaloids. Significant correlations were observed among alkaloids from the early and late parts of the biosynthetic pathway in a species-dependent manner. A QTL controlling multiple, early steroidal alkaloid pathway intermediates on chromosome 3 was identified by genome-wide association studies (GWAS) and validated in a backcross population. Overall, tomato steroidal alkaloids are diverse in the red-fruited clade and their biosynthesis is regulated in a coordinated manner.

Transcriptomics and Metabolomics Reveal Tomato Consumption Alters Hepatic Xenobiotic Metabolism and Induces Steroidal Alkaloid Metabolite Accumulation in Mice

“…These data are consistent with our transcriptomics findings where phase I/II genes were differentially expressed from tomato consumption (Tables 2 and 3). A lack of glycosylated steroidal alkaloids, the predominant form in ripe tomato fruit (> 99%) [57] , is consistent with cleavage of sugars prior to uptake of the aglycone into the enterocyte of the small intestine; a documented phenomenon in many other phytochemicals such as polyphenols [58] .…”

Tomato Defenses Under Stress: The Impact of Salinity on Direct Defenses Against Insect Herbivores

“…Tomato plants under salt stress would need to significantly increase their alkaloid production within three days for this hypothesis to hold. Interestingly, we observed that salt treatment alone did not lead to upregulation of GAME4 , an upstream gene in the steroidal alkaloid biosynthesis pathway (Dzakovich, Francis and Cooperstone, 2022). We did, however, see a higher induced response ofGAME4 in herbivore-damaged salt-stressed plants, which indicates some salinity-based priming against insect herbivory.…”

Transcriptomics and Metabolomics Reveal Tomato Consumption Alters Hepatic Xenobiotic Metabolism and Induces Steroidal Alkaloid Metabolite Accumulation in Mice

“…These data are consistent with our transcriptomics findings where phase I/II genes were differentially expressed from tomato consumption (Tables 2 and 3). A lack of glycosylated steroidal alkaloids, the predominant form in ripe tomato fruit (>99%), [ 62 ] is consistent with cleavage of sugars prior to uptake of the aglycone into the enterocyte of the small intestine; a documented phenomenon in many other phytochemicals such as polyphenols. [ 63 ]…”