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Abstract PremiseThe scents of volatile organic compounds (VOCs) are an important component of ripe fleshy fruit attractiveness, yet their variation across closely related wild species is poorly understood. Phylogenetic patterns in these compounds and their biosynthetic pathways offer insight into the evolutionary drivers of fruit diversity, including whether scent can communicate an honest signal of nutrient content to animal dispersers. We assessed ripe fruit VOC content across the tomato clade (Solanumsect.Lycopersicon), with implications for crop improvement since these compounds are key components of tomato flavor. MethodsWe analyzed ripe fruit volatiles from 13 species of wild tomato grown in a common garden. Interspecific variations in 66 compounds and their biosynthetic pathways were assessed in 32 accessions, and an accession‐level phylogeny was constructed to account for relatedness. ResultsWild tomato species can be differentiated by their VOCs, withSolanum pennelliinotably distinct. Phylogenetic conservatism exists to a limited extent. Major cladewide patterns corresponded to divergence of the five brightly colored‐fruited species from the nine green‐fruited species, particularly for nitrogen‐containing compounds (higher in colored‐fruited) and esters (higher in green‐fruited), the latter appearing to signal a sugar reward. ConclusionsWe established a framework for fruit scent evolution studies in a crop wild relative system, showing that each species in the tomato clade has a unique VOC profile. Differences between color groups align with fruit syndromes that could be driven by selection from frugivores. The evolution of colored fruits was accompanied by changes in biosynthetic pathways for esters and nitrogen‐containing compounds, volatiles important to tomato flavor.
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Biosystematic studies on the status of Solanum chilense
PremiseCommon taxonomic practices, which condition species' descriptions on diagnostic morphological traits, may systematically lump outcrossing species and unduly split selfing species. Specifically, higher effective population sizes and genetic diversity of obligate outcrossers are expected to result less reliable phenotypic diagnoses. Wild tomatoes, members ofSolanumsect.Lycopersicum, are commonly used as a source of exotic germplasm for improvement of the cultivated tomato, and are increasingly employed in basic research. Although the section experienced significant early work, which continues presently, the taxonomic status of many wild species has undergone a number of significant revisions and remains uncertain. Species in this section vary in their breeding systems, notably the expression of self‐incompatibility, which determines individual propensity for outcrossing MethodsHere, we examine the taxonomic status of obligately outcrossing Chilean wild tomato (Solanum chilense) using reduced‐representation sequencing (RAD‐seq), a range of phylogenetic and population genetic analyses, as well as analyses of crossing and morphological data. ResultsOverall, each of our analyses provides a considerable weight of evidence that the Pacific coastal populations and Andean inland populations of the currently describedSolanum chilenserepresent separately evolving populations, and conceal at least one undescribed cryptic species. ConclusionsDespite its vast economic importance,Solanumsect.Lycopersiconstill exhibits considerable taxonomic instability. A pattern of under‐recognition of outcrossing species may be common, not only in tomatoes, but across flowering plants. We discuss the possible causes and implications of this observation, with a focus on macroevolutionary inference.
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- PAR ID:
- 10452854
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- American Journal of Botany
- Volume:
- 108
- Issue:
- 3
- ISSN:
- 0002-9122
- Format(s):
- Medium: X Size: p. 520-537
- Size(s):
- p. 520-537
- Sponsoring Org:
- National Science Foundation
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