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ARS Home » Northeast Area » Beltsville, Maryland (BARC) » Beltsville Agricultural Research Center » National Germplasm Resources Laboratory » Research » Publications at this Location » Publication #343313
Title: Character evolution and missing (morphological) data across the core asterids (Gentianidae)

Author
item STULL, GREG - University Of Michigan
item Schori, Melanie
item SOLTIS, PAMELA - University Of Florida
item SOLTIS, DOUGLAS - University Of Florida

Submitted to: American Journal of Botany
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/8/2017
Publication Date: 4/18/2018
Citation: Stull, G., Schori, M., Soltis, P.S., Soltis, D.E. 2018. Character evolution and missing (morphological) data across the core asterids (Gentianidae). American Journal of Botany. https://doi.org/10.1002/ajb2.1050.
DOI: https://doi.org/10.1002/ajb2.1050

Interpretive Summary: Data from DNA have substantially changed current understanding of how flowering plants are related. Previously, physical characteristics were used to determine relationships. Surprisingly, relatively few studies have combined DNA data with physical characteristics to assess patterns in how these characteristics have changed among different groups of plants. In this study, data from flowers, fruits, seeds, and other characteristics were combined with data from 73 genes to see which characters were most likely present in the common ancestors of major lineages of plants. The Asteridae group is distinguished by several anatomical features and by a class of chemicals called iridoids. Fused petals, which were considered a relatively fixed trait, appear to have been gained and lost several times in this group. Within Asteridae, the Gentianidae group is distinguished by having the same number of stamens as petals, and its subgroup Lamianae has the stamens fused to the petals. Overall, the combined analysis of data highlights physical characteristics that can be used to recognize different groups within the Asteridae. However, many plants have not been closely examined for these characteristics, so more studies are needed to better understand how the groups can be recognized based on their physical features. This information is useful because fixed physical features are controlled by genes, and with a better understanding of which features appeared when in certain groups, researchers have a better chance of identifying the genes that produce and regulate the characteristics.

Technical Abstract: Character evolution and missing (morphological) data across Asteridae. Premise of the study: Our current understanding of flowering plant phylogeny provides an excellent framework for exploring various aspects of character evolution through comparative analyses. However, attempts to synthesize this phylogenetic framework with extensive morphological datasets have been surprisingly rare. Here, we explore character evolution in Asteridae (asterids), a major angiosperm clade, using an extensive morphological data set and a well-resolved phylogeny of asterids. Methods: We scored 15 phenotypic characters (spanning chemistry, vegetative anatomy, and floral, fruit, and seed features) across 248 species (including 227 asterid taxa) for ancestral state reconstruction using a phylogenetic framework based on 73 plastid genes and the same 248 species. • Key results: Iridoid production, unitegmic ovules, and cellular endosperm were all reconstructed as synapomorphic for Asteridae. Sympetaly, long associated with asterids, shows complex patterns of evolution, suggesting it arose several times independently within the clade. Stamens equal in number to the petals is likely a synapomorphy for Gentianidae, a major asterid subclade. Lamianae, a major gentianid subclade, is potentially diagnosed by adnate stamens, unilacunar nodes, and simple perforation plates. • Conclusions: The analyses presented here provide a greatly improved understanding of character evolution across Asteridae, highlighting multiple characters potentially synapomorphic for major clades. However, several important parts of the asterid tree (e.g., “early-diverging” lamiids and campanulids) are poorly known for several key phenotypic features (e.g., degree of petal fusion, integument number, nucellus type, endosperm type, iridoid production). Further morphological, anatomical, and developmental investigations of these poorly known asterids are critical for a more detailed understanding of early asterid evolution.