title: One-seeded fruits in the core Caryophyllales: their origin and structural diversity.
abstract: The core Caryophyllales consist of approximately 30 families (12,000 species) distributed worldwide. Many members evolved one-seeded or conjoined fruits, but their origin and structural diversity have not been investigated. A comparative anatomical investigation of the one-seeded fruits within the core Caryophyllales was conducted. The origin of the one-seeded fruits and the evolutionary reconstructions of some carpological characters were traced using a tree based on rbcl and matK data in order to understand the ancestral characters and their changes. The one-seeded fruit type is inferred to be an ancestral character state in core Caryophyllales, with a subsequent increase in the seed number seen in all major clades. Most representatives of the 'Earlier Diverging' clade are distinguished in various carpological traits. The organization of the pericarp is diverse in many groups, although fruits with a dry, many-layered pericarp, consisting of sclerenchyma as outer layers and a thin-walled parenchyma below, with seeds occupying a vertical embryo position, are likely ancestral character states in the core Caryophyllales clade. Several carpological peculiarities in fruit and seed structure were discovered in obligate one-seeded Achatocarpaceae, Chenopodiaceae, Nyctaginaceae, Seguieriaceae and Sarcobataceae. The horizontal embryo evolved in only certain groups of Chenopodiaceae. The bar-thickening of endotegmen cells appears to be an additional character typical of core Caryophyllales. The syncarpy-to-lysicarpy paradigm in Caryophyllaceae needs to be reinterpreted.
authors.affiliation: Department of Higher Plants, Faculty of Biology, Lomonosov Moscow State University, Moscow, Russia.
authors.forename: Alexander P
authors.initials: AP
authors.lastname: Sukhorukov
authors.affiliation: Florida Museum of Natural History, University of Florida, Gainesville, Florida, United States of America.
authors.forename: Evgeny V
authors.initials: EV
authors.lastname: Mavrodiev
authors.affiliation: Department of Botany, University of Zululand, KwaDlangezwa 3880, KwaZulu-Natal, South Africa.
authors.forename: Madeleen
authors.initials: M
authors.lastname: Struwig
authors.affiliation: Department of Higher Plants, Faculty of Biology, Lomonosov Moscow State University, Moscow, Russia.
authors.forename: Maya V
authors.initials: MV
authors.lastname: Nilova
authors.affiliation: Department of Higher Plants, Faculty of Biology, Lomonosov Moscow State University, Moscow, Russia.
authors.forename: Khalima Kh
authors.initials: KKh
authors.lastname: Dzhalilova
authors.affiliation: Department of Geobotany, Faculty of Biology, Lomonosov Moscow State University, Moscow, Russia.
authors.forename: Sergey A
authors.initials: SA
authors.lastname: Balandin
authors.affiliation: Herbarium, Central Siberian Botanical Garden, Siberian Branch of Russian Academy of Sciences, Novosibirsk, Russia.
authors.forename: Andrey
authors.initials: A
authors.lastname: Erst
authors.affiliation: Department of Higher Plants, Faculty of Biology, Lomonosov Moscow State University, Moscow, Russia.
authors.forename: Anastasiya A
authors.initials: AA
authors.lastname: Krinitsyna
mesh_terms: D001499:Bayes Theorem; D005075:Biological Evolution; D029748:Caryophyllaceae / Q000145:classification / Q000235:genetics*; D005638:Fruit / Q000235:genetics; D016013:Likelihood Functions; D010802:Phylogeny; D012639:Seeds / Q000033:anatomy & histology