Phylogenetics of global Camellia (Theaceae) based on three nuclear regions and its implications for systematics and evolutionary history

Abstract

Camellia contains tea, oil camellia, and camellias which benefit people globally. Its infrageneric classification is, however, controversial and unstable, and former phylogenetic analyses failed to yield robust and consistent trees. Here, we aimed to reconstruct a robust phylogenetic tree, date all clades and discuss the evolutionary history of Camellia. Emphasizing the taxonomically comprehensive sampling rather than more DNA data, orthologous nuclear RPB2 introns 11-15 and 23, and waxy were sequenced for 99 taxa of Camellia to reconstruct its phylogenetic history. Ten clades are identified in Camellia: Camellia II, Camelliopsis, Corallina, Furfuracea, Heterogenea, Paracamellia, Piquetia, Stereocarpus, Thea and Yellow camellias II. Camellia grijsii and C. shensiensis are not closely related with other oil camellias that form the clade Paracamellia. Sections Camelliopsis and Theopsis together form the clade Camelliopsis, while clade Furfuracea consists of sect. Furfuracea and C. hongkongensis. Camellia connata is separated from C. lanceolata but nested in the clade Heterogenea, and C. longissima is nested in the clade Thea, suggesting a new germplasm for tea breeding. Molecular dating using four fossil calibration points suggests that the crown age of Camellia is 39.5 Ma with clade Corallina probably the earliest infrageneric clade to diversify and the most widespread clade, Paracamellia, the latest. Our findings provide new insights into the phylogenetic relationships, systematics and evolutionary history of Camellia.

1074. Camellia minutiflora Hung T. Chang

“…Ming and Bartholemew (2007). A recent paper by Dong‐Wei Zhao, Trevor Hodkinson, & John Parnell (Zhao et al, 2023) on the phylogenetics of Camellia associates C. cuspidata with C. trichoclada (Rehder) S.S.Chien and C. euryoides Lindl., both close to C . minutiflora and C. lutchuensis , though neither were included in that study.…”

Typification of six names in Camellia (Theaceae)

“…However, as a native and the single representative of Camellia in the Malay Archipelago, C. lanceolata holds a specific phylogenetic position ( Zhao et al 2022 ). The plants under the broad circumscription of this taxon show a continuous variation in the size and shape of the morphological characters.…”

Nomenclatural notes and typification of three synonyms of Camellia (Theaceae)

“…Zhang et al (2014) argued that Camellia might be a paraphyletic group in their analyses using four plastid DNA regions and the paralogous nuclear LEAFY marker. However, the monophyly of the genus was supported by investigations using complete plastid genome data (Yu et al 2017) and other nuclear sequences (Vijayan et al 2009;Li et al 2011;Zhao et al 2022). Nevertheless, nomenclatural problems should be resolved before a comprehensive phylogenetic study of the boundaries of Camellia.…”