Molecular phylogeny reveals the non-monophyly of tribe Yinshanieae (Brassicaceae) and description of a new tribe, Hillielleae

Abstract

The taxonomic treatment within the unigeneric tribe Yinshanieae (Brassicaceae) is controversial, owing to differences in generic delimitation applied to its species. In this study, sequences from nuclear ITS and chloroplast trnL-F regions were used to test the monophyly of Yinshanieae, while two nuclear markers (ITS, ETS) and four chloroplast markers (trnL-F, trnH-psbA, rps16, rpL32-trnL) were used to elucidate the phylogenetic relationships within the tribe. Using maximum parsimony, maximum likelihood, and Bayesian inference methods, we reconstructed the phylogeny of Brassicaceae and Yinshanieae. The results show that Yinshanieae is not a monophyletic group, with the taxa splitting into two distantly related clades: one clade contains four taxa and falls in Lineage I, whereas the other includes all species previously placed in Hilliella and is embedded in the Expanded Lineage II. The tribe Yinshanieae is redefined, and a new tribe, Hillielleae, is proposed based on combined evidence from molecular phylogeny, morphology, and cytology.

Keywords: Brassicaceae; Hilliella; Hillielleae; Phylogeny; Yinshania; Yinshanieae.

Fig. 1

Selected species of Yinshanieae. (A) Y. yixianensis; (B) Y. lichuanensis; (C) Y. rivulorum; (D) Y. hunanensis; (E) Y. fumarioides; (F) and (I) Y. rupicola ssp. shuangpaiensis; (G) and (J) Y. hui; (H) and (K) Y. sinuata; (L) and (N) Y. acutangula ssp. wilsonii; (M) Y. henryi; (O) and (P) Y. zayuensis.

Fig. 2

Distributions of Yinshanieae based on field and herbarium collections. Blue and red dots represent specimens records of Yinshania and Hilliella, respectively.

Fig. 3

Phylogenetic tree resulting from Bayesian analysis of the ITS sequences of the 108 Brassicaceae species from 82 genera and Cleome lutea as outgroup. The taxa represents 49 currently recognized tribes, and their tribal assignments are given to the right. Posterior probability values are given. Hilliellaeae and Yinshanieae are highlighted in red and blue bars, respectively.

Fig. 4

Phylogenetic tree resulting from Bayesian analysis of the trnL-F sequences of 81 Brassicaceae species from 58 genera and Cleome viridiflora as outgroup. The taxa represent 37 currently recognized tribes, and their tribal assignments are given to the right. Posterior probability values are given. Hilliellaeae and Yinshanieae are highlighted in red and blue bars, respectively.

Fig. 5

Phylogenetic relationships within Yinshania inferred from Bayesian analysis of: (A) the nDNA (combined ITS and ETS) dataset; (B) the cpDNA(combined trnL-F, trnH-psbA, rps16 and rpL32-trnL) dataset; (C) the nDNA + cpDNA dataset, Cardamine flexuosa, Descurainia sophia, and Smelowskia tibetica as outgroups. Values above braches are maximum parsimony/maximum likelihood bootstrap (only show if > 50%), and values below braches are Bayesian posterior probabilities.

Fig. 6

Phylogenetic relationships within Hilliella inferred from Bayesian analysis of: (A) the nDNA (combined ITS and ETS) dataset; (B) the cpDNA (combined trnL-F, trnH-psbA, rps16 and rpL32-trnL) dataset; (C) the nDNA + cpDNA dataset. Sinalliaria limprichtiana, Eutrema heterophylhum, and Pegaeophyton scapiflorum were selected as outgroups, for the sister group of Hilliella is not clear. Values above braches are maximum parsimony/maximum likelihood bootstrap (only show if > 50%), and values below braches are Bayesian posterior probabilities. Three clades (A–C) are given on the right.