New insights into the taxonomy of tribe Euclidieae (Brassicaceae), evidence from nrITS sequence data.

Hongliang Chen,Jipei Yue,Hang Sun,Ihsan A Al-Shehbaz

doi:10.3897/phytokeys.100.24756

Hongliang Chen, Jipei Yue + Show 2 more

Open Access

https://doi.org/10.3897/phytokeys.100.24756

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Abstract

As currently delimitated, the species-rich mustard tribe Euclidieae DC. (Brassicaceae) comprises 28 genera and 152 species distributed primarily in Asia. To date, no tribe-wide comprehensive phylogenetic analysis has been conducted. In this study, sequence data from the nuclear ribosomal internal transcribed spacer (nrITS) region of 82 species in all 28 genera of Euclidieae were used to test its monophyly and infer inter- and intra-generic relationships within. Phylogenetic analyses revealed that Rhammatophyllum and Sisymbriopsis are embedded within Solms-laubachia s.l., and Solms-laubachia lanuginosa (Eurycarpus lanuginosus) fell outside the tribe. Therefore, Solms-laubachia s.l. as currently recognized is not monophyletic and its generic delimitation needed further study. Besides, our results suggest that the genera Lepidostemon, Neotorularia, and Tetracme are polyphyletic.

Highlights

The resolution of maximum parsimony (MP) analysis was relatively weaker than the outcome of Bayesian inference (BI) analysis
Our results suggested that Solms-laubachia s.l. is not monophyletic, within which both Rhammatophyllum and Sisymbriopsis are embedded
The closeness of Solms-laubachia, Rhammatophyllum, and Sisymbriopsis was revealed in previous studies (e.g., Belstein et al 2006, 2008, Warwick et al 2007, German et al 2009)

Summary

Introduction

The family is recognized morphologically, it is often difficult to assign an individual plant to a given genus, and there are tremendous controversies on generic delimitations and tribal assignments (Al-Shehbaz et al 2006, Al-Shehbaz 2012). That led Al-Shehbaz et al (2006) to propose the first phylogenetic tribal classification system based on prior molecular studies, especially the chloroplast ndhF sequences (Beilstein et al 2006), and had since been expanded to include 52 tribes (Al-Shehbaz 2012, German and Friesen 2014, Chen et al 2016). Mey. (Ali et al 2016), to name a few, demonstrate that trend

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