Molecular phylogeny of tribe Myoporeae (Scrophulariaceae) using nuclear ribosomal DNA: Generic relationships and evidence for major clades

Abstract

Eremophila is a significant component of the Australian arid zone flora, but its generic limits and relationships to the other six genera of tribe Myoporeae remain largely untested. In this study, we assembled a dataset of the nuclear ribosomal cistron (ca. 6000 bases including ITS1+2, ETS regions, non‐transcribed spacer and associated genes) for all genera in tribe Myoporeae with a particular focus on Eremophila (205 of total 233 formally described species of Eremophila, and 28 species of related genera sampled). Phylogenetic analyses were performed using maximum likelihood and Bayesian inference methods. These resolved four major clades that were well supported. Eremophila was paraphyletic, with all other genera of tribe Myoporeae nested in it. We discuss two taxonomic options for addressing the paraphyly of Eremophila. As an immediate step, we propose that the small genera, Calamphoreus and Diocirea, should be placed in synonymy under Eremophila, and herein make the necessary new nomenclatural combinations. Additional phylogenetic data are needed, ideally in the form of multiple independent nuclear loci, to clarify the positions of Bontia, Glycocystis and Myoporum relative to Eremophila before further taxonomic changes are proposed.

Navigating through chemical space and evolutionary time across the Australian continent in plant genus Eremophila

“…Isolated serrulatane‐ and viscidane‐type diterpenoids exhibit antimalarial (Kumar et al., 2018 ), antibacterial (Algreiby et al., 2018 ; Barnes et al., 2013 ; Biva et al., 2019 ; Liu et al., 2006 ; Mon et al., 2015 ; Ndi et al., 2007a , 2007c ), antidiabetic (Tahtah et al., 2016 ; Wubshet et al., 2016 ), and antiinflammatory (Liu et al., 2006 ; Mon et al., 2015 ) properties. The presence and biosynthesis of interesting metabolites in species of Myoporeae have previously been demonstrated (Gericke et al., 2020 ; Kjaerulff et al., 2020 ; Kracht et al., 2017 ; Kumar et al., 2018 ; Ndi et al., 2007b ; Pedersen et al., 2020 ; Tahtah et al., 2016 ; Wubshet et al., 2016 ) and recent phylogenetic studies have revealed complex evolutionary relationships between genera in the tribe (Fowler et al., 2020 , 2021 ). Still only a fraction of species within the Myoporeae have had their metabolites investigated.…”

Biodiscoveries within the Australian plant genus Eremophila based on international and interdisciplinary collaboration: results and perspectives on outstanding ethical dilemmas

“…desert-loving), Eremophila species are concentrated in arid Australia, including a notable diversity hotspot in the remote regions of Western Australia (Figure 2). Eremophila is the largest genus within the plant tribe Myoporeae (Fowler et al, 2020(Fowler et al, , 2021. The aim of our study was to obtain new knowledge on the bioactivities of the natural products present across the entire genus of Eremophila using DNA sequencing and extensive chemical profiling (Gericke et al, 2021).…”

“…To expand their research on the Australian flora, a long-term collaboration was established with Bevan Buirchell for collection of native species from a range of genera including Eremophila. A collection of leaf samples from 346 plant specimens representing approximately 88% of the species in the tribe were previously established, the large majority from Western Australia (Fowler et al, 2021). Most of the specimens used for phylogenetic analyses (Fowler et al, 2020(Fowler et al, , 2021 were collected between 2013-2016 under Australian state and territory scientific flora licensing.…”

“…A collection of leaf samples from 346 plant specimens representing approximately 88% of the species in the tribe were previously established, the large majority from Western Australia (Fowler et al, 2021). Most of the specimens used for phylogenetic analyses (Fowler et al, 2020(Fowler et al, , 2021 were collected between 2013-2016 under Australian state and territory scientific flora licensing. Phylogenetic data generated based on DNA sequences from whole chloroplast genomes (Fowler et al, 2020) and nuclear ribosomal DNA (Fowler et al, 2021) showed that Eremophila is not a single evolutionary lineage and that the genera Bontia, Calamphoreus, Diocirea, Glycocystis, Myoporum and Pentacoelium are nested within it.…”

“…Most of the specimens used for phylogenetic analyses (Fowler et al, 2020(Fowler et al, , 2021 were collected between 2013-2016 under Australian state and territory scientific flora licensing. Phylogenetic data generated based on DNA sequences from whole chloroplast genomes (Fowler et al, 2020) and nuclear ribosomal DNA (Fowler et al, 2021) showed that Eremophila is not a single evolutionary lineage and that the genera Bontia, Calamphoreus, Diocirea, Glycocystis, Myoporum and Pentacoelium are nested within it. This knowledge has led to the re-classification of two genera (Calamphoreus and Diocirea), now recognized as Eremophila (Bayly et al, 2020;Fowler et al, 2021), and further generic level taxonomic change is imminent.…”