Phylogeny of Aconitum Subgenus Aconitum in Europe

Piotr Boroń,Józef Mitka,Bogusław Binkiewicz,Ada Wróblewska

doi:10.5586/asbp.8933

Abstract

Phylogenetic relations within Aconitum subgen. Aconitum (Ranunculaceae) in Europe are still unclear. To infer the phylogeny of the nuclear (ITS) region and chloroplast intergenic spacer trnL(UAG)-ndhF of the chloroplast DNA (cpDNA), we analyzed 64 accessions within this taxon, 58 from Europe and six from the Caucasus Mts. Nuclear ITS sequences were identical in 51 European and two Caucasian accessions, whereas the remaining sequences were unique. cpDNA sequences could be categorized into five haplotypes, i.e., A–E, including a European-Caucasian Aconitum haplotype B. Ten cpDNA sequences were unique. A 5-bp indel distinguished the diploids from the tetraploids. None of the extant European diploids were basal to the tetraploid local group. A phylogenetic tree based on combined ITS and cpDNA sequences (bayesian inference, maximum likelihood, minimal parsimony) placed Aconitum burnatii (Maritime Alps, Massif Central) and A. nevadense (Sierra Nevada, Pyrenees) in a sister group to all other European species. A Bayesian relaxed clock model estimated the earliest split of the Caucasian species during the Late Miocene [ca. 7 million years ago (Mya)], and the divergence of A. burnatii and A. nevadense from the European genetic stock during the Miocene/Pliocene (ca. 4.4 Mya). Diploids in Europe are likely to be descendants of the Miocene European-Caucasian flora linked with the ancient Asian (arctiotertiary) genetic stock. The origins of the tetraploids remain unclear, and it is possible that some tetraploids originated from local, now extinct diploids. Both the diploids and tetraploids underwent rapid differentiation in the Late Pliocene – Quaternary period.

Highlights

The family Ranunculaceae is one of the earliest diverging lineages among the eudicots (Stevens, 2001), and might have radiated within Ranunculales 121–114 million years ago (Mya) (Anderson et al, 2005), or as early as 125.8–123.0 Mya, as proposed by the “accelerated angiosperm evolution” hypothesis (W. Wang et al, 2016)
We considered the age at the divergence of the subgenera as 11.9 Mya (Park et al, 2020) for our analyses
For the chloroplast DNA (cpDNA) trnL-ndhF region, the matrix of 18 unique sequences contained a total of 899 positions, with 836 constant, 43 (5%) potentially parsimony-informative, and 20 parsimony-uninformative positions

Summary

Introduction

The family Ranunculaceae is one of the earliest diverging lineages among the eudicots (Stevens, 2001), and might have radiated within Ranunculales 121–114 million years ago (Mya) (Anderson et al, 2005), or as early as 125.8–123.0 Mya, as proposed by the “accelerated angiosperm evolution” hypothesis (W. Wang et al, 2016). The family Ranunculaceae is one of the earliest diverging lineages among the eudicots (Stevens, 2001), and might have radiated within Ranunculales 121–114 million years ago (Mya) (Anderson et al, 2005), or as early as 125.8–123.0 Mya, as proposed by the “accelerated angiosperm evolution” hypothesis Wang et al, 2016). In Ranunculales, additional evidence from phylogenetic analyses of MADS-box genes supports whole-genome duplication early in the diversification of angiosperms (Landis et al, 2018; Tank et al, 2015). The split between Aconitum and other genera occurred 24.7 Mya (Park et al, 2020), the divergence between Aconitum L. subgen.

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Conclusion