AUTHOR=D’Andrea Lucio , Sierro Nicolas , Ouadi Sonia , Hasing Tomas , Rinaldi Elijah , Ivanov Nikolai V. , Bombarely Aureliano 

TITLE=Polyploid Nicotiana section Suaveolentes originated by hybridization of two ancestral Nicotiana clades

JOURNAL=Frontiers in Plant Science

VOLUME=14

YEAR=2023

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2023.999887

DOI=10.3389/fpls.2023.999887

ISSN=1664-462X

ABSTRACT=<sec><title>Introduction</title><p><italic>Nicotiana</italic> section <italic>Suaveolentes</italic> is an almost all-Australian clade of allopolyploid tobacco species that emerged through hybridization between diploid relatives of the genus. In this study, we aimed to assess the phylogenetic relationship of the <italic>Suaveolentes</italic> section with several <italic>Nicotiana</italic> diploid species based on both plastidial and nuclear genes. </p></sec><sec><title>Methods</title><p>The <italic>Nicotiana</italic> plastome-based phylogenetic analysis representing 47 newly re-built plastid genomes suggested that an ancestor of <italic>N</italic>. section <italic>Noctiflorae</italic> is the most likely maternal donor of the <italic>Suaveolentes</italic> clade. Nevertheless, we found clear evidence of plastid recombination with an ancestor from the <italic>Sylvestres</italic> clade. We analyzed 411 maximum likelihood-based phylogenetic trees from a set of conserved nuclear diploid single copy gene families following an approach that assessed the genomic origin of each homeolog.</p></sec><sec><title>Results</title><p>We found that <italic>Nicotiana</italic> section <italic>Suaveolentes</italic> is monophyletic with contributions from the sections <italic>Alatae</italic>, <italic>Sylvestres</italic>, <italic>Petunioides</italic> and <italic>Noctiflorae</italic>. The dating of the divergence between these sections indicates that the <italic>Suaveolentes</italic> hybridization predates the split between <italic>Alatae/Sylvestres</italic>, and <italic>Noctiflorae/Petunioides</italic>.</p></sec><sec><title>Discussion</title><p>We propose that <italic>Nicotiana</italic> section <italic>Suaveolentes</italic> arose from the hybridization of two ancestral species from which the <italic>Noctiflorae/Petunioides</italic> and <italic>Alatae/Sylvestres</italic> sections are derived, with <italic>Noctiflorae</italic> the maternal parent. This study is a good example in which the use of genome wide data provided additional evidence about the origin of a complex polyploid clade.</p></sec>