Strong plastid degradation is consistent within section Chondrophyllae,the most speciose lineage of Gentiana
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Authors: | Peng‐ Cheng Fu,Shi‐ Long Chen,Shan‐ Shan Sun,Adrien Favre |
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Affiliation: | 1. School of Life Science, Luoyang Normal University, Luoyang P. R. China ; 2. Key Laboratory of Adaptation and Evolution of Plateau Biota, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining P. R. China ; 3. Senckenberg Research Institute and Natural History Museum, Frankfurt am Main Germany ; 4. Regional Nature Park of the Trient Valley, Salvan Switzerland |
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Abstract: | Recovering phylogenetic relationships in lineages experiencing intense diversification has always been a persistent challenge in evolutionary studies, including in Gentiana section Chondrophyllae sensu lato (s.l.). Indeed, this subcosmopolitan taxon encompasses more than 180 mostly annual species distributed around the world. We sequenced and assembled 22 new plastomes representing 21 species in section Chondrophyllae s.l. In addition to previously released plastome data, our study includes all main lineages within the section. We reconstructed their phylogenetic relationships based on protein‐coding genes and recombinant DNA (rDNA) cistron sequences, and then investigated plastome structural evolution as well as divergence time. Despite an admittedly humble species cover overall, we recovered a well‐supported phylogenetic tree based on plastome data, and found significant discordance between phylogenetic relationships and taxonomic treatments. Our results show that G. capitata and G. leucomelaena diverged early within the section, which is then further divided into two clades. The divergence time estimation showed that section Chondrophyllae s.l. evolved in the second half of the Oligocene. We found that section Chondrophyllae s.l. had the smallest average plastome size (128 KB) in tribe Gentianeae (Gentianaceae), with frequent gene and sequence losses such as the ndh complex and its flanking regions. In addition, we detected both expansion and contraction of the inverted repeat (IR) regions. Our study suggests that plastome degradation parallels the diversification of this group, and illustrates the strong discordance between phylogenetic relationships and taxonomic treatments, which now need to be carefully revised. |
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Keywords: | Gentiana phylogenomics plastome section Chondrophyllae s.l. taxonomic treatment |
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