RESUMEN
The mitogenome of Bauhinia variegate was assembled and characterized in this study. The mitogenome size was 437,271 bp, and its GC content was 45.5%. 36 protein-coding genes, 17 tRNAs and 3 rRNAs were annotated in the mitogenome. A total of 12 MTPTs, ranging from 71 bp to 3562 bp, were identified in the mitogenome and covered 1.46% (6373 bp) of the mitogenome. Phylogenetic analysis of 15 species of Leguminosae based on 23 core protein-coding genes showed that B. variegata was sister to Tylosema esculentum, another member from the subfamily Cercidoideae. The mitogenome of B. variegata provides a valuable genetic resource for further phylogenetic studies of this family.
RESUMEN
Cercidoideae, one of the six subfamilies of Leguminosae, contains one genus Cercis with its chromosome number 2n = 14 and all other genera with 2n = 28. An allotetraploid origin hypothesis for the common ancestor of non-Cercis genera in this subfamily has been proposed; however, no chromosome-level genomes from Cercidoideae have been available to test this hypothesis. Here, we conducted a chromosome-level genome assembly of Bauhinia variegata to test this hypothesis. The assembled genome is 326.4 Mb with the scaffold N50 of 22.1 Mb and contains 37,996 protein-coding genes. The Ks distribution between gene pairs in the syntenic regions indicates two whole-genome duplications (WGDs): one is B. variegata-specific, and the other is shared among core eudicots. Although Ks between gene pairs generated by the recent WGD in Bauhinia is greater than that between Bauhinia and Cercis, the WGD was not detected in Cercis, which can be explained by an accelerated evolutionary rate in Bauhinia after divergence from Cercis. Ks distribution and phylogenetic analysis for gene pairs generated by the recent WGD in Bauhinia and their corresponding orthologs in Cercis support the allopolyploidy origin hypothesis of Bauhinia. The genome of B. variegata also provides a genomic resource for dissecting genetic basis of its ornamental traits.