Plastome phylogenomics of the East Asian endemic genus Dobinea

Dobinea is a dioecious genus endemic to East Asia that consists of two extant species: Dobinea delavayi and Dobinea vulgaris. Although the genus is morphologically distinct, its phylogenetic position remains controversial. In this study, we investigated the phylogenetic relationships between Dobinea and related taxa by sequencing the whole plastome DNA sequences for both extant species of Dobinea and comparing them to published plastomes within Sapindales. The complete plastomes of D. vulgaris and D. delavayi were 160,683 and 160, 154 base pairs (bp) in length, including a pair of inverted repeat regions (IRs, 26,889 and 26,759 bp) divided by the large single-copy region (LSC, 87,962 and 87,555 bp) and small single-copy region (SSC, 18,943 and 19,081 bp), and identically encoded 113 unique genes (79 protein-coding genes, 30 tRNAs, and 4 rRNA genes). Plastid phylogenomic analyses showed that Dobinea was a well-supported monophyletic unit and sister to the clade including tribes Anacardieae and Rhoideae, which suggests that Dobinea is a member of Anacardiaceae. In addition, molecular dating inferred D. delavayi and D. vulgaris diverged approximately 10.76 Ma, suggesting the divergence between these two species may have been driven by the intensification of the Asian summer monsoon and the establishment of distinct monsoon regimes in East Asia.