Mitogenome Characteristics and Intracellular Gene Transfer Analysis of Four Adansonia Species

<i>Adansonia</i> L. (1753) belongs to the family Malvaceae and is commonly known as the baobab tree. This species holds significant cultural and ecological value and is often referred to as the 'tree of life.' Although its nuclear genome has been reported, the mitogenome has not yet been studied. Mitogenome research is crucial for understanding the evolution of the entire genome. In this study, we assembled and analyzed the mitogenomes of four <i>Adansonia</i> species by integrating short-read and long-read data. The results showed that the mitogenomes of all four <i>Adansonia</i> species were resolved as single circular sequences. Their total genome lengths ranged from 507,138 to 607,344 bp and contained a large number of repetitive sequences. Despite extensive and complex rearrangements between the mitogenomes of <i>Adansonia</i> and other Malvaceae species, a phylogenetic tree constructed based on protein-coding genes clearly indicated that <i>Adansonia</i> is more closely related to the <i>Bombax</i>. Selection pressure analysis suggests that the <i>rps4</i> gene in <i>Adansonia</i> may have undergone positive selection compared to other Malvaceae species, indicating that this gene may play a significant role in the evolution of <i>Adansonia</i>. Additionally, by analyzing intracellular gene transfer between the chloroplast, mitochondria, and nuclear genomes, we found that genes from the chloroplast and mitochondria can successfully transfer to each chromosome of the nuclear genome, and the <i>psbJ</i> gene from the chloroplast remains intact in both the mitochondrial and nuclear genomes. This study enriches the genetic information of <i>Adansonia</i> and provides important evidence for evolutionary research in the family Malvaceae.