Chloroplast Genome Characterization of Benthamiella Patagonica (Benthamielleae, Solanaceae).

The Solanaceae is a globally distributed and economically important flowering plant family comprising approximately 2700-3000 species. Although extensive genomic studies have focused on major genera such as Solanum L. and Capsicum L., early-diverging lineages, including Benthamielleae Hunz., remain poorly characterized. Here, we report the first complete chloroplast (cp) genome of Benthamiella patagonica Speg., representing Benthamielleae. The cp genome (155,570 bp) exhibits the typical quadripartite structure, comprising a large single-copy region (LSC, 86,085 bp), a small single-copy region (SSC, 18,445 bp), and a pair of inverted repeats (IRs, 25,520 bp each). A total of 112 unique functional genes were annotated, including 78 protein-coding genes, 30 tRNA genes, and 4 rRNA genes, of which 18 contained introns. The infA and ycf15 genes were pseudogenized, while truncated copies of ycf1 and rps19 were detected at the IR junctions alongside their functional counterparts. When pseudogenes and duplicated genes in IRs were included, the total gene count reached 133. Comparative analyses with representative species from three Solanaceae subfamilies revealed high similarity in genome size, gene content, and GC composition. Codon usage analysis showed an A/T bias, and simple sequence repeat analysis indicated a predominance of A/T-rich mononucleotide repeats. Phylogenetic reconstruction based on 34 Solanaceae species and one outgroup placed B. patagonica as a basal lineage. The subfamily Solanoideae represented the most recently diverged clade, forming a sister group with Nicotianoideae, both rooted by Petunioideae and subsequently by B. patagonica (Benthamielleae). This newly sequenced cp genome fills a key gap in Solanaceae cp genomic resources. It can provide a valuable foundation for future studies on the taxonomy and evolutionary history of this lineage.