Complete Chloroplast Genome Sequence of Freshwater Araphid Pennate Diatom Alga Synedra acus from Lake Baikal

摘要

Complete chloroplast genome of diatom alga Synedra acus possesses canonical quadripartite structure with two inverted repeats containing ribosomal RNA gene loci that separate small and large single-copy regions. Chloroplast genome maps as a circular molecule of 116 251 bp. It encodes 27 tRNAs, three rRNAs, two small RNA genes, and 128 protein-coding genes. Comparison of the genic features across diatom chloroplast genomes reveals the absence of an overlap between atpD and atpF gene coding sequences that is present in other plastid genomes of diatom origin. This feature is a clear synapomorphy of S.?acus plastid genome that is likely a result of either relaxed constraints or extensive selection forces acting upon atpF gene. We also characterized nuclear-encoded acyl-carrier protein gene with chloroplastic targeting in S.?acus . The transfer of acpp gene into the nuclear host genome is hypothesized to have occurred independently in several lineages of diatoms.