On July 22, 2023, Brian Morton, professor of biological sciences, published a new paper in the journal Genes, titled “Context and Mutation in Gymnosperm Chloroplast DNA.” The research examined context and substitution at noncoding and fourfold degenerate coding sites in gymnosperm (the technical categorization of seed-producing, nonflowering plants) DNA. Mutations and subsequent repair processes are known to be strongly context-dependent in the flowering-plant chloroplast genome, and Morton sought to investigate whether this is also true for the gymnosperm group.
To accomplish this, Morton analyzed gymnosperm DNA sequences in sets of three, allowing the interference of the substitution direction and the generation of context-dependent rate matrices. Study results show significant contextual effects on the gymnosperm chloroplast DNA studied, with patterns similar to those observed in angiosperms, and that these effects most likely indicate an influence on the underlying mutation/repair dynamics. Morton also asserts that the data collected through this study extends the plastome lineages that feature very complex patterns of mutation, which can have significant effects on the evolutionary dynamics of the chloroplast genome.