In the early, online edition of the Proceedings of the National Academy of Sciences, researchers from the UK, New Zealand, and Nepal explore the relationship between plant phylogeny and medicinal plant compound content. Based on phylogenetic relationships they discerned from new and existing rbcL marker gene sequence data for thousands of plants from South Africa, New Zealand, and Nepal, the investigators argue that it's time to combine knowledge from traditional medicine with information about phylogenic relationships between organisms when "bioprospecting," or searching for new natural products with medicinal value. "Phylogenetic cross-cultural comparisons can focus screening efforts on a subset of traditionally used plants that are richer in bioactive compounds," they write, "and could revitalize the use of traditional knowledge in bioprospecting."
A team from Taiwan takes a look at the relationship between rates of evolution in mammalian coding exons and cytosine methylation patterns associated with these exons. Using DNA methylation data for several human cell types — combined with evolutionary analyses based on comparisons of human and mouse exons and human and macaque exons — the researchers found evidence that methylation's influence over mutation susceptibility and, subsequently, evolution is not constant across exons. Rather, they say, it varies depending on an exon's place in a gene. "Our results imply that DNA methylation level is differentially correlated with the biological (and evolutionary) features of coding exons in different genic positions," the study's authors say. "The first exons appear more prone to the mutagenic effects, whereas the other exons are more influenced by the regulatory effects of DNA methylation."
Hybrid rice plants show enhanced yield, grain weight, and grain number mainly due to pseudo-dominance and over-dominance, while additional types of interactions between parental genes influence other traits in the hybrid plants, according to another PNAS study. Chinese researchers used high-density SNP data to assess the genetics behind increased hybrid vigor, known as heterosis, in an immortalized rice population that had been made from an elite rice hybrid and tested in field studies. After assessing single-locus and epistatic interactions, the team determined that heterosis overall is a consequence of many factors — including dominance, pseudo/over-dominance, and epistasis — with variable effects on different rice traits.