In Nature this week, scientists from the UK's Medical Research Council Laboratory of Molecular Biology present a synthetic Escherichia coli capable of producing all of the bacterium's canonical amino acids from a reduced number of codons. The team recoded the full E. coli genome to generate an organism that uses 59 codons — rather than the usual 61 — to make all the amino acids, in addition to recoding one of its three stop codons. The authors write that their work "demonstrates that life can operate with a reduced number of synonymous sense codons," and that they intend to investigate additional recoding schemes and "the extent to which our approach enables sense-codon reassignment for non-canonical biopolymer synthesis."
And in Nature Genetics, a Boyce Thompson Institute-led team presents a tomato pan-genome, revealing genetic insights into the plant's domestication and a rare allele that regulates the flavor of its fruit. The scientists built the pan-genome using genome sequences of 725 phylogenetically and geographically representative accessions, and uncover more than 4,800 genes missing from the tomato reference genome. Analysis shows substantial gene loss and intense negative selection of genes and promoters during tomato domestication and improvement, including ones enriched for traits such as disease resistance. The researchers also pinpoint a rare allele selected against during domestication that plays an active role in the production of a compound that contributes to desirable flavor. The Scan has more on this, here.