Cover pictures, transgene stability and cell biology

When growing plants in the field or greenhouse, one is very conscious of seasons and thinking about when to plant, cross and harvest. But as an Editor, it is the ticking of the clock to the next issue that makes the world turn! One particular pleasure is selecting the cover picture: it must be visually appealing, highlight a particularly interesting paper in the issue, and the pictures over the year should reflect the range of research papers we publish. The October cover meets all these criteria particularly well. It shows green fluorescent protein (GFP) in multicellular trichome cells on stems of potato, and relates to the paper (which will be available in early September when the proof corrections have been returned)  “Successive silencing of tandem reporter genes in potato (Solanum tuberosum) over five-years of vegetative propagation” by a group from Charles University in Prague, Eva Nocarova, Zdenek Opatrny and Lukas Fischer.  This paper follows the expression of two transgenes, GFP and NPTII, over an extended period of five years, rather than the short period usually used to find expression of transgenes. In 25% of the lines, expression of the genes is silenced, and where this occurs, silencing of the two genes is sequential with the GFP gene being silenced first. This indicates an interconnection in the regulation and silencing of the genes, which the authors suggest may involve a change from post-transcriptional to transciptional level of the GFP gene and subsequent spreading of methylation to the NPTII gene.