A floral boost

It was in a greenhouse in Oakland, California in 1989 that I began to question what I thought I knew about the use of transgenes in agriculture. I had been urged to look at some transgenic petunia plants by a company to which I was a scientific advisor. The plants in front of me had deep purple petals with many white segments. Some of the plants had all-white flowers. The white segments and the patterns they created were the result of adding a transgene to ordinary purple-flowered petunias (Figure 1). The added gene encodes chalcone synthase, an enzyme important in the biosynthesis of purple petal pigments. Normal purple-flowered petunias have at least two copies of a chalcone synthase gene almost identical to the transgene. How could extra copies cause spasmodic loss of purple pigment to create such striking patterns? Here was something new and perplexing. It did not make sense and it undermined the whole basis of using transgenes to duplicate and enhance existing gene functions in plants. I had been working for many years on wheat genomics, and had been actively involved in developing the use of transgenes for research and agriculture. It was therefore something of a shock to see transgenes not behaving as predicted, and it made me itch to study these petunias. But being Director of the John Innes Institute in the UK meant that I no longer spent time at the bench satisfying my own curiosity and, in any case, these plants belonged to the company. In the late 1980s the suppression of petal colour was but one example of the unpredicted behavior of This image showing the influence of the marine compound discodermolid on a transformed mouse fibroblast was produced by Florenz Sasse in the German Research Centre for Biotechnology, Braunschweig, Germany. It is a runner-up in this year’s Current Biology Photomicrography Competition. Discodermolid induces microtubule bundling (tubulin was immunostained and appears green), which is clearly seen in the pseudopodia and near the nucleus (stained with DAPI and appearing blue). As a result of this microtubule bundling, the cell is undergoing apoptosis and fragmentation of the nucleus can be seen. Magazine R469