plants in the world due to the presence of a diverse set of benzylisoquinoline
alkaloids with potent pharmaceutical activities, the best known of which are the
morphinan subclass including codeine and morphine. Over the last five years we
have been funded by GlaxoSmithKline Australia to develop new poppy varieties
with improved levels of target alkaloids including noscapine, which has been used
as a human cough suppressant for decades and more recently has been shown to
have anticancer properties. While the biosynthesis of the morphinan alkaloids has
been characterised in detail over the last 20 years, very little was known about the
biosynthesis of noscapine. A major breakthrough came recently with our discovery
of a cluster of ten genes encoding five different enzyme classes responsible for
the production of noscapine (Winzer et al., 2012, Science, 336:1704-8). Functional
characterisation of a number of these genes by virus induced gene silencing
allowed a novel biosynthetic pathway to be proposed and molecular markers are
now allowing the gene cluster to be selected for as a single locus in a breeding
programme that is delivering new poppy varieties. An update on our work towards
the further characterisation of the pathway and evolution of the gene cluster will be
presented.