Here be dragons
This is a time of magic and wonder. A time of troubadours and sorcerers, of knights and dragons…
OK, plants that apparently look a bit like dragons – snapdragons as they’re known to gardeners, or antirrhinums if you want to get all fancy-pants Latin about it – indeed, they were grown by the Romans who were fond of their pleasing shapes and bright colours. But as well as making a pretty addition to a springtime border or a bridal bouquet, snapdragons hold a special place in the history of genetics.
We may think of peas as being the archetypal plant for early geneticists thanks to Mendel, but he was a big fan of snapdragons too, which he grew in his garden in Brno. Charles Darwin also had a scientific interest in snapdragons, crossing together various types with different shaped flowers to find out how the characteristics were inherited down the generations – something made nice and easy by the fact that the plants are easy to breed and come in a wide range of shapes and colours, making it easy to spot the impact of genetic changes and hybridisation.
Throughout the 20th century, snapdragons became the plant of choice for researchers seeking to understand how genes create shapes and colours, with hundreds of weird and wonderful variations popping up in labs all over the place -most notably at the John Innes Centre in Norwich, one of the world’s leading plant breeding research institutions for more than a century.
Some of these strains were most unusual, with stripy or blotchy petals instead of the usual block colour – a pattern known as variegation. This looked remarkably similar to the stripes and blotches that eminent plant geneticist Barbara McClintock had noticed on the kernels of maize corn back in the 1940s and 50s, going on to discover that the variegation was caused by jumping genes, or transposons, hopping about within the plant genome.
McClintock finally won her long-awaited Nobel Prize in 1983, attracting a lot of interest in these curious jumping genes, including the attention of Enrico Coen – a young researcher who had come to the John Innes Centre in the early 80s in search of a new project to sink his teeth into. Because they were so much easier and quicker to grow than lumbering corn plants (and prettier too), he focused his sights on stripy snapdragons.
But instead of fixating on the colour changes caused by transposons, Coen wondered whether rogue jumping genes might also occasionally land in a location containing important genes for flower development.
Together with his technician Rosemary Carpenter, Rico combed through huge fields of snapdragons, searching for the one-in-a-thousand with weird-shaped flowers that might be the result of a genetic change caused by a rogue transposon.
The hunt paid off, and by the 90s, they had pinned down many genes responsible for building the intricate shapes and structures of snapdragon flowers.
Since then, Rico and other plant biologists have focused on figuring out how these genes work to sculpt the five petals of the snapdragon flower into its characteristic roaring mouth – something that requires not only an understanding of genetics but of geometry too. And geometry means maths…
Not the kind you find on a dusty chalkboard but modern mathematical modelling, simulating silicon snapdragons inside a computer by plugging in data from real flowers and seeing what happens when you tweak their genes.
We’ve come a long way from the days of Mendel and Darwin. Today, researchers like Rico Coen can study how genetic changes affect the shape of a snapdragon without setting food in a muddy country garden. Unless, of course, they just want to smell the flowers.
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