Professor Steve Jones on how Charles Darwin can put Prince Charles straight on GM crops

CHARLES DARWIN, that prince among scientists, spent long hours playing a bassoon to his plants. Charles Windsor - a prince among, well, princes - would no doubt approve: what could be more in harmony with nature than to eat organic oatmeal biscuits to the sound of a wind ensemble, and if one can hug trees, surely one might with equal profit serenade them?

 Darwin ("evolution" - quotes our future ruler - "is a man-made theory to explain the origin and continuance of life on this planet without reference to a creator") was not searching for his inner self or that of his leafy friends, but doing an experiment (a pastime not much appreciated by the heir to the throne). It led, oddly enough, straight to the world of high-tech agriculture that Prince Charles so deplores.

 Darwin's 1880 work "The Power of Movement in Plants" looked into how climbing plants twist, how others close their leaves at night, and how a few (such as the sensitive plant Mimosa pudica) respond instantly when touched. Light, its author found, sometimes had an effect, but however loud the bassoon, his subjects remained deaf to its entreaties. 

Darwin never found out how plants respond to external stimuli, but soon it became clear that chemical messages - hormones - were involved. Dozens are now known. Most do their job by binding to DNA and switching particular genes on or off.

 A decade ago botanists decided to find out how. The experiment was simple: water plants with a particular hormone and see which bits of DNA respond. At once, a previously unknown gene increased its activity by a hundred times.

 All very gratifying; but every experiment needs a control, which in this case involved sprinkling the plants with water alone. Quite unexpectedly, this too activated the newly discovered gene. Hormones had nothing to do with it.

 Simple contact had done the job. A drop of rain or a gust of wind and certain genes (now called the "touch" genes) spring into action. They slow the plant's growth. The researchers, in homage to their hero, also tried loud music and found, with Darwin, no effect.

 The touch genes led to a great family of relatives. Their various products act on the plant cell wall and cause it to firm up or loosen its fabric in response to stress. In turn that alters growth patterns and the extent to which the cells stick together. Some members of the clan respond to the passing seasons (which is why leaves fall off in autumn). 

Their proteins send signals within the cell. They are remarkably similar in structure to the molecules, the "calmodulins", that do the same job for us. Calmodulins are internal cellular messengers that, among other tasks, control our heartbeats and the hormones that determine our growth and, for that matter, our moods.

 Plant hormones are today used as weedkillers and the touch genes themselves may soon be engineered to give fruits that fall from the tree in a breath of wind as soon as they are ripe. The green movement would, of course, disapprove; and perhaps all this - to quote our Prince - just reduces the natural world to nothing more than a mechanical process.

 But is there not something magical about these impenetrable layers of scientific rationalism; about how calmodulins connect bassoons with bonsai and pattering rain with beating hearts? Why turn to mere romance in the vain search for a guiding hand?

 Plenty of romantics agree. Shelley writes of a garden in which a mimosa responds to a rejected lover's despair: "Whether the sensitive Plant, or that/ Which within its boughs like a Spirit sat,/ Ere its outward form had known decay,/ Now felt this change, I cannot say."

 Biology cannot answer that question or others like it: but Shelley filled his Oxford room with crucibles and chemicals (which hints at why his sister wrote a book so useful to those who decry Frankenstein foods). He saw no contradiction between the world of the spirit and that of science and would have been delighted to learn that cooling passions are indeed linked to falling leaves. 

And might the Prince himself be dissuaded from his mystical meanderings by the discovery that if you hug a tree you stunt its growth?
 

Steve Jones is professor of genetics at University College London