Yet Another Casualty of Global Warming: Petunia Perfume

Israeli student discovers that as temperatures rise, the color and scent mechanism of petunias, at least, suffers mightily.

Ruth Schuster
Ruth Schuster
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Yet another casualty of global warming: Petunia perfume, says doctoral student Alon Can'ani of Hebrew University.
Yet another casualty of global warming: Petunia perfume, says doctoral student Alon Can'ani of Hebrew University.Credit: Reuters
Ruth Schuster
Ruth Schuster

The seas are rising, ocean currents are shifting, animal and tourist migration patterns are changing and now a doctoral student in Jerusalem is telling us that global warming is also diminishing the output of scent by petunias.

Alon Can’ani had been studying the mechanisms by which petunias regulate their production of scent molecules. To clarify the point, biological scent molecules tend to be great big monster complicated things. You may think a single flower has a single hallmark “smell,” but that fragrance can be made of hundreds of different scent molecules.

Making scent molecules is a resource-heavy endeavor for a plant. It makes evolutionary sense for a flower to be able to husband its resources when necessary. And now it appears they can.

Working at the Hebrew University’s Faculty of Agriculture, Can’ani discovered that petunias grown in conditions of warmer than optimal temperature make significantly less perfume, he explains in his paper “Petunia hybrida floral scent production is negatively affected by high-temperature growth conditions,” published in the journal Plant, Cell & Environment.

It isn’t that the student took innocent seeds and grew them in an oven. As normal gardeners and botanists do, Can'ani bought cuttings from a local nursery and cultivated the cuttings in optimal temperature (22-24 degrees Celsius), he told Haaretz. Then the group of cuttings was split into two.

Some of the cuttings continued to grow in optimal conditions. The rest were grown in elevated temperature in a phytotron, a special greenhouse where the conditions can be totally controlled.

At 28 degrees, Can’ani tells Haaretz, perfume production was significantly depressed. (No great difference was noted between that temperature and an even more extreme one of 34 degrees, he noted.)

Further research uncovered that the difference in scent production was due to the heat arresting the genetic expression of specific proteins involved in perfume production.

Could this be true of all flowers? Maybe. “There is no good way to speculate whether this information is true for all flowers or just some,” Can'ani says. That will require further testing. One possible place to start is with petunia’s cousin, the tobacco plant - both are nightshades, members of the Solanaceae group.

Alon Cna'ani, PhD student at the Hebrew University’s Robert H. Smith Faculty of Agriculture, Food and Environment, shakes hands with David Bruce Smith, June 1, 2016, Jerusalem, Israel. Credit: Douglas Guthrie

Can'ani also demonstrated a way to overcome this heat-related obstacle: transgenics.

Managing to insert a gene, called PAP1, from the extremely common lab plant Arabidopsis thaliana, had the effect of eliminating the heat sensitivity of perfume production. Arabidopsis commonly lives in cold climes, says Can’ani.

Wonderful. Let’s say for the sake of argument that scent production in all flowers is heat-sensitive. Can we just go about whacking PAP1 genes into them? Is that practical? Yes and no, maybe. “Certainly transgenic plants are becoming increasingly common practice in research,” Can’ani says. “You just can’t buy them at the supermarket yet.”

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