Rising Temperatures May Make Flowers Less Fragrant

JERUSALEM: Flowers may be losing their diverse and delicious fragrances, thanks to increasing temperatures associated with global climate change, scientists say.

Flowers produce scent to attract pollinating insects to the flowers’ reproductive organs, thereby ensuring the continued existence of plant species.

To do this, flowers assemble a mixture of dozens, and sometimes hundreds, of volatile substances from several biochemical groups.

Scientists have known for some time that increasing temperatures associated with global climate change have a negative effect on plant growth.

Expanding on this research, scientists at Hebrew University of Jerusalem in Israel have shown that increases in ambient temperature also lead to a decrease in the production of floral scents.

“Increases in temperature associated with the changing global climate are interfering with plant-pollinator mutualism, an interaction facilitated mainly by floral colour and scent,” said Alon Can’ani, a PhD student at Hebrew University of Jerusalem.

Can’ani studied control mechanisms that allow plants to regulate their production of smell, and is researching strategies to overcome the decrease in production of beneficial volatile substances, a process that requires a huge energy investment from plants.

He discovered that Petunia plants grown at elevated temperature conditions are significantly defected in production and emission of scent compounds. Increasing ambient temperature leads to a decrease in phenylpropanoid-based floral scent production in two Petunia varieties, P720 and Blue Spark, Can’ani said.

This was linked to arrested expression and activity of proteins that facilitate biosynthesis of the compounds. Can’ani also demonstrated an approach to bypass this adverse effect, by expressing the Arabidopsis thaliana PAP1 gene, which boosts the production of scent regardless of the ambient temperature.

He characterised the first gene (called PH4) that functions as a direct regulator of scent emission. When he manipulated the expression of this gene to a halt, Petunia flowers ceased to emit scent, but continued to produce it.

This gene serves as a switch between two crucial floral traits – colour and scent.

The research was published in the journal Plant, Cell and Environment.