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[2017-05-30] All living organisms harbour complex chemical networks inside their cells. The sum of all these chemical reactions is the driving force of life and is called metabolism. Stefano Papazian, PhD student at the Department of Plant Physiology, Umeå University, has studied how plants adapt their metabolic networks to respond to different environmental stresses. He will defend his thesis on Friday, 2nd of June 2017.

In the environment, constant exposure to both living and non-living factors make plants vulnerable to a variety of threats. As plants cannot escape, they rely on their inner chemistry to confront all sorts of challenging scenarios.

“Plants are masters of metabolism, which they can re-shape and adjust according to their different needs,” says Stefano Papazian. “We can see plants as very sophisticated chemical factories. They are able to produce thousands of different compounds, each one presenting unique biological properties.”

Most of these chemical compounds – called phytochemicals, play an important role inside the plant, for instance in the defence against insects that feed on leaves. In his research, Stefano Papazian aimed to understand how the plant chemistry helps plants to defend against insect pests, such as butterfly caterpillars and aphids.

Different insects cause different damage to the plant. While some butterfly caterpillars chew on the leaves, aphids feed by piercing through the plant surface and sucking its sap. “The plant metabolic response is very specific, and it adapts its defence strategy according to the different enemies the plant encounters,” says Stefano Papazian.

Plants produce many toxic compounds that can impair and slow down the growth of their enemies, but in order to do so, they have to balance other central metabolic activities, such as photosynthesis. Stefano Papazian’s findings show that, in addition to producing substances to defend against caterpillar and aphid attacks, plants also reconfigure their sugar composition.

In his research, Stefano Papazian also studied how air pollution by ozone affects the plant-insect interaction. “At an altitude of 50 kilometres in the atmosphere the ozone layer protects us from UV solar radiation, but at ground-level ozone is a toxic air pollutant, which affects both human health and plants”, explains Stefano Papazian. He showed in his thesis how exposure to ozone affects the growth of insects and also results in changes in the plant metabolism with negative effects on photosynthesis and the ability to defend themselves.

“If we combine ecology with the study of plant chemistry and metabolism we can improve our understanding of plant-insect interactions in nature and agriculture. This comprehensive approach can help us to predict the effects of climate change and human impact on these delicate ecosystems,” says Stefano Papazian.

Stefano Papazian was born and raised in Milano, Italy. He has a Bachelor's degree in Environmental Biotechnology from the University of Milano (Italy) and a Master´s degree in Experimental Plant Biology from Stockholm University. He performed his graduate studies at the Plant Physiology Department of Umeå University within the Umeå Plant Science Centre and in collaboration with the Swedish Metabolomics Centre.

About the public defence of the dissertation:
Friday, 2nd of June, Stefano Papazian from the Department of Plant Physiology, Umeå University will defend his thesis entitled Black Mustard and the Butterfly Effect. Metabolomics of Plant-Insect Interactions under Multiple Stress Conditions. The public defence will take place at 10.00 in ”Lilla Hörsalen” (KB.E3.01), in the KBC building at Umeå University. Faculty opponent is Professor Edward (Ted) Farmer, University of Lausanne, Switzerland.

Link to the full dissertation: urn:nbn:se:umu:diva-134653
Link to the Swedish press release on the homepage of Umeå University:

For more information, please contact:
Stefano Papazian
Umeå Plant Science Centre
Department of Plant Physiology
Umeå University

Phone: +4672 3160 854
Email: This email address is being protected from spambots. You need JavaScript enabled to view it.

Text: Stefano Papazian, Anna-Lena Lindskog
Photo: Karen Kloth