Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Plants adapt their defenses to the local pest community

05.10.2012
Populations of the same plant species produce specific defenses that are effective against the predominant local pest community.
Variation in the local pest community can therefore maintain genetic variation in plants across large geographical scales. Ecologists from the University of Zurich used controlled experiments coupled with observations on natural plant populations and their pests to demonstrate how genetic variation in plant defenses is maintained. The results could be used to develop customized seeds that are more resistant to the local pest community.

Populations of the same plant species produce specific defenses that are effective against the predominant local pest community. Variation in the local pest community can therefore maintain genetic variation in plants across large geographical scales. Ecologists from the University of Zurich used controlled experiments coupled with observations on natural plant populations and their pests to demonstrate how genetic variation in plant defenses is maintained. The results could be used to develop customized seeds that are more resistant to the local pest community.

Test set-up of the selection experiment. Different genotypes of Arabidopsis thaliana were exposed to different aphids in parallel. Each individual Plexiglas box simulates a plant population with a particular composition of aphids.

UZH


Detailed view of the selection experiment. Plant populations are harmed to varying degrees by the different aphid species. From left to right: Population without aphids, mustard aphid, cabbage aphid, aphid mixture, mustard aphid, peach aphid.

Herbivorous insects, such as aphids, damage plants and can substantially reduce yields in agricultural settings; however, they can play a major role in maintaining genetic diversity. Ecologists Tobias Züst and Lindsay Turnbull from the University of Zurich together with colleagues from California and Great Britain demonstrated the importance of variation in herbivore communities using the model plant, Arabidopsis thaliana, also known as wall cress. According to Züst, the work is one of the first experimental confirmations of a forty-year-old theory that herbivorous insects exert strong selective pressure on their host plants. Moreover, plants were quick to abandon defense mechanisms when pests were absent, confirming the high costs of these defenses.

Like many other plants, Arabidopsis thaliana, or wall cress, defends itself against pests with a sophisticated chemical arsenal. The pests, however, continually evolve mechanisms to tolerate or metabolize particular chemical components. This means that depending on the abundance of different pest species, different compounds will provide optimal protection, and thus the plant needs to produce a carefully tailored cocktail that will be effective against the most likely attackers. The researchers’ first step was to study the distribution of different chemical defenses in natural populations of Arabidopsis thaliana across Europe and compare it to the geographic distribution of two important pest species: the cabbage and the mustard aphid.

Local pest populations as an evolutionary force
The scientists demonstrate that the main chemical compounds produced by Arabidopsis thaliana in South-western Europe differ from those in North-eastern Europe. This pattern correlates directly with a shift in the composition of the aphid communities. In the second step, the researchers studied experimentally whether different aphid species could directly select for these different chemical compounds under controlled conditions. To this end, they exposed mixed populations of Arabidopsis thaliana to the cabbage and mustard aphid populations typical of North-eastern or South-western Europe. After five plant generations, continuous feeding by the different aphid species led to the selection of different chemical profiles, and these were consistent with the patterns seen in nature. “There is natural variation in chemical defenses which is under genetic control”, explains Züst “and this variation is maintained by geographic variation in the composition of aphid communities”. “Genetic variation is the raw material for evolution”, he continues, “so the maintenance of genetic diversity is essential if populations are to respond to future environmental changes such as climate change or environmental degradation”.
The costs of defense
In the control populations with no aphid feeding, some of the successful genotypes from aphid populations were lost. According to Turnbull, this occurred because defense mechanisms are costly for the plant and often come at the expense of growth: “Genetic diversity was only maintained across the different treatments; within each treatment much of the diversity was lost. In the control populations, this meant the loss of defended genotypes, as here investment in costly defenses brings no benefit to the plant”. Today, the genetic diversity of many plant species is being eroded. For example, agricultural plants are selected for rapid growth and maximum yield at the expense of natural defenses, making the use of pesticides inevitable. In future, the new findings could be used to develop customized seeds that are more resistant to specific local pest communities, thus limiting the use of pesticides.
Further reading:
Tobias Züst, Christian Heichinger, Ueli Grossniklaus, Richard Harrington, Daniel J. Kliebenstein, Lindsay Turnbull. Natural enemies drive geographic variation in plant defenses. Science. October 5, 2012, doi: 10.1126/science.1226397.
Contact:
Dr Tobias Züst
Department of Ecology and Evolutionary Biology
Cornell University
Phone +1 607 319 99 05
e-mail: tobias.zuest@cornell.edu
Dr. Lindsay Turnbull
Institute of Evolutionary Biology and Environmental Sciences
University of Zurich
Phone +41 44 635 61 20
e-mail: lindsay.turnbull@ieu.uzh.ch

Nathalie Huber | Universität Zürich
Further information:
http://www.uzh.ch

More articles from Life Sciences:

nachricht Topologische Quantenchemie
21.07.2017 | Max-Planck-Institut für Chemische Physik fester Stoffe

nachricht Topological Quantum Chemistry
21.07.2017 | Max-Planck-Institut für Chemische Physik fester Stoffe

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Manipulating Electron Spins Without Loss of Information

Physicists have developed a new technique that uses electrical voltages to control the electron spin on a chip. The newly-developed method provides protection from spin decay, meaning that the contained information can be maintained and transmitted over comparatively large distances, as has been demonstrated by a team from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute. The results have been published in Physical Review X.

For several years, researchers have been trying to use the spin of an electron to store and transmit information. The spin of each electron is always coupled...

Im Focus: The proton precisely weighted

What is the mass of a proton? Scientists from Germany and Japan successfully did an important step towards the most exact knowledge of this fundamental constant. By means of precision measurements on a single proton, they could improve the precision by a factor of three and also correct the existing value.

To determine the mass of a single proton still more accurate – a group of physicists led by Klaus Blaum and Sven Sturm of the Max Planck Institute for Nuclear...

Im Focus: On the way to a biological alternative

A bacterial enzyme enables reactions that open up alternatives to key industrial chemical processes

The research team of Prof. Dr. Oliver Einsle at the University of Freiburg's Institute of Biochemistry has long been exploring the functioning of nitrogenase....

Im Focus: The 1 trillion tonne iceberg

Larsen C Ice Shelf rift finally breaks through

A one trillion tonne iceberg - one of the biggest ever recorded -- has calved away from the Larsen C Ice Shelf in Antarctica, after a rift in the ice,...

Im Focus: Laser-cooled ions contribute to better understanding of friction

Physics supports biology: Researchers from PTB have developed a model system to investigate friction phenomena with atomic precision

Friction: what you want from car brakes, otherwise rather a nuisance. In any case, it is useful to know as precisely as possible how friction phenomena arise –...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Closing the Sustainability Circle: Protection of Food with Biobased Materials

21.07.2017 | Event News

»We are bringing Additive Manufacturing to SMEs«

19.07.2017 | Event News

The technology with a feel for feelings

12.07.2017 | Event News

 
Latest News

NASA looks to solar eclipse to help understand Earth's energy system

21.07.2017 | Earth Sciences

Stanford researchers develop a new type of soft, growing robot

21.07.2017 | Power and Electrical Engineering

Vortex photons from electrons in circular motion

21.07.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>