Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Green Leaf Volatiles Increase Plant Fitness Via Biocontrol

16.10.2012
Field study published in the new scientific journal eLife reveals that biological pest control using predators of insect eggs and larvae increases plant fitness.

To solve the acute, global problem of securing food resources for a continuously growing population, we must work constantly to increase the sustainability and effectiveness of modern agricultural techniques. These efforts depend on new insights from plant ecology, particularly from work on native plants that grow in the primordial agricultural niche.


A big-eyed bug (Geocoris spp.) is attracted by green leaf volatiles and starts sucking a tobacco hornworm egg. By executing this kind of biocontrol, the tobacco plant rids itself of herbivore attackers.

Merit Motion Pictures, Winnipeg, Manitoba, Canada

Based on field studies on wild tobacco plants in the Great Basin Desert, Utah, USA, researchers of the Max Planck Institute for Chemical Ecology in Jena, Germany, demonstrated that the release of volatiles which attract enemies of herbivores not only controls insect pests, but also increases the reproduction of infested plants. Transferred to the goals of integrated pest management, this means that these natural plant defenses can be utilized to improve and increase agricultural yields in an environmentally friendly manner. These results were published on October 15, 2012, as part of the launch of the new open-access journal eLife.

Defense against herbivores is not automatically linked to yield increases

For three decades, ecologists have observed that plants emit specific volatiles after herbivory, causing a striking effect: they can reduce the number of insect attackers on a plant by up to 90 percent, because herbivores’ enemies can recognize such volatiles as a “call to dinner”. Typical examples are the attraction of parasitic wasps or predatory bugs after leaves have been attacked by moth larvae, or the underground “cry for help” emitted by maize roots to attract nematodes feeding on corn rootworm larvae. However, until now, one important question for farmers remained unanswered: Does the so-called indirect defense reaction of a plant positively influence the plant’s fitness, its vegetative and especially reproductive growth, the generation of flowers and seeds: its ability to produce grandchildren? For this cannot be taken for granted. Defense reactions, such as the emission of odor molecules or the synthesis of digestive inhibitory substances, are costly and may attract foes as well as friends, or squander resources needed for seed maturation. After defending itself, a plant may survive, but at what cost? Is it really better off than if it had simply tolerated the herbivorous foe? Natural defenses, or in other words biological control, are only useful for agriculture if they secure or, better, increase expected yield.

With only very few exceptions, plants emit green leaf volatiles (GLVs) when damaged. The GLVs released by damaged wild tobacco attract Geocoris bugs which attack herbivores, most importantly young herbivorous Manduca larvae: each Manduca larva, if allowed to grow to full size, can consume multiple full-grown wild tobacco plants! The emission of specific GLVs, including (E)-2-hexenal and related compounds, increases as soon as freshly hatched Manduca larvae start feeding on leaves – and so Geocoris can tell whether the GLVs come from Manduca feeding as opposed to any other damage. In contrast, proteinase inhibitors (PIs) are synthesized in the leaves to interfere with the digestion of leaf proteins and thus render the plant less nutritious to herbivores; hence, they can weaken feeding caterpillars. Both GLVs and PIs have been shown to reduce the number of particular herbivores, or the amount of damage they cause, for plants growing in nature over the course of short field trials. This time, researchers asked the question: do these compounds increase yield, i.e. reproduction, over the full growing season of a plant? In other words, are plants which produce these compounds really fitter than those that don’t?
In the summers of 2010 and 2011, Meredith Schuman, Kathleen Barthel and Ian Baldwin performed field experiments with transgenic GLV-deficient and PI-deficient wild tobacco plants in the plants’ native habitat, Utah, USA. They were able to demonstrate that GLV emission not only reduced the number of Manduca caterpillars and eggs on plants, but also increased flower and bud production of plants attacked by Manduca. On the other hand, no significant correlation between the formation of PIs and an increase in the number of buds or flowers was found. However, the scientists hypothesized that PIs might still weaken the caterpillars; as a consequence, the malnourished larvae might be less able to fight back against predators. This in turn could have an indirect, positive effect on flower production. To test this assumption, the researchers conducted an interesting experiment: They put Manduca larvae on either wild-type or PI-deficient plants, let them feed for two days, and subsequently imitated the attack of predatory bugs using pins and forceps. Caterpillars that had been feeding on wild-type leaves and ingesting PIs only sluggishly responded to the attack, whereas larvae that had been feeding on PI-free leaves vigorously defended themselves against the “human” assault. (Please watch the corresponding short movies at http://www.ice.mpg.de/ext/735.html)

Reduction of pesticide use

Bio-organic farming is an agricultural approach which uses biological pest control as an alternative to toxic synthetic insecticides, for example employing parasitic wasps against the dangerous larvae of the European corn borer. The results described here show that GLVs might be used to increase the effectiveness of such biological control. Like farmers using parasitic wasps, wild tobacco plants “use” Geocoris predators, attracting them with GLVs to predate Manduca herbivores. GLVs have been shown to attract other predators and parasitoids, and are emitted by all crop plants studied. “Such ‘indirect’ pest control may also help to avoid the common problem of pests developing resistance to toxic pesticides”, says Ian Baldwin from the Max Planck Institute for Chemical Ecology.

The research results presented here were published in the international journal eLife, which is being launched with support from the Howard Hughes Medical Institute, the Wellcome Trust, and the Max Planck Society. eLife represents a new model of scientific publishing, designed to meet the needs of scientists in life sciences and biomedicine in a better way. This includes free, immediate, online access to scientific articles, as well as rapid, fair, and constructive review – in short, a journal for scientists, run by scientists. Initial decisions are made by eLife’s senior editors, and, if a submission is selected for further assessment, full peer review is overseen by eLife’s 175-member board of reviewing editors. The reviewing editor and reviewers consult once peer review comments are submitted, and provide a consolidated list of instructions to authors – eliminating unnecessary and time-consuming rounds of revision. For an initial period, there will be no charge to publish in eLife. [JWK/AO]

Original Publication:
Meredith C. Schuman, Kathleen Barthel, Ian T. Baldwin (2012). Herbivory-induced volatiles function as defenses increasing fitness of the native plant Nicotiana attenuata in nature. eLife, doi: 10.7554/elife.00007

dx.doi.org/10.7554/elife.00007

Further Information:
Prof. Dr. Ian T. Baldwin, baldwin@ice.mpg.de, +49 (0)3641-57 1100
http://www.elifesciences.org/
Picture Requests:
Angela Overmeyer M.A., +49 3641 57-2110, overmeyer@ice.mpg.de
or download from http://www.ice.mpg.de/ext/735.html

Dr. Jan-Wolfhard Kellmann | Max-Planck-Institut
Further information:
http://www.elifesciences.org
http://www.ice.mpg.de

More articles from Life Sciences:

nachricht Complete skin regeneration system of fish unraveled
24.04.2018 | Tokyo Institute of Technology

nachricht Scientists generate an atlas of the human genome using stem cells
24.04.2018 | The Hebrew University of Jerusalem

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: BAM@Hannover Messe: innovative 3D printing method for space flight

At the Hannover Messe 2018, the Bundesanstalt für Materialforschung und-prüfung (BAM) will show how, in the future, astronauts could produce their own tools or spare parts in zero gravity using 3D printing. This will reduce, weight and transport costs for space missions. Visitors can experience the innovative additive manufacturing process live at the fair.

Powder-based additive manufacturing in zero gravity is the name of the project in which a component is produced by applying metallic powder layers and then...

Im Focus: Molecules Brilliantly Illuminated

Physicists at the Laboratory for Attosecond Physics, which is jointly run by Ludwig-Maximilians-Universität and the Max Planck Institute of Quantum Optics, have developed a high-power laser system that generates ultrashort pulses of light covering a large share of the mid-infrared spectrum. The researchers envisage a wide range of applications for the technology – in the early diagnosis of cancer, for instance.

Molecules are the building blocks of life. Like all other organisms, we are made of them. They control our biorhythm, and they can also reflect our state of...

Im Focus: Spider silk key to new bone-fixing composite

University of Connecticut researchers have created a biodegradable composite made of silk fibers that can be used to repair broken load-bearing bones without the complications sometimes presented by other materials.

Repairing major load-bearing bones such as those in the leg can be a long and uncomfortable process.

Im Focus: Writing and deleting magnets with lasers

Study published in the journal ACS Applied Materials & Interfaces is the outcome of an international effort that included teams from Dresden and Berlin in Germany, and the US.

Scientists at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) together with colleagues from the Helmholtz-Zentrum Berlin (HZB) and the University of Virginia...

Im Focus: Gamma-ray flashes from plasma filaments

Novel highly efficient and brilliant gamma-ray source: Based on model calculations, physicists of the Max PIanck Institute for Nuclear Physics in Heidelberg propose a novel method for an efficient high-brilliance gamma-ray source. A giant collimated gamma-ray pulse is generated from the interaction of a dense ultra-relativistic electron beam with a thin solid conductor. Energetic gamma-rays are copiously produced as the electron beam splits into filaments while propagating across the conductor. The resulting gamma-ray energy and flux enable novel experiments in nuclear and fundamental physics.

The typical wavelength of light interacting with an object of the microcosm scales with the size of this object. For atoms, this ranges from visible light to...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

Unique scope of UV LED technologies and applications presented in Berlin: ICULTA-2018

12.04.2018 | Event News

IWOLIA: A conference bringing together German Industrie 4.0 and French Industrie du Futur

09.04.2018 | Event News

 
Latest News

Quantum Technology for Advanced Imaging – QUILT

24.04.2018 | Information Technology

AWI researchers measure a record concentration of microplastic in arctic sea ice

24.04.2018 | Earth Sciences

Complete skin regeneration system of fish unraveled

24.04.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>