Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Understanding natural crop defenses

02.03.2009
Ever since insects developed a taste for vegetation, plants have faced the same dilemma: use limited resources to out-compete their neighbors for light to grow, or, invest directly in defense against hungry insects.

Now, an international team of scientists at the Salk Institute for Biological Studies and the Institute of Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agronomía (IFEVA) has discovered how plants weigh the tradeoffs and redirect their energies accordingly.

The same light sensor that detects other plants crowding in and gives the signal to switch on the synthesis of the plant growth hormone auxin reduces the plant's responsiveness to the hormone jasmonic acid, which orchestrates the synthesis of a whole array of defensive chemicals, the researchers report in an article published in the current early online edition of the Proceedings of the National Academy of Sciences.

"Understanding how plants resolve the dilemma of resource allocation on a mechanistic level opens the possibility to increase the natural defenses of crops, especially in the high density plantings typical of modern agriculture, which depend on regular applications of insecticides," explains senior author Carlos L. Ballaré, Ph.D., a senior scientist with CONICET (the National Research Council of Argentina) and associate professor at the University of Buenos Aires.

In an earlier study, Ballaré discovered that plants dial down their investment in defense when they perceive an increased risk of competition for light. But just how changes in light quality caused plants to drop their guards were still poorly understood. To connect the two, he turned to Howard Hughes Medical Institute investigator Joanne Chory, Ph.D., in the Plant Biology Laboratory at the Salk Institute and former lab member, Yi Tao, Ph.D., who had dissected the molecular pathway that plants use to adjust their growth and flowering time to shade.

Plants sense the presence of other plants in their neighborhood by the relative increase in incoming far-red light resulting from absorption of red light by canopy leaves and reflection of far-red light from neighboring plants. "When the major photoreceptor for shade avoidance detects neighbors, plants start producing the growth hormone auxin and transport it to their stems, where it helps plants grow taller," explains Chory.

But plants also react to chemical cues in the oral secretions of herbivores and mechanical damage caused by caterpillars and their ilk nibbling on foliage. They increase the production of defense-related hormones, particularly jasmonic acid, which ramps up the concentration of chemicals that make plants unpalatable or at least less nutritious for herbivores.

"Such responses incur what is known as opportunity costs," says Chory. "Resource allocation to competition can limit investment in defense, increasing vulnerability to herbivores, while allocation to defense can reduce competitive ability against neighboring plants."

And that's exactly what first author Javier E. Moreno, a graduate student in Ballaré´s lab, found. Fall armyworms—caterpillars that prefer to chomp on corn, sorghum and other members of the grass family but won't say no to beans, potatoes, peanuts, cotton and other crops—grew twice as fast on Arabidopsis thaliana seedling grown under crowded conditions or exposed to far-red radiation, the light signal plants use to detect the proximity of neighbors. Like many commercially grown crops, Arabidopsis — the lab rat of plant biologists — doesn't tolerate shade well.

But it was more than a matter of limited resources. Mutated Arabidopsis seedlings that no longer responded to far-red radiation but had normal levels of the far-red photoreceptor, still let their defenses down. At closer inspection, the researchers found that far-red radiation decreased the plants' sensitivity to jasmonates. By ignoring jasmonate signals, the plants save resources because they no long invest in defense and, at the same time, avoid the growth-inhibitory effects of jasmonates.

"Without sufficient light to keep photosynthesis going, plants won't have enough energy to invest in sophisticated defense strategies," says Ballaré. "Coupling shade avoidance syndrome with the regulation of resource allocation to defense could provide a major selective advantage for plants growing in the wild, but might increase the vulnerability of densely planted crops to insects."

Gina Kirchweger | EurekAlert!
Further information:
http://www.salk.edu

More articles from Agricultural and Forestry Science:

nachricht Energy crop production on conservation lands may not boost greenhouse gases
13.03.2017 | Penn State

nachricht How nature creates forest diversity
07.03.2017 | International Institute for Applied Systems Analysis (IIASA)

All articles from Agricultural and Forestry Science >>>

The most recent press releases about innovation >>>

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

Im Focus: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

Im Focus: Researchers Imitate Molecular Crowding in Cells

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

Northern oceans pumped CO2 into the atmosphere

27.03.2017 | Earth Sciences

Fingerprint' technique spots frog populations at risk from pollution

27.03.2017 | Life Sciences

Big data approach to predict protein structure

27.03.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>