Navigation Links
Understanding natural crop defenses

LA JOLLA, CA 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 Fisiolgicas y Ecolgicas Vinculadas a la Agronoma (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. Ballar, 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, Ballar 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 Ballars lab, found. Fall armywormscaterpillars 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 cropsgrew 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 Ballar. "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."


Contact: Gina Kirchweger
Salk Institute

Related biology news :

1. Biologist receives the 2008 AAAS Public Understanding of Science and Technology Award
2. Understanding phosphorus in soils is vital to proper management
3. Understanding extinct microbes may influence the state of modern human health
4. New technique is quantum leap forward in understanding proteins
5. Stowers Institutes Linheng Li Lab expands understanding of bone marrow stem cell niche
6. Understanding how oxidative stress impairs endothelial progenitor cell function
7. Caltech scientists engineer supersensitive receptor, gain better understanding of dopamine system
8. Proteins in sperm unlock understanding of male infertility says new study
9. Hidden infections crucial to understanding, controlling disease outbreaks
10. Better understanding of blood vessel constrictor needed to harness its power for patients
11. Pictures of hot fudge sundaes arouse: Understanding emotions improves our food choices
Post Your Comments:
Related Image:
Understanding natural crop defenses
(Date:6/2/2016)... , June 2, 2016   The Weather Company , ... Watson Ads, an industry-first capability in which consumers will be ... able to ask questions via voice or text and receive ... Marketers have long sought an advertising ... that can be personal, relevant and valuable; and can scale ...
(Date:5/20/2016)...  VoiceIt is excited to announce its new ... By working together, VoiceIt and VoicePass will offer ... take slightly different approaches to voice biometrics, collaboration ... usability. Both ... "This marketing and technology partnership allows ...
(Date:5/3/2016)... 2016  Neurotechnology, a provider of high-precision biometric ... Biometric Identification System (ABIS) , a complete system ... ABIS can process multiple complex biometric transactions with ... fingerprint, face or iris biometrics. It leverages the ... MegaMatcher Accelerator , which have been used ...
Breaking Biology News(10 mins):
(Date:6/23/2016)... June 23, 2016   EpiBiome , a precision ... million in debt financing from Silicon Valley Bank (SVB). ... and to advance its drug development efforts, as well ... "SVB has been an incredible strategic partner ... a traditional bank would provide," said Dr. Aeron ...
(Date:6/23/2016)... ... ... STACS DNA Inc., the sample tracking software company, today announced that Dr. ... STACS DNA as a Field Application Specialist. , “I am thrilled that Dr. ... STACS DNA. “In further expanding our capacity as a scientific integrator, Hays brings a ...
(Date:6/23/2016)... 2016 Apellis Pharmaceuticals, Inc. today announced ... of its complement C3 inhibitor, APL-2. The trials ... dose studies designed to assess the safety, tolerability, ... in healthy adult volunteers. Forty subjects ... single dose (ranging from 45 to 1,440mg) or ...
(Date:6/23/2016)... 2016 Andrew D ... Published recently in ... from touchONCOLOGY, Andrew D Zelenetz , discusses ... care is placing an increasing burden on healthcare ... therapies. With the patents on many biologics expiring, ...
Breaking Biology Technology: