Decoding corn defenses for improved pest resistance

Jan 06, 2012 By Jan Suszkiw
Decoding corn defenses for improved pest resistance
Plant physiologist Eric Schmelz (right), postdoctoral chemist Fatma Kaplan and a team of other ARS researchers have discovered new compounds that corn uses to defend against insect and fungal attack. Credit: Hans Alborn.

(PhysOrg.com) -- A clearer picture of corn's biochemical responses to insect and fungal attacks is emerging, thanks to U.S. Department of Agriculture (USDA) studies in Gainesville, Fla.

On one front, researchers identified defensive compounds, known as zealexins and kauralexins, which rapidly accumulate at fungal infection sites, impeding the microbes' continued spread.

On another front, the researchers discovered a new protein signal in corn, called ZmPep1, which alerts the plant to fungal intruders and helps mobilize a timely counterattack.

Taken together, these discoveries add significantly to the existing body of knowledge on corn's stress-coping mechanisms, and set the stage for novel approaches to improving the grain crop's insect and .

The findings were recently reported in the journals Plant Physiology and The Proceedings of the National Academy of Sciences by Alisa Huffaker, Eric Schmelz, Fatma Kaplan, Martha Vaughan, Nicole Dafoe, Xinzhi Ni, Hans T. Alborn, and Peter E.A. Teal. They are with the USDA Agricultural Research Service (ARS) Center for Medical, Agricultural and Veterinary Entomology in Gainesville. They worked on the research with colleagues at the University of Florida (UF). ARS is USDA's principal intramural scientific research agency.

Zealexins and kauralexins are derived from volatile organic compound precursors known as sesquiterpenes and diterpenes. Terpenes have been widely studied in plants, including crops such as cotton and tomatoes. However, many scientists have focused on the terpenes' production and function in response to insect-leaf feeding, rather than on what happens following stalk attack, according to Schmelz.

The ARS scientists teamed with UF chemist James Rocca to identify the compounds using techniques.

In experiments, physiologically relevant amounts of the newly discovered kauralexin class of phytoalexins inhibited the growth of anthracnose stalk rot (Colletotrichum graminicola) by 90 percent. Similarly, zealexins inhibited the growth of the aflatoxin-producing fungus Aspergillus flavus by 80 percent. These maize pathogens cause significant yield loss and fungal-derived toxin contamination issues for U.S. farmers.

Lab experiments also showed that European corn borer larvae avoided feeding on stalk tissues where kauralexins had accumulated.

Explore further: New insights into how different tissues establish their biological and functional identities

More information: Read more about this research in the January 2012 issue of Agricultural Research magazine.

Provided by USDA Agricultural Research Service

not rated yet
add to favorites email to friend print save as pdf

Related Stories

Corn lines resist fungal toxins

Sep 03, 2010

(PhysOrg.com) -- Corn germplasm lines developed by U.S. Department of Agriculture (USDA) scientists are scoring high marks in field trials for resistance to aflatoxin produced by Aspergilllus flavus and A. ...

Versatile compound examined in crops

Aug 02, 2011

Detergent-like compounds called saponins are best known for their cleansing properties, but U.S. Department of Agriculture (USDA) scientists are studying these compounds' potential for helping protect plants from insect attack.

Citrus root signals produce better biocontrol

Jan 21, 2011

Substances released into the soil by citrus tree roots when chewed on by insect pests could lead to new ways of improving the effectiveness of roundworm "first responders."

Hardy New Corn Lines Released

Oct 16, 2009

(PhysOrg.com) -- Six new inbred maize lines with resistance to aflatoxin contamination have now been registered in the United States by the Agricultural Research Service (ARS). ARS plant pathologist Robert ...

Afla-Guard also protects corn crops

Sep 03, 2010

Afla-Guard®, a biological control used to thwart the growth of fungi on peanuts, can be used on corn as well, according to a study by U.S. Department of Agriculture (USDA) scientists who helped develop it.

Recommended for you

Deadly human pathogen Cryptococcus fully sequenced

Apr 17, 2014

Within each strand of DNA lies the blueprint for building an organism, along with the keys to its evolution and survival. These genetic instructions can give valuable insight into why pathogens like Cryptococcus ne ...

User comments : 0

More news stories

Researchers successfully clone adult human stem cells

(Phys.org) —An international team of researchers, led by Robert Lanza, of Advanced Cell Technology, has announced that they have performed the first successful cloning of adult human skin cells into stem ...

Male monkey filmed caring for dying mate (w/ Video)

(Phys.org) —The incident was captured by Dr Bruna Bezerra and colleagues in the Atlantic Forest in the Northeast of Brazil.  Dr Bezerra is a Research Associate at the University of Bristol and a Professor ...

Researchers develop new model of cellular movement

(Phys.org) —Cell movement plays an important role in a host of biological functions from embryonic development to repairing wounded tissue. It also enables cancer cells to break free from their sites of ...

Impact glass stores biodata for millions of years

(Phys.org) —Bits of plant life encapsulated in molten glass by asteroid and comet impacts millions of years ago give geologists information about climate and life forms on the ancient Earth. Scientists ...