New Cotton Genes May Protect Against Fungi

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Jan. 18, 2001

New Cotton Genes May Protect Against Fungi

NEW ORLEANS, La. -- Scientists are testing new cotton lines that may resist

the fungi known to cause aflatoxin in seed.

The plants contain a small protein called a peptide. Shown for the first

time in test tube trials, leaf and seed extracts from cotton plants

expressing the synthetic peptide D4E1 inhibited up to 100 percent of

germinating Aspergillus flavus and other fungi within 30 minutes of

exposure.

The next step is to inoculate the cotton bolls with the fungus to see if

D4E1 stops A. flavus from germinating on the seed, says Cleveland,

who leads Agricultural Research Service's Food and Feed Safety Research Unit

in New Orleans.

A. flavus is one of 25 fungi and bacteria that succumb to D4E1. It is of

particular interest because it can contaminate cottonseed with aflatoxin.

Because it's harmful to humans and other animals, aflatoxin threatens the

marketability of cottonseed, which is processed into edible oil,

high-protein meal, and other products valued at $500-700 million annually.

Eventually, according to Cleveland, the peptides could offer a surrogate

defense for cotton plants lacking sufficient resistance to microbial

infections. This also could offset the need for chemical fungicides.

To engineer the cotton, ARS biologists Kanniah Rajasekaran and Cary

synthesized a gene for making D4E1 using a blueprint of amino acids, the

building blocks of all protein. Dow AgroSciences LLC has licensed the

technology and is collaborating with ARS under a 1998 cooperative agreement

to develop disease-resistant cottons.

The researchers used a microbe D4E1 into cotton seedling cells and

regenerated the plants for testing.

The ARS-Dow team is using specialized antibodies and mass spectrometry

techniques to determine how much D4E1 is made by cottonseed, and pinpoint

its location inside cotton cells.