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Jerald "Snook" Pataky, U of I plant
pathologist in the College of Agricultural, Consumer and
Environmental Sciences, has researched the history of U of I's
contribution to the existence of today's supersweet corn and will be
one of the featured speakers at Agronomy Day on Aug. 21.
The supersweet sweet corn saga began in
the early 1950s, when John Laughnan, a corn
geneticist and assistant professor of botany at U of I, was
investigating the relationship between two genes: one that results
in purple pigmentation and another, called sh2, that causes kernels
to be shrunken and shriveled. As he contemplated why kernels of the
sh2 genotype were so shriveled, Laughnan discovered that the
endosperm of sh2 kernels stored less starch and four to 10 times
more sugar than endosperms of normal "sugary" sweet corn or field
corn.
In 1953, Laughnan published his work
and suggested to the sweet corn industry that his findings might be
of use in commercial sweet corn hybrids. At the time, very few sweet
corn breeders shared Laughnan's enthusiasm for the possibilities of
this new type of "supersweet" corn.
Despite a lack of support for his
ideas, Laughnan began a program to convert a few of the most popular
sweet corn inbreds to sh2. In 1961, he released through Illinois
Foundation Seeds Inc. the supersweet versions of Golden Cross Bantam
and Iochief, which became known as Illini Chief.
Since seed of Illini Chief was
difficult to produce, IFSI developed a three-way hybrid named Illini
Xtra Sweet. The company became the first to sell supersweet corn and
began to develop markets for the new product in the United States
and Japan. For the next 20 years, IFSI and Crookham Company, a
family-owned, Idaho-based seed company involved in seed production
of Illini Xtra Sweet, were the only commercial organizations with
serious supersweet breeding programs.
During this time, professors at
universities in Florida, Wisconsin and Hawaii were also developing
supersweet hybrids.
During the late 1960s and early 1970s,
A.M. "Dusty" Rhodes, a U of I professor of horticulture, discovered
the "sugary enhancer" trait in an inbred line that was developed
from a cross of Illinois sweet corn and corn with Bolivian ancestry.
This trait modified normal sugary sweet corn, resulting in about
twice as much sugar content and extremely tender kernels. Compared
with the supersweet hybrids available during this period, these new
sugary-enhancer hybrids were slightly less sweet but considerably
more tender, with a creamy texture that was missing in the
supersweet hybrids. Still, like normal sugary sweet corn, these
hybrids had a relatively short shelf-life, because sugary and
sugary-enhancer hybrids converted kernel sugars to starch after
harvest. Supersweet hybrids based on Laughnan's sh2 gene, on the
other hand, lacked ADP-glucose pyrophosphorylase, the enzyme
responsible for this conversion.
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In the early 1980s, Abbott and Cobb
Inc., a midsized, family-owned seed company, began a successful
marketing campaign to educate grocery store produce buyers and
Florida sweet corn growers about the superior extended shelf-life of
supersweet corn. Within five years, the 50,000 acres of sweet corn
produced in Florida went from less than 2 percent supersweet to over
90 percent supersweet. Soon, the same trend occurred throughout the
U.S. for all sweet corn grown for long-distance shipping.
Simultaneously, the introduction of a supersweet hybrid with traits
necessary for processing marked the beginning of canned supersweet
corn, which required no additional sugar or salt added to the can.
Disease resistance has been another
factor in the process. In the early 1980s, Rhodes and a student,
Mark Mikel, developed a new sugary-enhancer inbred that was
resistant to the maize dwarf mosaic virus. This line is a parent of
the most widely grown sweet corn hybrid in Europe. Various Rp genes,
which convey resistance to the common rust fungus, Puccinia sorghi,
were first identified in the 1960s by Art Hooker, a maize
pathologist and breeder at UI. These genes, incorporated into
supersweet and sugary-enhancer hybrids, are the primary method by
which rust is being controlled in sweet corn today. Similarly, Ht
genes identified by Hooker have been incorporated in supersweet
hybrids to control the northern leaf blight fungus.
In the past three years, Crookham
Company, IFSI and a few other companies have introduced a new type
of supersweet sweet corn that combines the beneficial attributes of
Laughnan's sh2 and Rhodes' sugary-enhancer corn. This new type of
sweet corn has the high sugar content and long shelf-life that is
characteristic of Laughnan's sh2 and the creamy texture of Rhodes'
corn. Disease resistances identified at U of I also are being
incorporated into these new Xtra Tender hybrids.
Pataky's
history of sweet corn is one of more than 20 research projects that
will be featured at Agronomy Day 2003, from 7 a.m. to 2 p.m. Aug.
21, at the Crop Sciences Research Education Center, located south of
the University of Illinois' main Urbana campus. For more
information, including directions and a listing of all of the
research projects to be presented, call (217) 333-4424 or visit
www.cropsci.uiuc.edu/agronomyday.
[University
of Illinois press release]
Related LDN article:
"Agronomy Day will feature latest research"
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