Making Fluorescent Markers for Corn Tissues
By Ann Perry
September 25, 2008
Kernels of corn are made up of
three main parts: the plant embryo, the endosperm surrounding the embryo, and
the hard outer pericarp. These different seed components are used in food,
animal feed and industrial products. Now a group of researchers has created
experimental corn lines with visible markers that can simplify sorting through
these distinctive kernel tissues.
Scott works in the Agricultural Research
Insects and Crop Genetics Research Unit in Ames, Iowa. He partnered with
Iowa State University scientists Colin
Shepherd, Nathalie Vignaux, Joan Peterson and Lawrence Johnson to develop
tissue markers for transgenic corn lines using green fluorescent protein (GFP).
GFP was first isolated in a single species of jellyfish. It has since been
cloned and used safely in a wide range of scientific investigations in plants
Corn processors currently identify and measure different grain tissues using
a range of markers. However, they would benefit from tools or techniques that
would allow them to measure fractionated corn seed tissues more easily and
The research team developed transgenic corn lines containing GFP as either
an embryo or an endosperm marker. They checked for GFP levels by using an
instrument that measures lightwave emissions from the fluorescent corn tissues.
In one line they developed, 100 percent of the GFP fluorescence was found in
the endosperm. In another line, about 67 percent of the GFP fluorescence was
found in the embryo.
Afterwards, the group hand-dissected about 100 grams of transgenic kernels
and identified GFP concentrations in the pericarp, embryo and endosperm
tissues. This gave them baseline levels to use for identifying different
tissues during the fractionation processes.
The researchers then dry-milled transgenic corn and produced separate grain
fractions from the pericarp, endosperm and embryo. They succeeded in
determining GFP fluorescence levels for each one. But most important, they were
also able to easily identify the mix of tissues in each--a process that
typically is expensive and time-consuming.
These results indicate that transgenic lines of corn containing GFP could be
used to optimize existing fractionation methods and improve processing
techniques. They can also support a variety of corn-related research projects,
including studies on nitrogen use and grain development.
ARS is the U.S. Department of
Agriculture's chief scientific research agency.