Canyon, Texas
April 5, 2006
The respiration rate of sorghum
may tell researchers what varieties will be more cold tolerant
than others, according to Texas Agricultural Experiment Station
and West Texas A&M University
researchers.
Because sorghum is a tropical plant originally from Africa,
temperatures in the Great Plains are sub-optimal for it during
germination, emergence and early seedling growth, said Dr. Bill
Payne, Experiment Station crop stress physiology researcher.
Increased seedling cold tolerance has a number of benefits for
farmers, includng earlier planting, faster and more uniform
emergence and a crop that develops and matures faster, Payne
said.
Respiration is a metabolic process essential to plant growth, he
said.
The specialized organelle in plant cells responsible for
respiration is the mitochondria.
Dr. Maria Balota, an Experiment Station research associate at
Bushland who works with Payne, is extracting mitochondria from
sorghum plants to pinpoint the basic physiologic processes that
could lead to improved performance of sorghum plants under cool
conditions.
For the past few years, Balota and Payne have grown 50 varieties
of sorghum from different regions of the world to test for
germination and emergence in a cold environment.
"The next step is to identify cold tolerance mechanisms in
sorghum," Balota said. "The breeders can use this information to
extend sorghum production into the northern regions of the
United States and into other regions of the world."
A mitochondria extraction lab has been set up by Balota and
Payne in cooperation with Dr. Bob Stewart, distinguished
professor of agriculture and director of West Texas A&M's
Dryland Agriculture Institute, and his graduate student,
Srinivas Veeragoni, in the plant soil and environmental science
department.
"We suspect the membrane of the mitochondria are responsible for
the differences among genotypes for cold tolerance," Balota
said.
Experiment Station equipment, including a centrifuge,
spectophotometer, respiration oxygraph system and incubator,
were put together with an oven and refrigerator from West Texas
A&M to create a lab equipped for extracting mitochondria and
taking respiration measurements.
"Where this really helps both of us is, we can't begin to have
all the equipment and expertise that ARS (Agricultural Research
Service) and TAES has," Stewart said. "When we partner, there is
a whole world of opportunity. And with Srinivas, Maria is
getting a young mind to stimulate the work."
Balota said not many labs are set up to concentrate on basic
plant physiology research. If the researchers can successfully
extract mitochondria, "we can do other work with organelles. It
is an essential link between genetics and whole plant or crop
physiology."
In the lab, Veeragoni grows seedlings for two days and measures
the fresh weight, as well as the rate of respiration, and then
dries plants before weighing them. He also allows plants to grow
for an additional week for mitochondria extraction and
respiration rate measurements.
"Eventually we want to compare respiration of seedlings with
that of mitochondria and with the rate of growth," Balota said.
Mitochondria extraction is still in the experimental phase, she
said.
Balota and Veeragoni are working with a variety of solutions and
buffers that will allow the mitochondria to be centrifuged and
separated, but remain alive and intact for respiration
monitoring. Once the mitochondria are extracted, Veeragoni will
measure the respiration rate.
A long-term goal of Payne and Balota is to determine if fatty
acid saturation within the mitochondrial membranes makes the
difference between cold-tolerant and intolerant sorghum
varieties.
"At that point, we can go to the enzymes and genes that are
responsible and hopefully identify molecular markers that can
indicate genes for cold tolerance," Balota said. "Then we should
be able to rapidly screen many varieties to help breeders'
efforts to develop cold-tolerant sorghum."
Writer:
Kay Ledbetter
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