
Genetic Screening for Calcium
Oxalate Crystals in PlantsBy Jesús
García July 28, 2000Calcium, the fifth most abundant
element in the Earths crust, is critical to the proper functioning of the
human body. Without the one percent of calcium that is not contained in bones
and teeth, blood wouldnt clot, nerves wouldnt fire, and muscles
wouldnt contract. Could plants serve as another source of dietary calcium
for consumers? Agricultural Research Servicescientists know that calcium, in the form of oxalate crystals, accumulates
within a variety of plants. What they dont quite know yet is how to make
this calcium readily absorbable by humans. Deciphering the mechanisms that
regulate oxalate crystal formation may provide clues to making this nutrient
more biologically available and reduce the risk associated with oxalate, which
is thought to contribute to kidney stone formation. To help identify these mechanisms, ARS researchers with the
Childrens Nutrition Research
Center at Baylor College of Medicine in Texas have initiated the first
genetic screening system that can examine calcium crystal formation in plants.
The scientists used the system to screen leaves from Medicago
truncatula--a plant similar to alfalfa--that had been chemically altered so
researchers could study their crystal structure. The scientists then compared the crystal formations in these plants with
crystals in control plants. They identified differences within seven different
types, or classes, of mutants in terms of the plants crystallization
process, crystal form, distribution and/or amount. Plants in one class that contain no crystals showed no difference in their
growth when compared to controls. This finding seems to refute the hypothesis
that calcium oxalate crystals work to support plant tissue structure in the
plant under study. Researchers are also using the screening system to ascertain the genes that
determine specific crystal characteristics. Results from this research have
suggested that the process of crystal formation depends upon a complex process
involving more than seven loci, or positions, on a chromosome occupied by
genes. ARS is the U.S. Department of
Agricultures principal research agency. Scientific contact: Paul Nakata, ARS
Childrens Nutrition Research Center at Baylor College of Medicine, Houston, Texas,
phone (713) 798-6782, fax (713) 798-7096, [email protected]. U.S. Department of Agriculture |