2002 Volume 46 Issue 1 Pages 33-38
China's Yunnan province is a center for genetic diversity in Asian cultivated rice. We have conducted a collaborative research project for rice breeding using a wide diversity of genetic resources from Yunnan and Japansince 1982. We screened the germplasm collection from Yunnan for lipoxygenase-3 (LOX-3) content in embryos by using monoclonal antibodies against LOX-3. The lipoxygenase enzyme catalyzes the oxidation of unsaturated fatty acids containing a 1, 4-pentadiene structure into conjugated hydroperoxy fatty acids. The lack of lipoxygenase enzyme in rice grains may reduce oxidative deterioration during storage. We detected 22 varieties lacking LOX 3, the major component among isozymes in rice seeds, after screening 108 varieties of Yunnan rice genetic resources. Most of the varieties without LOX-3 belonged to Japonica upland rice, and to Types-4 and 6, based on esterase isozyme genotypes. Varieties without LOX-3 displayed the following agronomic characteristics: early heading, round grains, lower amylose content in the endosperm, and glabrous leaves and hulls. The lack of LOX-3 was inherited as a single recessive trait in the cross between“CI-115”lacking LOX-3 and“Norm 20”with LOX-3 activity.“CI-115”is a pure line selected from the indigenous upland variety“Chongtui”. No tight linkage was observed between the lack of LOX-3 trait and the red pericarp trait derived from“CI-115”.
