Characterization and molecular cloning of a serine hydroxymethyltransferase 1 (OsSHM1) in rice

Serine hydroxymethyltransferase(SHMT) is important for one carbon metabolism and photorespiration in higher plants for its participation in plant growth and development,and resistance to biotic and abiotic stresses. A rice serine hydroxymethyltransferase gene, Os SHM1, an ortholog of Arabidopsis SHM1, was isolated using map-based cloning. The osshm1 mutant had chlorotic lesions and a considerably smaller,lethal phenotype under natural ambient CO2 concentrations,but could be restored to wild type with normal growth under elevated CO2levels(0.5% CO2), showing a typical photorespiratory phenotype. The data from antioxidant enzymes activity measurement suggested that osshm1 was subjected to signi fi cant oxidative stress. Also, Os SHM1 was expressed in allorgans tested(root, culm, leaf, and young panicle) but predominantly in leaves. Os SHM1 protein is localized to the mitochondria. Our study suggested that molecular function of the Os SHM1 gene is conserved in rice and Arabidopsis.