Arabidopsis ETHE1 Encodes a Sulfur Dioxygenase That Is Essential for Embryo and Endosperm Development

Mutations in human ( Homo sapiens ) ETHYLMALONIC ENCEPHALOPATHY PROTEIN1 ( ETHE1 ) result in the complex metabolic disease ethylmalonic encephalopathy, which is characterized in part by brain lesions, lactic acidemia, excretion of ethylmalonic acid, and ultimately death. ETHE1 -like genes are found in a wide range of organisms; however, the biochemical and physiological role(s) of ETHE1 have not been examined outside the context of ethylmalonic encephalopathy. In this study we characterized Arabidopsis ( Arabidopsis thaliana ) ETHE1 and determined the effect of an ETHE1 loss-of-function mutation to investigate the role(s) of ETHE1 in plants. Arabidopsis ETHE1 is localized in the mitochondrion and exhibits sulfur dioxygenase activity. Seeds homozygous for a DNA insertion in ETHE1 exhibit alterations in endosperm development that are accompanied by a delay in embryo development followed by embryo arrest by early heart stage. Strong ETHE1 labeling was observed in the peripheral and chalazal endosperm of wild-type seeds prior to cellularization. Therefore, ETHE1 appears to play an essential role in regulating sulfide levels in seeds.