Genotypic variation in sulfur assimilation and metabolism of onion (Allium cepa L.) III. Characterization of sulfite reductase

► A SiR gene and pseudogene (φ-SiR) are expressed in A. cepa. ► Both genes are differentially expressed in onion tissues. ► SiR gene expression and enzyme activity are influenced by S-supply. ► SiR represents a regulatory point in S-assimilation.