ISOLATION AND CHARACTERIZATION OF A GENE FOR ASSIMILATORY SULFITE REDUCTASE FROM ARABIDOPSIS-THALIANA

Sulfite reductase (SIR) represents a key enzyme in sulfate assimilatio n in higher plants. The genomic DNA sequence of the sir gene from Arab idopsis thaliana including regulatory and structural regions was isola ted and characterized. The sequence of a 6 kb fragment encoding SIR re vealed a coding region of 2891 basepairs (bp) that consists of eight e xons separated by seven introns between 83 and 139 bp in length. The t ranscription start point was determined 272 bp upstream of the transla tion start site. Southern analysis indicates a single locus for the si r gene that gives rise to a 2.4 (kb) mRNA in leaves and in roots. The promoter region was verified by functional expression of the gusA repo rter gene in transgenic A. thaliana plants and was shown to provide co rrect expression in root and leaf. (C) 1998 Elsevier Science B.V. All rights reserved.