STRUCTURAL-ANALYSIS OF THE CHLOROPLASTIC AND CYTOPLASMIC ALDOLASE-ENCODING GENES IMPLICATED THE OCCURRENCE OF MULTIPLE LOCI IN RICE

The genes AldP and AldC-a, encoding the rice chloroplastic (cp) and cy toplasmic (ct) types of aldolase, respectively, were isolated and sequ enced, and their transcription start points (tsp) were determined. Org anization of the two genes was found to differ greatly; AldP consisted of six exons while AldC-a consisted of two exons. The deduced amino a cid (aa) sequence of AMP contained a cp stromal targeting signal, foll owed by a sequence that matches the experimentally determined N-termin al sequence of mature AldP. The two enzymes share only 55% aa identity . However, rice AldP had about 73% homology with the cp aldolase of sp inach. Also, the homology of AldC-a with maize, spinach and Arabidopsi s thaliana cytoplasmic aldolases ranged from 70 to 90%. Southern blot analyses indicated that AldP is encoded at a single locus, whereas the gene encoding the ct counterpart is distributed at three loci on the genome. This feature is quite different from those of maize and spinac h, in which only one locus was found for the ct aldolase.