PLANT PHYSIOLOGY , Vol 101, Issue 2 683-687, Copyright © 1993 by American Society of Plant Biologists
Cytosolic Triosephosphate Isomerase Is a Single Gene in Rice
Y. Xu and T. C. Hall
Institute of Developmental and Molecular Biology, Texas A&M University, College Station, Texas 77843-3155
A cDNA clone encoding rice (Oryza sativa L.) cytosolic triose-phosphate
isomerase (TPI), an important glycolytic enzyme, was isolated and
characterized. The clone (pRTPI-6) contains an open reading frame of 759
base pairs, encoding a polypeptide chain of 253 amino acid residues (Mr
27,060).The identity of this clone was defined by its high homology (85%
nucleotide sequence and 89% amino acid sequence identical match) with a
maize mRNA sequence encoding the cytosolic TPI and with TPIs from other
species. Genomic DNA blot analysis using the cDNA as a probe showed that
the cytosolic TPI gene is present as a single copy per haploid rice genome,
as opposed to that found in maize, in which multiple TPI gene copies exist.
A single TPI mRNA species of about 1100 nucleotides was detected by gel
blot hybridization analysis of RNA isolated from root, culm, and leaf
tissues, indicating that its expression is ubiquitous. Based on sequence
comparison and molecular analysis, we propose that the chloroplast-located
TPI may be encoded by divergent structural nuclear genes in rice.