Triose phosphate isomerase of Stellaria longipes (Caryophyllaceae)

A cDNA encoding triose phosphate isomerase (TPI) of Stellaria longipes has been isolated and sequenced. The TPI of S. longipes exhibits high similarity to the TPIs from other species at both the nucleotide and amino acid levels. Southern blot analysis showed that the S. longipes genome contained multiple TPI-like nucleotide sequences and only a low degree of polymorphism was observed among genotypes of different habitats. The levels of TPI mRNA, detected by hybridization to the TPI cDNA, appeared similar between the genotypes. However, different genotypes showed variations in the total TPI activity, reflecting the possible ecological effect on the TPI gene expression. Northern blot hybridization to the cDNA also indicated a higher level of TPI mRNA in leaves than in roots, suggesting tissue-specific expression of TPI gene(s). Phylogenetic analysis of the TPI amino acid sequences from 16 taxa suggested that the TPI from S. longipes was more closely related to cytosolic TPIs from other plants than it was to TPIs from prokaryotes.