Isolation of cDNAs encoding the pyruvate dehydrogenase and citrate synthase from tomato

Abstract

Two cDNAs encoding pyruvate dehydrogenas(PD) and citrate synthase(CS) related to citrate were isolated and characterized from tomato plants. Two clones PD, CS were 1416 bp and 1176 bp, respectively and had a open reading frames(ORF), deriving 52kDa and 43kDap olypeptide. The identities between the deduced amino acid sequences of tomato CS and potato CS were 98%. For PD of tomato and potato same identities (98%) were shown. Genomic DNA blot analysis suggests that MD,PD and CS may be single copy genes. The high est expression of PD, CS and MD (malate dehydrogenase) occurred in roots and MD, PD and CS were expressed in fruit at all developmental stages, and their expression levels were relatively similar. The present study suggests that the expression of TCA cycle was not uniform in the different tissues of the tomato. Although mitochondrial citrate synthase and pyruvate dehydrogenase are usually described as a housekeeping enzyme, its expression is developmentally regulated, indicating that in certain tissues or under certain environmental conditions a higher amount of the enzyme is required.