Evolution Styles of Glucose-6-Phosphate Dehydrogenase and 6-Phosphaogluconate Dehydrogenase Genes in Higher Plants

Glucose-6-phosphate dehydrogenase (G6PDH) and 6-phosphaogluconate dehydrogenase (6PGDH) are key enzymes in the plant pentose phosphate pathway. This paper introduces the isolation of two rice cDNAs encoding plastid G6PDH and 6PGDH and describes the analysis of the genes structure, expression profiling and phylogenetic tree of all four G6PDH and 6PGDH genes: OsG6PDH1 for cytosolic G6PDH, OsG6PDH2 for plastid G6PDH, Os6PGDH1 for cytosolic 6PGDH, and Os6PGDH2 for plastid 6PGDH. In higher plants, the distinct evolution styles of G6PDH and 6PGDH reveal that plant cytosolic G6PDH gene may have a common ancestor with animal and fungi, while cytosolic 6PGDH and its plastid isozyme both have an endosymbiotic gene-replacement origin. This paper discusses the possible evolution styles of G6PDH and 6PGDH enzymes and supplies new data on the evolution of higher plants and their plastids.