Molecular characterization of pdc2 and mapping of three pdc genes from rice

The anaerobic fermentation pathway is thought to play an important role under flooding conditions. The pyruvate decarboxylase 2 (pdc2) gene that encodes the first enzyme of this pathway has been cloned and characterized from rice. This gene has an open reading frame that putatively encodes a 603 amino-acid-residue protein with a molecular mass of 64 kDa. pdc2 has five introns dispersed throughout the coding region, which is also true for rice pdc1. Although the length of these introns in rice pdc2 are different from those in rice pdc1, they are located in exactly the same positions based on the deduced amino-acid sequences. The temporal and spatial expression patterns of pdc1 and pdc2 show that pdc2 is induced to a higher level during the early period (1.5–12 h) of anoxia than pdc1, which is induced more after longer time periods (24–72 h) of anoxia in both shoots and roots. The map positions of the three pdc genes have also been determined. Rice pdc1 is located on chromosome 5 between BCD454A and RZ67, pdc2 is located on chromosome 3 between RZ329 and RZ313, and pdc3 is mapped on chromosome 7 distal to RG351.