Abstract: Based on the previous study, we cloned the full length cDNA sequence of serine/threonine protein phosphatase 2C (PP2C) by electronic cloning and reverse transcription PCR, assayed its expression difference and enzyme activity among different inbred lines under drought stress by fluorescence quantitative real-time PCR and non-radioactive labeled method respectively, and analysed the relationships between the enzyme activity and drought tolerance in maize. The result indicated that the full length cDNA sequence we cloned is a new member of PP2C gene family in maize, and its open reading frame of 1 164 bp encodes 388 amino acid residues. This gene was denominated as ZmPP2Ca and registered at GenBank (accession number: EF195257). Under drought stress, its down-regulated expression decreased enzyme activity of PP2C in drought-tolerant inbred lines, and its up-regulated expression increased enzyme activity of PP2C in drought-sensitive inbred lines. The differential expression of gene ZmPP2Ca and difference of PP2C activity are speculated to be implicated in signal transduction in maize cells under drought stress.

Key words: Maize, Serine/threonine protein phosphatase, PP2C, Drought tolerance