Functional analysis of the members of Arabidopsis NAC transcription factors controlling the expression of the ERD1 gene under drought stress

Abstract

Previous experiments have established that the MYC-like sequence CATGTG plays an important role for induction of dehydration-dependent expression of the ERD1 gene that encodes a putative protein similar to the ATP binding subunit of the Clp protease. Three cDNA clones encoding NAC proteins that bind to the 63-bp fragment of the ERD1 promoter containing the CATGTG motif were isolated using yeast one-hybrid system. The cDNA clones were named NAC2, NAC3 and NAC4. The three encoded proteins formed a subgroup of the NAC transcription factor. All three proteins bound specifically to the CATGTG motif either in vitro or in vivo, and activated the transcription of the GUS reporter gene driven by the 63-bp fragment in Arabidopsis protoplasts. Expression of the three genes was induced mainly by drought, high salinity stress and ABA treatment, but not by low temperature. Using yeast one-hybrid system we determined the complete NAC recognition sequence (NACRS).