Characterization of the COS cDNA library. A, Schematic map of the T-DNA region of pER8GW vector. XVE, Chimeric XVE fusion gene, encoding the chimeric transcription activator for the pLexA promoter (Zuo et al., 2000); HPT, hygromycin phosphotransferase gene; pLexA, LexA operator fused to a minimal promoter of the cauliflower mosaic virus 35S gene; attR1 and attR2, Gateway recombination sites; CmR, chloramphenicol resistance gene; ccdB, suicide marker for bacterial contraselection; T, Rubisco rbcsS3A polyA sequence; RB and LB, T-DNA left and right border sequences, respectively; cDNA, randomly inserted cDNA clone; A and B, positions of T-DNA specific PCR primers used for amplification of inserted cDNAs. B, Comparison of size distribution of DNA fragments in the cDNA library and in the database of predicted full-length transcripts at TAIR (http://www.Arabidopsis.org). Fragment sizes are indicated in kilobase pair.