Characterization of two cDNAs (ERD10 and ERD14) corresponding to genes that respond rapidly to dehydration stress in Arabidopsis thaliana.

Two cDNA clones, designated ERD10 and EDR14, isolated from a cDNA library from one-hour-dehydrated plants of Arabidopsis thaliana L. were sequenced and characterized. The predicted ER10 and ERD14 polypeptides have a compositional bias towards Glu (19.62% and 21.08%, respectively) and Lys (16.15% and 18.38%, respectively) and both lack Trp and Cys residues. The amino acid sequences deduced from of both cDNAs are very similar to those of Group II LEA (late embryogenesis abundant) proteins, a class of proteins that accumulate late in embryogenesis and whose gene expression is induced by the plant hormone abscisic acid (ABA). Genomic Southern blot analysis suggested the existence of an ERD10-related gene. The expression of the genes that correspond to ERD10 and ERD14 was strongly induced in rosette plants of Arabidopsis within 1 h of dehydration and elevated levels of transcripts were detected during 24 h of dehydration. Northern blot analysis of the cold-induced expression of both the erd10 and erd14 genes revealed a two-step induction process. Early induction occurred within 1 h and secondary induction occurred 5 h after the beginning of cold stress. Application of ABA induced the expression of both genes, but application of 2,4-D, BA, ABA and GA3 did not affect the expression of these genes. In bolting plants, both ERD10 and ERD14 transcripts were detected in stems, cauline leaves, roots and flowers, but their levels decreased during seed formation and only low levels of the transcripts were detected in seeds at the late-mature stage.