CHARACTERIZATION OF 2 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 libr ary from one-hour-dehydrated plants of Arabidopsis thaliana L. were se quenced and characterized. The predicted ERDIO 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) protei ns, a class of proteins that accumulate late in embryogenesis and whos e gene expression is induced by the plant hormone abscisic acid (ABA). Genomic Southern blot analysis suggested the existence of an ERD10-re lated gene. The expression of the genes that correspond to ERD10 and E RD14 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 expre ssion of both the erd10 and erd14 genes revealed a two-step induction process. Early induction occurred within 1 h and secondary induction o ccurred 5 h after the beginning of cold stress. Application of ABA ind uced the expression of both genes, but application of 2,4-D, BA, ABA a nd GA3 did not affect the expression of these genes. In bolting plants , both ERD10 and ERD14 transcripts were detected in stems, cauline lea ves, roots and flowers, but their levels decreased during seed formati on and only low levels of the transcripts were detected in seeds at th e late-mature stage.