Isolation, sequence and expression analysis of two water deficit related cDNA clones from the halophyte Atriplex canescens (saltbush)

Abstract

Two homologous cDNA clones (p19-3 and p27-3) of genes induced by water deficit stress were isolated by differential screening of a cDNA library from the desert shrub Atriplex canescens (saltbush). The nucleotide sequences of these clones are nearly identical with 96.5% homology. Both cDNAs contain an open reading frame encoding a small, hydrophilic polypeptide of 95 amino acids with a calculated molecular mass of approximately 11 kDa. The high degree of homology between the two clones may indicate that they are either homologs of one locus or else are derived from two different genes within a multigene family. Under water deficit, these clones were expressed at high levels in leaf, stem and root tissue with the highest expression occurring in stems. Although the level of expression varied among these organs at certain levels of stress, maximum expression occurred with severe water deficits (-1.3 and -2.5 MPa). Although homologous cDNAs have not been isolated from other plants, we demonstrate by Southern blot analysis that homologous sequences are present in rice.