Drought-stimulated genes correlated with desiccation tolerance of the resurrection grass Sporobolus stapfianus

Abstract

In order to identify genes involved in expression of desiccation tolerance in the foliage of the grass Sporobolus stapfianus, a cDNA library was constructed from desiccated leaf tissue of S. stapfianus. Differential screening resulted in the isolation of a number of clones which detect transcripts whose abundance alters during drought stress and the associated induction of desiccation tolerance. The characteristics of 6 of these cDNA clones are presented here. Transcripts represented by three of the cDNA clones accumulate during drying and following treatment of leaves with abscisic acid (ABA). A fourth cDNA clone detects a transcript which also accumulates following application of ABA but the transcript level fluctuates during drying. The remaining two cDNA clones are not responsive to ABA but transcript levels are present throughout the drying process. Characterisation of these cDNAs has led to the identification of the encoded proteins. Some have similarity to proteins which are known to be involved in the protection of cellular organelles and detoxification processes and they include dehydrin, LEA group 3 and thiol proteases which have been identified in other systems and shown to be induced by water stress. In addition one clone showed similarity to glyoxalase I, an enzyme involved in the removal of toxic byproducts produced during glycolysis, which has been shown to be induced by salt stress in tomato.