DROUGHT-STIMULATED GENES CORRELATED WITH DESICCATION TOLERANCE OF THERESURRECTION GRASS SPOROBOLUS-STAPFIANUS

In order to identify genes involved in expression of desiccation toler ance in the foliage of the grass Sporobolus stapfianus, a cDNA library was constructed from desiccated leaf tissue of S. stapfianus. Differe ntial screening resulted in the isolation of a number of clones which detect transcripts whose abundance alters during drought stress and th e associated induction of desiccation tolerance. The characteristics o f 6 of these cDNA clones are presented here. Transcripts represented b y three of the cDNA clones accumulate during drying and following trea tment of leaves with abscisic acid (ABA). A fourth cDNA clone detects a transcript which also accumulates following application of ABA but t he transcript level fluctuates during drying. The remaining two cDNA c lones are not responsive to ABA but transcript levels are present thro ughout the drying process. Characterisation of these cDNAs has led to the identification of the encoded proteins. Some have similarity to pr oteins which are known to be involved in the protection of cellular or ganelles and detoxification processes and they include dehydrin, LEA g roup 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 toxi c byproducts produced during glycolysis, which has been shown to be in duced by salt stress in tomato.