Characterizing Gene Responses to Drought Stress in Fourwing Saltbush [Atriplex canescens (Pursh.) Nutt.]

Abstract

New techniques in molecular biology can be used to characterize genes whose expression is induced by drought stress. These techniques can be used to understand responses of range plants to environmental stresses at the biochemical and mokcuiar level. For example, they can be used to characterize genes that respond to drought stress conditions in the native shrub Atriplex canesctws (Pursh.) Nutt. Complementary DNA (cDNA) libraries constructed from drought-induced messenger RNA (poly A+ RNA) were used to characterize genes which are associated with the stress response. A cDNA library from A. cunescens was prepared. This library from stressed shrubs was differentially screened with radiolabeled cDNA probes from stressed and nonstressed shrubs, and apparent drought-induced clones were identified. This is the first report of molecular characterization of drought responsive genes in fourwing saltbush. The identification of genes specific to responses to drought stress could provide a basis for understanding drought tolerance in this important range species.

cDNAs induced by ozone from Atriplex canescens (saltbush) and their response to sulfur dioxide and water‐deficit

“…However, these clones showed no similarity to ozone exposure and water-deficit stress are prolonged, the water-deficit-stress-induced Atriplex genes that we The most water-deficit-stressed shrub had a water potenhave previously identified (Chen et al 1996). Their ex-tial of- water-deficit-responsive genes in Atriplex (Adair et al 1992; L. S. Adair, J. Cairney and R. J. Newton, unpublished data), but it is well below the -2.0 MPa to -3.0 MPa which Atriplex can withstand. In contrast, the ozone and SO2 treatments were quite severe (Heck et al 1988).…”

“…Replicate filters of the stressed cDNA library were obtained according to procedures of Adair et al (1992). One duplicate filter was probed with cDNA generated from RNA from ozone-stressed shrubs and the other probed with cDNA from nonstressed shrubs according to procedures established in our laboratory (Adair et al 1992). Clones showing apparent induction were isolated, subjected to a second round of selection, and then isolated as "phagemids" (Stratagene).…”

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

“…Preparation and differential screening of cDNA library A cDNA librarj' was constructed from poiy(A)* RNA isolated from water deficit stressed leaf tisstte using the Stratagene Lambda Zap cDNA synthesis kit (Stratagene, Inc, LaJolla, CA, USA). A cDNA library, with a modal insert size of 1 kb, was constructed from the leaves of field-grown Atriplex with a water potential of -0,94 MPa (Adair et al, 1992). Plaques that hybridized to a first-strand cDN.A probe made from RNA extracted fi"om shrubs stressed by water deficit, but not to a firststrand cDNA probe made from irrigated shrubs, were selected and purified to homogeneity by two further rounds of plaque screening.…”

“…The two cDNA clone,s (pl9-3 and p27-3) which were isolated by differential screeoing of an Atriplex cDNA library (Adair et al 1992) were sequenced. The nucleotide sequence of the coding strand of each cDNA and the deduced amino acid sequence are shown in Fig.…”