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

Abstract

Ozone effects on plant water relations have been reported to be similar to those of water‐deficit. The objective was to identify ozone‐inducible (OI) clones from Atriplex canescens (saltbush) and determine if they were also responsive to water‐deficit as well as SO2. cDNA clones derived from four different polyA RNAs which accumulate in 8‐month‐old shrub leaves exposed to ozone (0.2 μl I−1, 6 h day−1, 7 days) were isolated by differential screening, analyzed by northern blots, sequenced, and gene product homologies with other plant genes were determined. Clone OI12A‐3 has homology with wound‐inducible proteinase inhibitors, whereas clone OI8–3 protein is homologous to thiol proteases. Clones OI2–2 and OI14–3 putatively code for glycine‐rich proteins with repeated motifs (Gly‐Gly‐Gly‐Tyr‐Gly‐His)n and putative cell‐wall‐targeting signal peptides. Clone OI2–2 and particularly clone OI14–3 were also induced by both SO2 and water‐deficit. These data indicate that woody plant genes associated with cell wall protein production and whose expression is induced by several stress factors may be responding to common oxidative stress pathways.

The isolation of genes from the resurrection grass Sporobolus stapfianus which are induced during severe drought stress

“…Database searches did not reveal any strong similarity to previously identified genes. However, the S. stapfianus gene product does contain repeat regions rich in glycines and histidines which are similar to those present in the proteins encoded by drought‐inducible genes from saltbush ( No et al 1997 ) and the CORA gene and ABA‐ and environmental stress‐inducible genes from Medicago sativa which are induced by drought and cold ( Luo et al 1992 ; Laberge, Castonguay & Vezina 1993).…”

“…This has led to the suggestion that the GPRP may have a role in vesicle‐associated intracellular transport or in linking cellular components through the plasma membrane with the cell wall ( Marty et al 1996 ). Several studies have proposed that tyrosine residues in repeat regions similar to those occurring in SDG7 and the N‐terminus of SDG43c may be involved in the formation of cross‐links with GRPs and other cell wall components to reduce cell wall elasticity in response to various stresses, including water deficit ( Bradley, Kjellbom & Lamb 1992; Meier et al 1992 ; No et al 1997 ). This presents an attractive hypothesis for a proposed role for the S. stapfianus GPRP in drought tolerance, whereby interaction of the GPRP with the plasma membrane and cell wall may help to maintain the integrity of the cell during dehydration or rehydration.…”

Glycine-rich proteins as structural components of plant cell walls

“…Some GRPs consist almost exclusively of glycine-rich sequences, e.g. ptGRP1, GRP1.8 and GRP1.0 of bean, Os-GRP1 of rice, atGRP-5 of Arabidopsis, GRP-22 of Brassica napus or zmGRP3 of maize [13 -18], whereas others have glycine-rich domains adjacent to domains with lower levels of glycine such as atGRP-3 and atGRP-6 of Arabidopsis, TFM5 of tomato or OI14-3 and OI2-2 of saltbush [16,[19][20][21]. A third group are GRPs that have an increased glycine content but not domains that are particularly glycine-rich.…”

“…Besides developmental regulation, expression of grp genes has been shown to be altered by external influences such as wounding, hormone treatment, low temperature and water or ozone stress [14, 16, 17, 21, 22, 25, 39 -41]. In fact, several grp genes were cloned in differential hybridization experiments performed with the goal to isolate genes induced by drought, water or low-temperature stress [21,25,42]. Thus, GRPs are not only required in certain stages of development but are often also stress-induced proteins.…”

Superoxide generation catalyzed by the ozone-inducible plant peptides analogous to prion octarepeat motif

“…5,6 As one of plant responses to ozone, ozone-inducible (OI) genes have been isolated from saltbush (Atriplex canescens) and their expression was shown to be responsive not only to ozone, but also to other environmental stresses such as SO 2 and water deficit. 7 To date, two isotypes (OI2-2, 119 amino acids and OI14-3, 158 amino acids) of OI peptides have been reported and they possess a common characteristic repeat unit consisting of hexa amino acids, YGHGGG, repeating it for 7-9 times in tandem. Due to the presence of this repeat unit, OI peptides are considered putative members of glycine-rich proteins (GRPs).…”