Molecular Cloning of Abscisic Acid-Responsive mRNAs Expressed during the Induction of Freezing Tolerance in Bromegrass (Bromus inermis Leyss) Suspension Culture

Abstract

Abscisic acid (ABA) increases the freezing tolerance of bromegrass (Bromus inermis Leyss) cell-suspension cultures at 23'C and elicits many metabolic changes similar to those observed during cold acclimation. lnduction and maintenance of freezing tolerance by ABA is accompanied by the expression of novel polypeptides and translatable RNAs. l h e objective of this study was to isolate and characterize ABA-responsive cDNAs associated with ABAinduced freezing tolerance in bromegrass cell cultures. Among the 16 ABA-responsive cDNA clones isolated, 9 were expressed only with ABA treatment, 7 showed increased transcript level, and 1 was transiently expressed. Cold responsiveness was determined in three clones with increased transcript levels and in the transiently expressed clone. Deacclimation of ABA-hardened cells was a relatively slow process, because all of the novel transcripts persisted for at least 7 d after cells were cultured in ABA-free medium.Preliminary sequencing of cDNAs has identified several clones that share high sequence homology with genes associated with sugar metabolism, osmotic stress, and protease activity. Clone pBCA61 was fully sequenced and tentatively identified as an NADPHdependent aldose reductase. l h e predicted amino acid sequence of the coding region shared 92% similarity with that predicted for barley aldose reductase cDNA. It is proposed that expression of genes related to sugar metabolism and osmotic stress may be required for ABA-induced hardening.

A Rapeseed Cold-Inducible Transcript Encodes a Phosphoenolpyruvate Carboxykinase

“…Therefore, the accumulation of Glc or Sue synthesized from the phosphorylated form of Glc might function as a cryoprotectant in plants exhibiting cold hardiness. In agreement with our results, the up-regulation of aldose reductase and phosphoglucomutase in bromegrass (Lee and Chen, 1993) and Sue synthase in wheat (Crespi et al, 1991) indicates that there is a requirement for genes involved in sugar metabolism during cold acclimation. Whether these changes are biologically significant for the acclimation process or are simply a consequence of adaptation remains to be determined.…”

Effects of Abscisic Acid Metabolites and Analogs on Freezing Tolerance and Gene Expression in Bromegrass (Bromus inermis Leyss) Cell Cultures

“…These observations are consistent with the report of Tanino et al (1990), who demonstrated using the same cell culture that (±)-ABA treatment increased Sue uptake. Also, studies using the same culture have shown that (±)-ABA treatment results in the increased expression of genes associated with sugar metabolism (Lee and Chen, 1993). Sue also enhances the freezing tolerance of (±)-ABA-treated bromegrass suspension cultures (Reaney, 1989;Ishikawa et al, 1990).…”

Cold Acclimation in Genetically Related (Sibling) Deciduous and Evergreen Peach (Prunus persica [L.] Batsch) (II. A 60-Kilodalton Bark Protein in Cold-Acclimated Tissues of Peach Is Heat Stable and Related to the Dehydrin Family of Proteins)

“…Although considerable effort has been directed at understanding the structure and function of these proteins in herbaceous plant species (Volger and Heber, 1975; Guy and Haskell, 1989;Hincha and Schmitt, 1992;Houde et al, 1992;Lin and Thomashow, 1992a;Lee and Chen, 1993), reports concerning deciduous fruit trees and woody plants, in general, are limited. Determining whether or not seasonal changes in protein turnover are specifically associated with cold acclimation is difficult because of the fact that overwintering deciduous perennials also enter into endodormancy during the same time as they develop cold hardiness.…”