Stress-Related Proteins Are Specifically Expressed under Non-Stress Conditions in the Overwinter Buds of the Gentian Plant Gentiana triflora

Abstract

The overwinter bud of the gentian plant, Gentiana triflora, is an organ that develops from the basal tuber in late spring and becomes dormant and freezing-tolerant for overwintering. Here, proteins specifically enriched in the overwinter buds were identified using two-dimensional polyacrylamide gel electrophoresis followed by amino acid sequencing. Enriched proteins included those so far identified as stress-and cold-inducible in other plants, i.e., two isoforms of ethylene-induced esterase, a dehydration-induced protein, glyoxalase I, thioredoxin peroxidase, two isoforms of ascorbate peroxidase and a membrane pore protein. Interestingly, the stress-related proteins had already accumulated in the overwinter buds under non-stress conditions in early summer. Accumulation of these proteins was also examined in a mutant gentian, which developed overwinter buds but lacked cold tolerance and died under conditions below 3°C. In this mutant, several proteins including one of the putative esterase, enolase and ascorbate peroxidase were absent or greatly decreased. Thus, it appears that these stress-related proteins are expressed under non-stress conditions to aquire cold tolerance before overwintering.

Proteomic Study of Low-Temperature Responses in Strawberry Cultivars (Fragaria×ananassa) That Differ in Cold Tolerance

“…First, 'Jonsok', is poised for tolerating cold stress (Supplemental Table S2), and this is contributed by proteins related to freezing/cold tolerance that are constitutively expressed at significantly elevated levels than those in 'Frida'. This poise has been observed in other species (Taji et al, 2004;Takahashi et al, 2006). We speculate the elevated levels of enolase in 'Jonsok', may contribute to this physiological stress poise.…”

“…Sengana' at 42 d (1.7-fold) but it was not cold induced in 'Jonsok'. However, enolase levels, prior to cold acclimation, have been reported to correlate with increased freezing tolerance (Takahashi et al, 2006). Three of the four distinct HSPs that were identified by 2DE exhibited a significant cold induction in 'Frida' (spot 812, 813, 1819), yet 'Jonsok' had greater overall levels at all time points except for spot 812 at 42 d, due to the significant induction in 'Frida'.…”

“…Cold acclimation is known to induce proteins relevant for freezing survival Thomashow, 2010); however, it is plausible that some proteins associated with cold tolerance are expressed under nonstress conditions, i.e. are not cold inducible (Takahashi et al, 2006). Novel insights into the most efficient freezingtolerant mechanisms are expected to be gained from comparing closely related plants that differ in freezing tolerance.…”

High concentrations of sucrose induce overwintering bud formation in gentian plantlets cultured in vitro

“…OWBs accumulate several stress-related enzymes and proteins such as thioredoxin peroxidase (TPX), ascorbate peroxidase (APX), and dehydrin (DHN) (Takahashi et al 2006). We examined the protein profiles of IOWBs and leaves of gentian plantlets as well as of field-grown plants using 2D-PAGE ( Figure 3A-D).…”

“…These five spots were analyzed by LC-MS/MS and identified as highly homologous to late embryogenesis abundant (LEA) protein, enolase, glyoxalase I, TPX I, and putative PR-10 type pathogenesis-related protein, respectively (Table 1). Because homologs of these proteins are related to cold tolerance (Bahramnejad et al 2010;Battaglia et al 2008;Lee et al 2002;Takahashi et al 2006;Veena et al 1999), IOWBs might possess a cold hardiness similar to OWBs. Moreover, transcripts of two gentian DHNs, GtDHN1 (accession no.…”