Identification of Dehydrin-Like Proteins Responsive to Chilling in Floral Buds of Blueberry (Vaccinium, section Cyanococcus)

Abstract

l h e level of three major polypeptides of 65, 60, and 14 kD increased in response to chilling unit accumulation in floral buds of a woody perennial, blueberry (Vaccinium, section Cyanococcus). The level of the polypeptides increased most dramatically within 300 h of chilling and decreased to the prechilling level with the initiation of budbreak. Cold-hardiness levels were assessed for dormant buds of Vaccinium corymbosum and Vaccinium ashei after different chilling treatments until the resumption of growth. lhese levels coincided with the level of the chilling-responsive polypeptides. Like some other previously described cold-induced proteins in annual plants, the level of the chilling-induced polypeptides also increased in leaves in response to cold treatment; the chilling-induced polypeptides were heat stable, resisting aggregation after incubation at 95°C for 15 min. By fradionating bud proteins first by isoelectric point (pl) and then by molecular mass, the p l values of the 65-and 60-kD polypeptides were found to be 7.5 to 8.0 and the p l value of the 14-kD polypeptide was judged to be 8.5. Purification of the 65-and 60-kD polypeptides, followed by digestion with endoproteinase Lys-C and sequencing of seleded fragments, revealed similarities in amino acid composition between the 65-and 60-kD polypeptides and dehydrins. Indeed, antiserum to the lysine-rich consensus sequence EKKCIMDKIKEKLPC of dehydrin proteins cross-reacted to all three of the major chillingresponsive polypeptides of blueberry, identifying these as dehydrins or dehydrin-like proteins.

Current state of cold hardiness research on fruit crops

“…In floral buds of Bluecrop and Tifblue blueberries, chillingresponsive 65-, 60-, and 14-kDa polypeptides which were identified as dehydrins or dehydrin like proteins, accumulated during cold acclimation (Muthalif and Rowland 1994). The largest increase in the level of polypeptides occurred at the same time as the largest increase in the level of cold hardiness.…”

Purification and Characterization of the Acid Soluble 26-kDa Polypeptide from Soybean Seeds

“…Since many LEA proteins including dehydrin group proteins have been reported to resist denaturation by heat treatments of95 to 100°C,1l.17 20) heat stability of purified AS26k, and polypeptides in the whey fraction was investigated. As shown in Fig.…”

Molecular responses to thermal stress in woody plants

“…Cryoprotective and antifreeze activity has also been reported for a peach DHN , and Puhakainen et al (2004) have shown that overexpression of multiple dehydrin genes enhances tolerance in freezing stress in Arabidopsis. Woody plants accumulate DHN during periods of cold acclimation in leaves, buds and bark, and the presence of these proteins is correlated with increased freeze tolerance (Arora and Wisniewski, 1994;Muthalif and Rowland, 1994;Cai et al, 1995;Welling et al, 1997;Rinne et al, 1999;Núñez, 2003;Karlson et al, 2003). In addition, seasonal dehydrin fluctuations have been observed in the xylem of multiple woody species.…”