Full TGIF Record # 270886
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Content Type:Abstract or summary only
Author(s):DaCosta, Michelle; Hoffman, Lindsey; Guan, Xian; Ebdon, Scott
Author Affiliation:DaCosta, Guan, and Ebdon: Stockbridge School of Agriculture, University of Massachusetts, Amherst, MA; Hoffman: Department of Plant Biology and Pathology, Rutgers University, New Brunswick, NJ
Title:Physiology of cold acclimation and deacclimation in cool-season turfgrasses
Source:Bioforsk Fokus. Vol. 9, No. 8, 2014, p. 8-9.
# of Pages:2
Publishing Information:[Norway]: Bioforsk
Keywords:TIC Keywords: Agrostis stolonifera; Cold acclimation; Cool season turfgrasses; Cultivar evaluation; Deacclimation; Gene expression; Lolium perenne; Metabolism; Physiological responses; Plant growth regulators; Poa annua; Protein metabolism; Temperature response; Winter injury
Abstract/Contents:"Increases in soil and air soil temperatures during the overwintering period may trigger metabolic and physiological changes leading to cold deacclimation and loss of freezing tolerance in cool-season turfgrasses. Elevated temperatures followed by freezing events can result in increased sensitivity of grasses to direct low temperature kill, particularly for species such as annual bluegrass (Poa annua L) and perennial ryegrass (Lolium perenne L.). Additional research is necessary to understand the factors that trigger deacclimation in grasses and to identify plant traits that contribute to enhanced deacclimation resistance and freezing tolerance. The specific objectives of our research were to determine the effects of different above-freezing temperature and duration combinations that induce deacclimation of annual bluegrass (AB) and creeping bentgrass (CB), and to examine early physiological changes associated with deacclimation of these two species, with a focus on carbohydrate, protein, and hormone metabolism parameters. Additional studies were also undertaken to study deacclimation responses in perennial ryegrass (PR), with a focus on identifying genes that may be differentially expressed between genotypes of PR contrasting in freezing tolerance and deacclimation resistance. In our initial studies, we compared one AB ecotype (previously shown to exhibit freezing sensitivity) and one CB cultivar ('L-93'). Plants were exposed to a cold acclimation at 2°C followed by -2°C in controlled environment chambers. The grasses were then exposed to deacclimation treatments that consisted of warming the chambers until the soil temperatures reached 4°C, 8°C, or 12°C for up to 5 days at each temperature. In all the experiments, we found that annual bluegrass never achieved the same level of freezing tolerance as creeping bentgrass in response to cold acclimation, determined as the lethal temperature at which 50% of plants were killed (LT50). Along with a lower cold acclimation capacity, AB exhibited a 2.5-fold greater loss in freezing tolerance in response to exposure at 4°C. Conversely, at later stages of deacclimation and greater warming, CB also exhibited significant deacclimation and loss in freezing tolerance. Therefore, although both AB and CB exhibited deacclimation in response to above freezing temperatures, the threshold temperature required to induce greater losses in freezing tolerance was lower for AB compared to CB. In subsequent experiments, we monitored changes in carbohydrate metabolism in response to exposure to simulated mid-winter warming events. We found AB leaves were greener and had higher water content compared to CB when exposed to deacclimating temperatures. In addition, photosynthesis and respiration rates increased very rapidly during deacclimation for AB, suggesting that metabolic and physiological activities of AB were activated earlier in response to warmer temperatures compared to CB. We next compared creeping bentgrass ('L-93') to one freezing-tolerant AB ecotype (AB-T) and one freezing-sensitive AB ecotype (AB-S). Following cold acclimation, plants were exposed to 8°C for 0.5, 1, 3, and 5 d to induce deacclimation. At each duration of deacclimation, plants were assessed for their freezing tolerance (LT50), concentrations of soluble sugars and amino acids, and changes in dehydrin-like proteins in overwintering crowns. Fully acclimated CB achieved a higher freezing tolerance (LT50 of -21.5°C) compared to AB-T (-19.8°C), followed by AB-S (-15.3°C). Total soluble sugars, mainly high molecular weight (HMW) fructans, increased during cold acclimation for all plants, with higher levels accumulated in CB. Dehydrin-like proteins were present in each species, but were cold-inducible and associated with freezing tolerance changes only in CB. In response to deacclimation, CB maintained higher freezing tolerance compared to both AB ecotypes, which was associated with the maintenance of higher concentrations of total soluble sugars, and in particular the HMW fructans. Lastly, our most recent studies have also helped us to identify differences in the signaling of plant hormones during cold acclimation and deacclimation, such as auxins and abscisic acid, which are further being investigated within our research group."
See Also:See also related thesis, Physiology of Cold Acclimation and Deacclimation Responses of Cool-Season Grasses: Carbon and Hormone Metabolism, 2014, R=307690. R=307690
Note:This item is an abstract only!
ASA/CSSA/SSSA Citation (Crop Science-Like - may be incomplete):
DaCosta, M., L. Hoffman, X. Guan, and S. Ebdon. 2014. Physiology of cold acclimation and deacclimation in cool-season turfgrasses. Bioforsk Fokus. 9(8):p. 8-9.
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