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This study was conducted to determine if changes in the raffinose: sucrose ratio in embryos of shrunken-2 sweet corn (Zea mays L.) hybrids were related to differences in seed leachate conductivity between two hybrids harvested at four maturities and artificially dried to 0.10 g H2O/g fresh weight. The ratio of raffinose: sucrose differed for `Crisp N' Sweet 710' (CNS) and `How Sweet It Is' (HSII). The mass ratio of raffinose: sucrose in CNS was >0.3 in seed harvested between 0.44 to 0.64 g H2O/g fresh weight and increased as seed dried from the initial harvest moisture to 0.10 g H2O/g fresh weight. Raffinose: sucrose ratios of HSII were <0.3 at all harvests between 0.55 to 0.72 g H2O/g fresh weight, but changes during desiccation were not as pronounced. Leachate conductivity of whole seeds of CNS and HSII decreased as seeds were harvested at progressively lower moisture contents. We suggest that a higher raffinose: sucrose ratio may be indicative of increased seed vigor in shrunken-2 hybrids.

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Woody plants can be induced to cold-acclimate by exposure to sublethal low temperatures, but only after the onset of vegetative maturity. We monitored seven woody plant taxa, at monthly intervals, to determine the date of vegetative maturity, freeze-killing temperature, cell membrane electrolyte leakage, and the quantity and diversity of endogenous oligosaccharides. The freeze-killing temperature changed from -5 to -7C before vegetative maturity to -15 to -20C after vegetative maturity. There was a 10-fold increase in raffinose and about a 3-fold increase in endogenous stachyose in samples that were cold-acclimated under controlled conditions. In field samples, endogenous raffinose increased from <0.02% in August to 2% to 11% in cortical stem tissues of all cold-acclimated taxa. The tetrasaccharide stachyose increased from <0.02% to 0.25% to 2.5% for similar comparisons. None of the other sugars or polyols showed similar, consistent patterns during the onset of cold acclimation. In response to low temperature, raffinose family oligosaccharides (RFOs) have previously been shown to increase substantially in cabbage, soybean, kidney bean, and Chlorella. RFOs also possess high water-binding characteristics and tend to enhance aqueous glass transitions. Accordingly, we hypothesize that the endogenous production of these oligosaccharides may play an important role in metabolic events associated with cryoprotection of critical cellular functions during low-temperature stress.

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(250 mm × 4 mm i.d.) at a flow rate of 0.5 mL·min −1 . The mobile phase was distilled water. The detection was accomplished using a RI2414 detector. Commercial sugars, including glucose, fructose, sucrose, raffinose, and stachyose, purchased from Sigma

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Various carbohydrates have been shown to be associated with stress tolerance in some plant species. Specifically, the content of soluble sugars have been correlated with desiccation tolerance and winter hardiness. We have previously demonstrated that radicles of cucumber seed become progressively more sensitive to chilling injury during the early stages of germination and that cultivar differences exist. Sucrose, raffinose, and stachyose contents of `Poinsett 76' and `Ashley' seed were determined in dry seed during imbibition and at three stages of radicle emergence. The more chilling-tolerant cultivar (Ashley) contained lower raffinose and higher stachyose contents than the less chilling-tolerant `Poinsett 76'. In both cultivars, the contents of raffinose and stachyose declined dramatically between the 1-mm and 5- to 7-mm stage of radicle emergence. At the 1-mm stage, when cultivar chilling-tolerance differences are most pronounced, `Ashley' appears to have a higher content of stachyose and lower raffinose content.

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[retention time (RT) = 7.0 min, fructose (RT = 7.6 min), sorbitol (RT = 8.4 min), glucose (RT = 9.0 min), sucrose (RT = 10.5 min), raffinose (RT = 13.7 min), and stachyose (RT = 16.6 min)] based on the same retention times exhibited by both pure and mixed

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Spinach (Spinacia oleracea, L. cv. `Ark88-354'. `Fall Green', `Cascade') seeds of varying sensitivities to high temperatures during imbibition and germination were subjected to constant 18, 30 and 36°C for 96 hours during imbibition. Those cultivars less sensitive to high temperatures (`Ark88-354' and `Fall Green') imbibed water more rapidly at higher temperatures and had greater initial levels of raffinose and sucrose than the sensitive cultivar `Cascade'. Glucose levels were initially zero in all cultivars and increased slightly with time. Germination was more rapid at 18°C and 30°C in `Ark88-354' and `Fall Green' than with `Cascade'; the latter also failed 10 germinate at the higher temperature. Raffinose and sucrose have been implicated in membrane stabilization during desiccation and extreme low temperatures. They may serve a similar role during imbibition and germination of spinach at high temperatures, reducing secondary thermodormancy.

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Twenty-five cultivars were initially screened for germination at 10 °C, 30 °C, and 40 °C. Four cultivars were chosen for further study for physiological and biochemical characteristics—namely, `Texas Cream 40' (TC-40), which showed ability to germinate at very high (40 °C) and low (10 °C) temperatures; `Black Crowder' (BC), which had acceptably high germination at 40 °C, but reduced germination at 10 °C; and `Mississippi Purple' (MP), which exhibited lower germination at all temperatures tested. The main sugars present in cowpea seed were sucrose, raffinose, and stachyose. Sugar contents were affected by cultivar, type of tissue, and temperature. Sucrose contents were higher in embryo tissue of cultivars with a lower germination percentage, and reduced in the cultivar with a higher germination percentage, suggesting the use of sucrose for germination. Sucrose decreased greatly at 30 °C and increased again at 40 °C. Sucrose “de novo” synthesis was higher at higher temperature. An accumulation of sucrose was evident in embryo tissues of cultivars with reduced ability to germinate at low temperature. Raffinose and stachyose contents were higher in ungerminated seed. In germinated seed, raffinose and stachyose contents were found only in cotyledon tissues at 10 °C. The peroxidase activity was affected by cultivars, type of tissue, and temperature. The highest peroxidase activity was found at low temperature (10 °C) in embryo tissue of the cultivar with the highest germination. The result also suggests that high peroxidase activity was related to ability of seed to germinate at low temperature.

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Decreasing photoperiods and decreasing temperatures induce cold acclimation and the accumulation of soluble sugars in many plants. Two cultivars of southern magnolia differing in cold hardiness and acclimation patterns, were monitored to determine photoperiod × temperature interaction on cold hardiness and soluble sugar content. Cold hardiness increased with low temperatures and short photoperiods. Total soluble sugars, sucrose, and raffinose consistently increased in the leaves and stems of both cultivars in response primarily to low temperature. `Little Gem' was less responsive to photoperiod than `Claudia Wannamaker'

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Strawberry plantlets, regenerated from leaf disks, were used as a model system to study the effect of high concentrations of sugars and dehydration on survival during cryopreservation. After cold acclimation, plantlets imbibed for 3 days (one day each) in 0.5, 0.7 and 1.2 M sucrose and (1.0M sucrose + 0.2M raffinose) and desiccated to 25 % moisture (fwb) in alginate capsules consistently survived cryopreservation. Differential scanning calorimetry revealed only a very small exotherm between -20C and -28C during freezing; a glass transition at -50C and a small melting event at -10C during warming. Conversely, samples with the lowest survival rate, had a large nucleation exotherm at -30C and a devitrification exotherm between -70 and -40C. We conclude that imbibition with sugars, coupled with desiccation treatments, may be used to manipulate freeze tender tissues of strawberry to permit successful cryopreservation.

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Aqueous fractions in dormant buds of Amelanchier alnifolia Nutt. `Smoky', may exist either as liquid, ice or glass phases depending on the temperature history and the water content of the tissue. Phase diagrams for these states were constructed from differential scanning calorimetry (DSC) freezing and warming scans. The diagrams show that glass transition temperatures shift to warmer temperatures as cold hardening increases and as the water content is lowered by controlled desiccation. Glass transitions were detected from -60 to -20° C, during slow freezing scans in the DSC, suggesting that survival of this extremely cold hardy tissue is based upon a potential to undergo glass transitions in the dormant state. Endogenous raffinose family oligosaccharides (RFO) increase during cold hardening, and decrease as hardiness diminishes with the onset of growth.

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