Dehydration of Dormant Apple Buds at Different Stages of Cold Acclimation to Induce Cryopreservability in Different Cultivars (original) (raw)
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Canadian Journal of Plant Science, 1988
The survival of dormant, vegetative apple buds frozen to −30 °C or −40 °C for 5 min or 24 h prior to immersion in liquid nitrogen was investigated for 15 apple cultivars. Although survival after immersion in liquid nitrogen was optimum for the majority of cultivars when prefrozen to −30 °C for 24 h, some cultivars had low survival regardless of the prefreezing treatment. For these cultivars, survival was improved if the tissue was dehydrated prior to prefreezing.Key words: Malus domestica Borkh., apple freezing, moisture content, cold hardiness
Cryo letters
In a continuing study to improve the efficiency of dormant bud cryopreservation for tissues hardened in maritime climates, the water status of dormant buds was monitored between -4 degree C and recovery from liquid nitrogen (LN). Measurement of water content, simple thermal analysis and differential scanning calorimetry were employed. Buds did not lose water during cooling to, or holding at -30 degree C indicating that cryodehydration and/or other adaptive responses contributed during this essential step. A bud exotherm that was an artefact of warming was detected due to necessary handling at -4 degree C before cooling to -30 degree C. There were no significant differences between cultivars with respect to water status at -30 degree C or immediately upon rewarming from LN despite significant differences in post-LN survival. Buds rehydrated in 5 days, but up to 14 days may be needed for recovery for some cultivars. In some instances buds could be grafted without rehydration, taking u...
Freezing of Water in Dormant Vegetative Apple Buds in Relation to Cryopreservation
PLANT PHYSIOLOGY, 1988
Various empirical prefreezing protocols have been used to facilitate cryopreservation of dormant buds from woody plants. The objective of this research was to determine the quantity of water remaining in liquid phase, under different prefreezing conditions using pulsed nuclear magnetic resonance spectroscopy of dormant apple (Malus domestica Mill.) buds from three cultivars. During prefreezing, the quantity of water remaining in the liquid phase was less at-40C<-30°C<-20°C for all cultivars tested. The prefreezing temperature had a greater influence on reducing the quantity of liquid water than the duration of prefreezing. Prefreezing to-40°C for 24 hours was optimal for 'Patterson' and 'McIntosh,' the hardiest cultivars, compared to-30°C for 24 hours with 'Red Delicious.' Cryopreservation of dormant apple buds depends upon the quantity of liquid water during prefreezing, prior to immersion in liquid nitrogen, and upon the cultivar.
Cryotolerance of apple tree bud is independent of endodormancy
Frontiers in Plant Science, 2015
Increasing interest in cryopreservation of dormant buds reveals the need for better understanding of the role of dormancy in cryotolerance. Dormancy stage and lowtemperature survival of vegetative apple buds (Malus domestica Borkh.), cultivars 'Sampion' and 'Spartan', collected from orchard were evaluated during three seasons contrasting in temperature and precipitation throughout the arrested plant growth period. During each season, the cultivars differed either in the onset of the endodormancy or in the length of the endodormant period. A simple relation between endodormancy of the buds and their water content was not detected. The cryosurvival of vegetative apple buds of both cultivars correlated with their cold hardening without direct regard to their particular phase of dormancy. The period of the highest bud cryotolerance after low-temperature exposure overlapped with the endodormant period in some evaluated seasons. Both cultivars had the highest cryosurvival in December and January. The presented data were compared with our previous results from a dormancy study of in vitro apple culture. Endodormancy coincided with the period of successful cryosurvival of apple buds after liquid nitrogen exposure, but as such, it was not decisive for their survival and did not limit their successful cryopreservation.
Dormant Bud Cryopreservation: Secondary Buds Can Affect the Estimation of Post-Thaw Survival
Acta Horticulturae, 2011
Dormant, winter bud cryopreservation is an effective ex situ technique for genetic conservation that does not require resource-intensive in vitro facilities, opening opportunities for many field-based organisations. A protocol for Malus (apple) developed in the continental climate of N. America was employed, with variable success in the maritime climate of Denmark. During the initial, extended-4°C incubation, a single freezing event occurred within the buds, enabling cryodehydration. Bulk tissue water loss also occurred. During subsequent cooling to-30°C, and then-196°C (liquid nitrogen) no further freezing events or water losses were detected. The cellular water loss and redistribution that occurs at-4°C is essential for post-thaw survival. Intercellular and inter-tissue diffusion distances are likely to influence the critical process of cryodehydration, hence the relationship between bud volume and post-thaw survival was considered. The observation that in some larger buds, the primary meristem did not survive cryopreservation and recovery was attributable to a secondary bud outgrowth, adding support for this line of enquiry. Bud volumes were measured for three apple cultivars, exhibiting high, medium and low survival following cryopreservation. The highest survival of primary bud meristems was associated with smaller bud volumes and for larger buds, secondary growth was responsible for almost two thirds of the recorded survival. The proportion of unfrozen, grafted control material that displayed secondary bud outgrowth did not exceed a quarter.
Analysis of freezable water content by DSC for apple dormant bud cryopreservation
Horticultural Science
Dormant bud cryopreservation is a valuable tool for the germplasm of temperate trees preservation. Freezable water content, as an important cryopreservation characteristic, was analysed by DSC. Scions of modern apple tree varieties (Malus domestica) were collected during the winter season from orchards, freeze-dehydrated to 26–32% of water content at –5°C and cryopreserved by the two-step procedure. Samples were rehydrated in moist peat after 4 months of cryopreservation and grafted on rootstocks in a field. Regeneration by sprouting buds on rootstocks was evaluated. The varieties were divided into three groups according to their water content and percentage of crystallized water. The regeneration in the three groups decreased with decreasing bud water content. Regeneration was higher than 80% in most of the varieties and reached 100% in almost 1/3 of the tested varieties. In only one variety, was regeneration lower than 40%, which is still a high regeneration rate for considering a...
Cold acclimation improves regrowth of cryopreserved apple shoot tips
Cryo letters
Cryopreservation is important for safeguarding the genetic resources of apple germplasm in Kazakhstan, the center of origin for apples. In this study, conducted with five apple genotypes [Malus domestica Borkh. and Malus sieversii (Ledeb.) M. Roem] we determined cold hardiness and the effect of cold acclimation on shoot tip recovery following cryopreservation using two techniques. Apple shoot tips were cold acclimated (CA) for 0 to 6 weeks and cryopreserved using PVS2 vitrification and encapsulation dehydration (ED). Cold hardiness was indicated by the temperature at which 50 percent of the shoot tips were lethally injured (LT50). For non-acclimated shoots, LT50 ranged from -6.7 degree C to -9.3 degree C. These LT50 values resembled the natural cold hardiness of field grown plants and resulted in 10-12 percent regrowth after cryopreservation. Acclimated plantlets had LT50 values of -12 degree C to -15 degree C after 1 to 3 weeks CA, and after 3 weeks CA, cryopreservation resulted in...
Cryopreservation of Dormant Buds from Temperate Fruit Crops to Optimize Working Collection Resources
2009
The water content of dormant Malus buds is comparable throughout the stages of the cryopreservation protocol, regardless of whether they come from cultivars that survive cryopreservation well or poorly. However, thermal analysis of dehydrated and frozen/thawed buds suggests that the distribution of water within them is different, with those from cultivars that recover poorly from cryopreservation retaining a greater bulk volume of freezable water (estimated by simple thermal analysis [STA]) than tolerant cultivars. Implications for the design of successful cryopreservation protocols for dormant buds are discussed.
Cryopreservation of Dormant Buds from Temperate Fruit Crops to Optimise Working Collection Resources
Acta Horticulturae, 2011
The water content of dormant Malus buds is comparable throughout the stages of the cryopreservation protocol, regardless of whether they come from cultivars that survive cryopreservation well or poorly. However, thermal analysis of dehydrated and frozen/thawed buds suggests that the distribution of water within them is different, with those from cultivars that recover poorly from cryopreservation retaining a greater bulk volume of freezable water (estimated by simple thermal analysis [STA]) than tolerant cultivars. Implications for the design of successful cryopreservation protocols for dormant buds are discussed.
Freezing temperature treatment induces bud dormancy in ‘Granny Smith’ apple shoots
Scientia Horticulturae, 2005
One-year-old, 'Granny Smith' apple (Malus  domestica Borkh.) shoots were selected randomly from commercial orchards in 1999 and 2003, cold stored at temperatures between 1 and 13 8C for varied periods, following a 12/12 h freezing temperature pre-treatment of À1/13 8C (supposedly nonchilling temperatures) for 1 or 2 weeks. The rate of budburst, determined after forcing at 25 8C, was used to follow the progression of bud dormancy. The freezing pre-treatment clearly enhanced (deepened) bud dormancy in all experiments. Clearly definable influences due to the presence of leaves during the pre-treatment were not observed on shoots cold stored at chilling temperatures. Trees were defoliated before leaf drop in late summer/autumn under field conditions by hand and using a spray containing 3% urea and 1.8% zinc sulphate in 2003. In 2001 the first two hand defoliation dates significantly enhanced dormancy, while in 2003 chemical defoliation had no effect. These data indicate that the leaves are not clearly involved in the perception of factors that are responsible for dormancy induction. As with dormancy release it is possible that the perception of induction factors, i.e. low temperatures, and as shown in these data, freezing temperatures, occurs within the buds themselves. #