•Seven Ribes species, other than black and red currant, might be cryopreserved by dormant winter buds.•Pretreatments with cryoprotectants and an antioxidant increased post cryopreservation viability ...for most accessions.•Post LN-storage viability was dependent on interaction of genotype, processing year and pretreatment.
Currant and gooseberry plants (Ribes L.) are native to the temperate regions of the Northern hemisphere through high elevations in Mexico and Central America to the mountainous regions of South America. Annually, the global production is about 838 MT. The fruits are used for cassis, juice preserves, in bakery, dairy products and pharmaceuticals. Some species such as black currant (Ribes nigrum) have antimicrobial, antitumor and immunostimulatory qualities; hence, interest is growing in crop improvement using a diversity of plant genetic resources. Active germplasm collections preserve Ribes cultivars as clonal plantations in the field or under protected cultivation, and species as plants in the field or seeds in cold storage. Long-term preservation of Ribes germplasm may be accomplished by various methods, one of them is cryopreservation of dormant winter buds (DB). This method is reported for preservation of R. nigrum. We have investigated the possibility of applying DBs for cryopreservation of other Ribes species. Eleven accessions in seven species (R. aureum var. aureum, R. aureum var. villosum, R. cereum, R. erythrocarpum, R. mascalerium, R. turbinatum and R. uva-crispa) were cryopreserved over two winter seasons without a pretreatment (standard), with a cryoprotectant (0.75 M sucrose) or a cryoprotectant with an antioxidant (0.75 M sucrose with 0.75 mM vitamin C). A 2-year average viability varied significantly among the accessions processed with the standard method (10 to 87.5%) and among accessions processed with the pretreatments (32.5 to 97.5%); however, the difference between the standard and treatment procedures was not significant. A significant difference in viability between the processing years was observed and there was an interaction between accession, year and treatments for seven accessions processed in three treatments but not in the four accessions processed in the two treatments. Cryopreservation of the broad species in the Ribes germplasm collection may be supported by identifying modifications of the standard cryopreservation procedure.
Potatoes are consumed by millions of people and are the survival food in several countries. Cultivated varieties of potato (Solanum tubersosum L.) are results of selection and crossing of many wild ...species. Only 8–13% of wild potato species used for food are preserved by either in situ or ex situ methods. The U.S. National Potato Germplasm Collection maintains over 5900 accessions, of which 75% are crop wild relatives (CWR). The objective of the study was to investigate regrowth of cryogenically stored clonal propagules (shoot tips) of selected CWR accessions maintained in the collection. Sixty-nine accessions from 30 Solanum species and six accessions that are not yet assigned to a species were cryopreserved by a droplet vitrification method at the NLGRP. The post cryopreservation regrowth varied from 40 to 100% (average 68%) but was not significantly different between the tested accessions. Regrowth of six accessions tested after 10 years of cryogenic storage was between 35 and 90% (average 66%) and was significantly different from their initial regrowth (average 87%); the largest viability loss was in S. condolleanum; but for the other five accessions the regrowth was between 45 and 90% (average 72%) and suggested at least 10 years of successful storage in LN was possible. Twelve potato wild species cryopreserved in this study were reported in literature as important for developing cultivated varieties for changed weather conditions.
Cryopreservation of temperate woody-plant material by dormant buds is less expensive than using shoot tips isolated from tissue cultured plants; however currently, dormant buds are used only for ...preservation of selected temperate tree and shrub species. Using dormant buds could be an efficient strategy for long-term preservation of blueberry (Vaccinium L.) genetic resources. In this study, viability of V. hybrid ‘Northsky’ (PI 554943) dormant buds was evaluated at 30 harvest dates over three consecutive fall/winter seasons to determine the optimal harvest time that promotes high post cryopreservation viability. Twigs with dormant buds were cut into 70 mm segments containing at least two nodes, desiccated, slowly cooled, stored in liquid nitrogen vapor and tested for post-cryopreservation regrowth. The highest regrowth of cryopreserved dormant buds was observed for buds harvested in mid-December and during the first half of January. Pearson's correlation coefficients were computed to evaluate the association between bud characteristics and viability at harvest date and logistic regression models were fit to test the ability of twig characteristics and temperatures to predict post cryopreservation bud viability. Post-cryopreservation viability was negatively correlated (p < 0.05) with average minimum, maximum and daily mean temperature preceding the bud harvest but was not correlated with the dormant bud initial and end moisture content, twig diameter, the number of dormant buds/cm of twig length and the number of days in desiccation. Regression tree analysis suggested post-cryopreservation viability to be between 52 and 80% for dormant buds harvested after a 10 day average maximum air temperature of <11.2 °C. Pre-harvest air temperature was a significant indicator of optimal dormant bud harvest time to produce adequate viability for long term preservation of blueberry genetic resources.
Willow (Salix L.) species have good qualities for becoming a biomass crop for production of biofuels. They grow on marginal soils, produce high yields of wood in a short period of time, and are ...easily propagated. Salix is one of the few genera that may be cryopreserved as dormant winter buds (DBs) instead of using tissue culture techniques. The objective of our study was to evaluate selected factors that affect cryotolerance of nine Salix germplasm accessions in the USDA‐ARS National Plant Germplasm System collection. One‐year‐old branches harvested in January over 3 yr were cut into either 6‐ to 7‐ or 10‐cm segments containing at least two DBs. Segments were treated with a slow‐cooling procedure and stored in vapor‐phase liquid N (LNV). Control segments were stored at −5 °C until planting. The LNV‐exposed and the −5 °C‐stored nodal segments were warmed and directly planted in a cold greenhouse. Six weeks later, the material was evaluated for shoot and root development. Segments that developed a shoot were considered viable. Average viability varied among years (0–35.1%) even for the same accession, species (4.2–51.4%), and segment length. Dormant buds on 10‐cm segments had higher average viability (82.2%) than did DBs on 6‐ to 7‐cm segments (43.9%), suggesting higher suitability for cryopreservation. In the material studied, Salix DB viability was correlated with branch diameter, DB density, and the ability to develop shoots and roots prior to cryopreservation.
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