This paper presents a review of fundamental aspects of plant cryopreservation. Liquid nitrogen has several advantages over storage of vegetatively propagated material under normal low-temperature in vitro culture and could also help in preserving genetic biodiversity. Development of efficient cryopreservation protocols based on the induction of tolerance to freezing and/or desiccation is also discussed. Cold and/or preculture acclimatization leads to ultrastructural, physiological and molecular changes in cells and they are important for improving viability after cryopreservation. The application of vitrification-based procedures and ultra-fast freezing/thawing rates could be effective and reliable for wide variety of plant species/ tissues and relatively genotype independent. Majority of papers demonstrate that the liquid nitrogen allows high viability rates and re-growth without a loss of biosynthetic capacity. Up to now, there has been no clear evidence of morphological, cytological or genetic alterations due to cryopreservation.
Cryopreservation is important for the long-term conservation of plant genetic resources, especially for the species producing recalcitrant seeds and clonally propagated crops which are proliferated through grafting or as vegetative cuttings, suckers, roots, tubers and bulbs. Despite the fact that in liquid nitrogen temperature the cell division and metabolism are arrested, the factors associated with cryotreatment, cryostorage or plant recovery could be a source of somaclonal variations. The lecture assesses an attempt of attained knowledge within the influence of cryopreservation on the genetic integrity of regenerated plants or recovered tissue. Assessment of genetic and epigenetic stability of the recovered plants derived from cryopreserved plant material is an important step to success of any storage protocol. Until now, from among 64 published papers, only 7 have shown genetic changes in plantlets regenerated after cryopreservation, and 3 - variability in tissue recovered after cryostorage without consequences in regenerants. Epigenetic changes were described using isoschisomers and MSAP, AMP or RAPD methods in 9 works. It was suggested that the processes of cryoprotection and cryostorage had an impact on DNA methylation status, it could lead to alterations in chromatin structure and changes in gene expression. However, majority of the works reported on the insignificant or any influence of cryopreservation on the plant material.
The aim of the presented review is to analyse the possibilities of creating highly morphogenic Triticum aestivum genome using generative hybridisation of various wheat forms and its relatives.
Cryopreservation is recognised as the most efficient method of plant genome preservation and embryogenic potential of plant in vitro cultures with non-changed status. Because of the risk of biological degradation of tissue during freezing treatment and it various sensibility on the chilling stress, the individual treatment with cryoprotectance and parameters of the temperature decreasing is highly required. In this presentation, following subjects will be discussed: 1) description of suspension cultures of various gentians, 2) cell pretreatments for surviving the stress of low temperature, 3) rearrangement of cell cytoplasm because of high sucrose concentrations, 4) the role of sucrose in the development of freezing tolerance and surviving of gentaiana suspensions, 5) the effect of strong plasmolysis induced by 3 M glucose.
Cryopreservation offers the possibility for long-term storage of genetic resources with maximal genotypic stability, using a minimum of space and maintenance. At present it is actively used all over the world for storage of plant material: seeds, pollen, spores, dormant buds or apical meristems in genebanks. The development of biotechnology led to the production of a new category of germplasm for cryostorage: in vitro obtain tissues, organs, embryos, special cell lines and genetically modified plant material. The maintenance of in vitro collections remains risky regarding losing accessions due to the contamination, human error or somaclonal variation. The classical slow cooling was the first standard protocol developed for hydrated plant tissues. This method is mainly used for cryopreservation of non-organized tissues, for example: cell suspensions and calli, or apices of cold-tolerant species. For differentiated structures, new cryopreservation techniques such as vitrification and encapsulation/dehydration procedures or droplet method are efficient and reliable. These freezing techniques have been successfully, routinely applied for cryopresevation of various plant material of temperate and tropical climate species. So far, cryopreservation procedures are developed for in vitro tissues and recalcitrant seeds of about 100 and 40 species, respectively.
JavaScript is turned off in your web browser. Turn it on to take full advantage of this site, then refresh the page.