**9.2 Ex-situ conservation**

Another methodology involving the collection of plant gardens and banks of seeds where the plants are grown under natural conditions [41]. Seed banks are maintained and produced by research institutions and universities produced via the technique of tissue culture and utilization of much lower temperature in the environment for its operation [42]. It also ensures that the plant materials are easily available, characterization is done efficiently and well documented and its exposure to the outer environment is safe i.e., it should not possess any threat to the natural ecosystem of humans as well as animals. However, it provides the best alternative to naturally existing methods which in addition to providing an opportunity to wild species having desirable traits to continue undergoing the evolutionary process in a naturally existing environment. This method has the advantage of safeguarding the germplasm while it is in its natural environment resulting in the genetic variation in naturally occurring verities and is readily available for use. Examples of plant undergoing this subtype of preservation under biotechnological area are sugarcane, cocoa, and maize, etc. [43].

This is also referred to as offsite conservation which employs the conservation of species outside their natural habitat or system. In this method, the genetic information of the plant is preserved in form of banks which may be either seed or gene bank or in the form of cultures to increase their half-life so that they can be used for a long period inefficiently [44]. The class of preservation technique results in the formation of collection or bank of genes, DNA, seeds, and germplasm forming a genetic library in the form of gardens. This will lead to the creation of a good option for the conservation of species that are thought to be endangered or near the extent of it, which are primitive and in turn, are much valuable for use in industry for commercial purposes. It includes certain techniques such as cryopreservation and other genetic transfer approaches for the eradication of diseases, pest and stress control, and lastly conservation of endangered species in the long run [45]. It is almost similar to that of in-vitro methodological practice. Other disadvantages include loss of viability of seed structure, destruction of the crop by pest or insect, poor germination of a seed plant, and lastly, it is a much expensive procedure [46]. On the other hand, major advantages can be summarized as,


The most advanced form of preservation of genetic resources is to maintain them in laboratory conditions. This is the conservation technique which employs the use of test tubes or laboratory apparatus which is sealed in one or other way for maintenance of resources [48]. The genetic resources such as tissue cells or callus are placed in the sealed tubes which operate on the fact that plant parts can be kept alive under controlled laboratory conditions which proves the fact that plants are totipotent. This means that every part of a plant can develops into a whole organism. This phenomenon has made this fact clear that disease-free plants and species can be transferred to the next generation within the laboratory controlled conditions [49]. Or in other words, engineered species provide a viable means for the transfer of pest and insect-free species from one generation to another. The source of such genotypes is from the culture of laboratories or having origins from international seed banks [50].

In vitro conservation of plants was first done in the mid-1970s. Although whole 'is not can be regenerated from any part of the plant because of its totipotency but due to the involvement of unorganized culture there exist some risks of a generation of somatic mutation and mutants. In comparison to it, the cultures containing somatic meristem culture are much more stable in their transformation mode but also it can propagate more frequently as these areas do not have to recover after differentiation [49]. Most efficient storing systems are usually not much expensive, are easy to maintain, and reduce the work labor and load in germplasm working bank. Scheduled monitoring of the cells along with viability and contamination assessment is not that necessary. The exploitation of in Vito technique of genetic conservation is hindered if any species is unable to prorogate to the next generation from tissue or cell culture [51]. For example, a proper technique for the prorogation of coconut does not exist yet unlike other crops of this class which can be propagated inefficient way via callus differentiation. But in this case, the leaves or plantlets can only be produced from a zygote or embryo. Each embryo in this case will produce a new plant which represents no further division of genetic material. In the same manner, the effect of in-vitro culturing is much less for woody plants as compared to other species as it can result in difficulty in culturing and regeneration of new species [52]. In these cases, less research has been done for the development of an appropriate cultural technique in vitro. But a thorough examination of the problem occurring in the handicap pathway of procedure for wood culture can solve this problem, presenting a suitable solution to the development of plant and conservation of their genetic resources efficiently [53].

The most important drawback of this phenomenon is that it requires the utilization of modern technology and labor force under the controlled conditions of an aseptic environment. Also, it requires proper laboratory skills with excessive usage of electricity which makes this procedure much labor-intensive and expensive [54]. This process is helpful in the production of disease-free varities of plants that are also pest-free and these species include sugarcane etc. The produced genetic resources are used in several ways such as genetic improvement, maintenance of biodiversity, mechanism-based research of ecosystems, classification according to taxonomy, monitoring of environmental characteristics, epidemiological, and forensic based studies. One of the main strategic reasons behind germplasm conservation is that it maintains biological diversity and provides germplasm which is validated in both genotypic and phenotypic aspects [55]. Germplasm is either conserved in the form of seed or meristem form.

#### **10. Gene bank**

Gene banks are the type of repository in biology for the preservation of genetic resources. In the case of plants, it is done by storing in laboratory conditions,

#### *Germplasm Conservation DOI: http://dx.doi.org/10.5772/intechopen.96184*

freezing cuts from the plant materials, or maintaining stocks of seed. Accession is the term provided to each sample in a gene bank like the species or variety. In plants, it is easy to unfreeze the materials for their propagation and usage.

Gene banks are also classified as both in vivo that is within the body and in-vitro which involve sustaining of characters in proper laboratory conditions. The type of gene bank where traits or alleles are stored by employing conventional methodologies are termed in-vivo. For example in the form of seeds and vegetative collections [56]. While the subtypes where the characteristic resources are stored in form of non-conventional methods in form of cellular structure and tissues are referred to as in vitro. Both techniques are of prime importance in the development of valuable trait crops for breeders to develop both new and improved varieties [57]. This involves using DNA as a source of DNA in terms of germplasm being employed in breeding technologies. When these are properly identified and after that efficiently characterized, it will result in the production of the transgenic organism which can express these genes. Genetic disruption can be avoided by the phenomenon of transformation which also involves sexual hybridization. It is not limited by compatibility from the sexual life cycle and can be evolved from other forms of life in the short run. The transgenic genes are helpful in the production of plants which in addition to herbicide-resistant are also pest resistant and are conveniently preserved as a transgenic or cloned form of genetic material. The process is limited by the identification of potable genes which will result in the production of higher yield along with greater stability of Transformants in host genera. Such genes have been produced successfully for conservation as well as patent purposes so that they can be employed at a commercial level. Economically or technically, is not worthy in the future that this synthesis of the gene will store these genetic traits in the form of physical germplasm i.e., in form of seeds, tissue, or the whole plant, etc. Conservation of DNA molecules and similarly the assembly of these molecules in the form of DNA data sequence is not the best alternative to conventional methods for germplasm because genes are not coordinated in them in a small similar fashion.

Recently with the discovery of artificial chromosomes in yeast has raised the fact that coordinated assemblies of genes can be made and therefore can be conserved which will allow further morphological or phenotypical changes to be engineered in the laboratory efficiently. To use them practically, it is important to conserve the host organism but the genetic information in them is not yet fully discovered. But gene liberates, sequence data, and gene banks cannot be employed to reproduce a whole organism but have a significant role in preserving genetic resources of crop plants which are either on the extent of danger or found to be endangered. The conservation of plant or genetic diversity involves the collection of small parts of plants such as tissues, cells, shoots, etc. A tissue sample from all the plants and species will be collected in liquid nitrogen as described in cryopreservation at a much lower temperature of freezing point. In theory, these samples are not indefinite and DNA extraction is not performed until recommended. So, at that moment, DNA can be identified, immobilized in a membrane to act as a source of a specific gene or sequence of DNA molecules. The technique is helpful in the conservation of both undefined and undescribed species of plants whose seeds cannot be stored directly and is used for diverting those whose seed values have been found earlier and observed in germplasm banks already. DNA sequencing is carried out in almost all laboratories throughout the world because they can be compared to novel sequences with those which are properly and characterized considerably. Comparisons also highlight the unrevealed homologies and suspected functional properties between the organisms which are unrelated. Most organizations support coordinated DNA sequencing and storage. The most famous banks are the European molecular biology laboratory located in the US, GenBank operated by the United States laboratory. The rapidly increasing data of sequence raises voice on important problems of storing and facilitating rapid comparison regarding new information on data sequence of the gene. Gene banks are of three types which include;
