Ex-situ Conservation of Plant Genetic Resources in Jordan

Globally, plant genetic resources are conserved to achieve the general objective of conserving plant genetic resources from degradation and depletion and providing the primary genetic material for plant breeders to produce improved varieties

Ex-situ Conservation of Plant Genetic Resources

Biodiversity in Jordan:

Jordan has a variation in Topography and geomorphology through the existence of four geographically vital regions:

1- Mediterranean Region: Forests constitute the bulk of vegetation.

2- Irano-Turanian Plateau: The vegetation consists of pastoral shrubs and grass plants.

3- The Arabian Desert represented by the oases (Azraq and Shumari).

4- Sudano-turanian: The vegetation consists of annual herb species.

It also varies climatically in terms of rainfall and temperature. For example, Ajloun recorded the highest rainfall (550 mm) and the lowest mean temperature (20 c), while Wadi-Araba recorded the lowest amount of rainfall (50 mm) and the highest mean temperature (30 c).

This topographic and climatic diversity in the Kingdom has created a diverse and unique ecosystem, not only among plant species, but also within these plant species. The number of plant species in the world is estimated at about 250,000 species, of which 2500 in Jordan. (Eisawi et al., 1996).

This means that 1% of the species in the world. taking into consideration the small size of Jordan, which does not exceed 90 thousand square kilometers. These local plant species are not only highly heterogeneous plants, but also are rich genetic material with multiple unique genes that enable them to survive even in the most difficult environmental conditions such as water shortage, low fertility, soil problems as well as non-environmental factors such as pests and Diseases.

Threats to Biodiversity and Genetic Resources:

Plant biodiversity, with genetic resources, is exposed to multiple environmental and non-environmental threats such as:

1- Overgrazing and the absence of a traditional grazing cycle:

• Mountainous areas: degradation of vegetation
• Areas of steppe: degradation of vegetation, desertification, soil erosion
• Badia areas: degradation of vegetation due to the settling of the breeders in the Badia region.

2- Wood cutting.

3- Urbanization.

4- Natural disasters.

5- Pests and diseases.

6- Pollution.

7- Loss of natural vegetation and replacement of exotic species.

Genetic Resources Conservation Mechanism:

- Definitions:

• Biodiversity: is the total natural diversity within and between organisms and their adaptation to environmental conditions (Bioversity International).
• Genetic resources are plant genetic material including modern varieties, primitive varieties, local varieties and wild relatives of crop plants that are important to present and future human generations.
• Genetic Material: A variety of different genotypes that can be conserved and used.
• Gene bank: a place to store genetic resources in the form of seeds, pollen or tissue cultures, and in the case of the field genebank, plantation of germplasm in the field.
• Accession: Plant, seed sample, breeding line found in a genebank or breeding program for conservation and use.
• Wild relatives: uncultivated relatives of plant species.
• Landraces: crop varieties developed by farmers and adapted to local environmental conditions.
• Genetic diversion: loss of genetic diversity within a particular species or a population over time, or genetic deficiency of a particular species due to human intervention, environmental changes, etc.

Globally, plant genetic resources are conserved to achieve the general objective of conserving plant genetic resources from degradation and depletion and providing the primary genetic material for plant breeders to produce improved varieties through the following tasks:

• Plant genetic resources collection
• Characterization and evaluation of plant genetic resources
• Documentation and conservation of plant genetic resources, using two main mechanisms:

     1- Ex-situ conservation:

• Conservation in Genebanks:

Storage at very low temperatures (-20 ° C) and low humidity (18 c) to preserve the genetic material for more than 100 years. Genetic material can also be stored in the form of plant tissues (Callus) and stored in liquid nitrogen at a temperature of -196 c. This method is usually followed to store the genetic material of plants that are difficult to propagate by conventional methods.

• Conservation in field banks:

This is done by establishing special fields for plant species outside their original location in order to preserve and monitor them and conduct field research and studies in the field. This method is usually followed in the conservation of tree genetic resources.

    2- In-situ conservation:

The genetic material is conserved as plant population in its original form and in the same location in nature. These plant communities are monitored and maintained by establishing a number of preventive measures and special laws that guarantee the protection of plant species. The nature reserves are one example of conservation mechanism In-situ.

The importance of the Gene-bank as a method of conservation of genetic material:

1. The possibility of storage for long periods.

2. Provide a documented database.

3. Provide genetic material for people of interest.

4. Represents solutions to rehabilitate areas of degradation.

Limitations of Genebanks:

1- The need for specialized skills.

2- Loss of natural evolution of components of the genetic material.

3- Limited quantity of material saved.

4- The need for financial resources.

Role of Plant Breeders in the Conservation of Genetic Resources:

1. Contribute to the development and improvement of preserved genetic material.

2. Provide the documentation system with accurate evaluation and characterization of accessions.

3. Providing the Genebank with accessions with important characteristics.

 The role of farmers in the conservation of plant genetic resources:

1- Selection of genetic material for specific environments.

2- Selection of genetic material according to market requirements.

3- Integration into specialized breeding programs.