What is Germplasm conservation?Germplasm is the broad term, which refers to the hereditary genetic material or plant genotype representing whole genetic material transmitted to the offspring by germ cells. Germplasm conservation has significance for breeding, as it provides the raw material for the breeder to develop various crops. Hence, the Primary objective of Germplasm conservation is to preserve the genetic material of a specific plant or genetic stock for its use in the future. Due to the use of modern agricultural varieties and hybrids, primitive crops are on the path of extinction. To protect the plant’s genetic material, seeds, vegetative propagules are used as conventional methods to preserve genetic material for primitive plant species. Plant seeds and propagules are collected in in-vivo gene banks. Plant parts or tissue through tissue culture is collected and conserved in the in-vitro gene bank.
Germplasm conservationInternational Board of Plant Genetic Resources (IBPGR) is the global body established for germplasm conservation. The main objective of the body is to provide support for the collection, conservation and utilization of plant genetic resources globally. There are two main approaches for germplasm conservation
- In-situ conservation: In this conservation of germplasm is done in their natural environment such as national parks, gene sanctuaries, etc. It provides the natural habitat for the preservation of land plants with genetic diversity.
- a) Environmental hazards may lead to loss of germplasm
- b) The maintenance and cost is very high
- Ex-situ conservation: in this method seeds, or in-vitro cultures of plant cells, tissues, or organs can be used to preserve genetic material as gene banks for long-term storage. This is the most convenient method compare to in-situ conservation.
- Seeds are the most common and conventional material to conserve plant germplasm.
- The majority of plants are propagated through seeds.
- Seeds occupy a small place and are convenient for transport to various places.
- Seed viability is reduced over some time
- Seeds are prone to pathogenic infection and may lead to their destruction
- Vegetatively propagated plants have no use for this seed conservation e.g. for potato, Ipomoea etc
- Clones cannot be maintained by seed conservation.
In-vitro methods for germplasm conservationThree approaches are used for in-vitro germplasm conservation namely
- Cryopreservation (freeze-drying)
- Cold storage
- Low pressure and low Oxygen Storage
- Cryopreservation (freeze-drying): In this method, the storage of plant tissues and cells is done in a frozen state. Plant cells or tissues are preserved for the long term at a very low temperature. The principle of cryopreservation is the use of Cryoprotectants to reduce temperature to bring plant cells and tissue culture to a non-dividing state or zero metabolism. Cryoprotectants such as glycerol, mannitol, dimethylsulfoxide (DMSO), and proline are used to store plant tissues at low temperatures. These Cryoprotectants prevent damage caused to cells by freezing or thawing.
- Over solid carbon dioxide (at -790 C)
- Low-temperature deep freezers (at -800 C)
- In vapor phase nitrogen (at -1500 C)
- In liquid nitrogen (at- 1960 C)
- Cold storage: in this method germplasm is conserved at low and 1-90 C non-freezing temperatures. This technique allows us to slow down the growth of plant material, in contrast, to completely stop cryopreservation. Hence the method is also known as slow germplasm conservation. Cryogenic injuries are avoided by this method. This method is simple, cost-effective and the yield and survival rate of germplasm is good.
- Low-pressure storage (LPS) and low oxygen storage (LOS): in LPS the atmospheric pressure around the plant material is reduced, which partially decreases the pressure exerted by the gases around the germplasm. This lowered partial pressure declines the growth of plants in-vitro. This LPS system is used for short-term and long-term storage of plant material. In LOS the atmospheric pressure i.e. 260 mm Hg is maintained by the addition of inert gases especially nitrogen while the oxygen concentration is reduced. The partial pressure of Oxygen below 50 mm Hg declines plant tissue growth. This is due to the reduced availability of O2, which decreases CO2 This phenomenon results in reduced photosynthetic activity and thereby inhibiting plant tissue growth and dimension. Long term conservation of plant material by LOS inhibits plant growth after certain dimensions.
Applications of Germplasm storage
- Plant materials like cells and tissue cultures of several species can be cryopreserved and maintained for a long time
- Cell cultures used for the production of secondary metabolites can be conserved for a long time by cryopreservation
- Plant material free from pathogens can be stored and can be propagated whenever needed.
- Somaclonal variations in culture can be conserved by this cryopreservation.
- Conservation of plant material from endangered species can be done
- Germplasm developed from genetic manipulations can be conserved.
- Globally information can be exchanged by the establishment of germplasm banks.
- It requires expensive instruments for conservation
- Trained personnel is required for these techniques.
Multiple-choice Questions1. __________is the advantage for the seed as germplasm conservation EXCEPT: a) Plants are propagated through seeds b) Seed viability is enhanced over a time c) Conventional material to conserve plant germplasm d) Seeds occupy a small place 2. Which of the following method is used for in-vitro germplasm conservation a) Cryopreservation (freeze-drying) b) Cold storage c) Low pressure & low Oxygen Storage d) All 3. Which of the following is the appropriate method for cryopreservation a) Over solid carbon dioxide (at -790 C) b) Low-temperature deep freezers (at -800 C) c) In vapor phase nitrogen (at -1500 C) d) In liquid nitrogen (at- 1960 C) 4. The following are the Cryoprotectants EXCEPT: a) Glycerol b) Mannitol c) DMSO d) Methanol 5. Cryoprotectants are used in cryopreservation to________________ a) Prevent damage caused to cells by freezing b) To preserve cells from pathogens c) To preserve cells from freezing d) To preserve cells from aggregation 6. The principle behind this cryopreservation is to bring plant cells and tissue cultures to Maximum metabolism and or rapid cell division state by reducing temperatures in the presence of Cryoprotectants. a) True b) False 7. Temperature required for cold storage for germplasm conservation is_____________ a) 1-90 C b) 9-150 C c) 15-200 C d) 20-300 C 8. Which of the following system is used for short term and long term storage of plant material a) Cryopreservation b) Cold storage c) Both d) Only B 9. Germ storage is ______ a) Used to preserve cells or tissues b) Used for easy transport c) Used to prevent plant material from pathogens d) a and c 10. Cryogenic injuries are avoided by __________ a) Cryopreservation (freeze-drying) b) Cold storage c) Low pressure and low Oxygen Storage d) All For More Standard and Quality Question Bank you can Join Our Test Series Programme for GPAT, NIPER JEE, Pharmacist Recruitment Exam, Drug Inspector Recruitment Exams, PhD Entrance Exam for Pharmacy Participate in Online FREE GPAT TEST: CLICK HERE Participate in Online FREE Pharmacist TEST: CLICK HERE Participate in Online FREE Drug Inspector TEST: CLICK HERE Participate in CSIR NET JRF Mock Test Participate GATE Mock Test Answer Key
- U. Satyanarayana, biotechnology, 1st e.d. Kolkata, books & allied (p) ltd publishers, 2005 page: 565-571