DNA banking: A complementary approach for safe conservation of genetic resources
Authors: Dhammaprakash P. Wankhede, J. Aravind, Sheel Yadav, Bharat H. Gawade
ICAR-National Bureau of Plant Genetic Resources, Pusa campus, New Delhi
Modern agriculture has brought uniform and high yielding varieties to farmer’s field replacing the diverse, traditional varieties and their wild relatives. Green revolution, which involved extensive cultivation of high yielding varieties over large parts of arable land in developing countries, also had remarkable adverse impact on crop diversity at farmer’s field. The role of gene banks in preserving genetic diversity by conservation of diverse plant genetic resources had never been so crucial than the recent times. Considering the seriousness of the issue, several agricultural research institutes at national and international level have initiated ex- situ conservation of plant germplasm. The curators of gene banks through persistent efforts, have collected and conserved a decent portion of crop genetic diversity. Proper utilization of the conserved germplasm by plant breeders or farmers requires a detailed evaluation and characterization of the available germplasm. Therefore, effective characterization and evaluation of germplasm has become an integral part of strategic germplasm conservation and utilization. To accelerate characterization, evaluation and utilization of plant genetic resources, ‘DNA bank’ could provide an efficient option since the molecular characterization of germplasm could become order of the day sooner or later (Ebert et al. 2006).
DNA banks are meant for conservation of genomic DNA and/ or tissue samples for the purpose of DNA extraction. The purpose of the DNA bank is to accelerate downstream research using advanced techniques of molecular biology and facilitate strategic conservation, characterization and enhance utilization of germplasm. It is obvious that the material in DNA bank would not help re-create the lost species but it can serve as a complementary approach for conservation of genomic resources, along with other existing conservation approaches. However, these DNA samples per se could be of great value if there is a catastrophic loss of species which are under threat of extinction. There are several species which are under the danger of extinction, in spite of several efforts of in-situ or ex-situ conservation. DNA banking of such species would at least make sure the availability of its genome with us for future use (Ebert et al. 2006). With the tools of molecular biology, such genomes could be further maintained for future, thus ensuring access to the blueprint of the species for a long time to come even after its extinction.
With the advent of high throughput technologies, establishment of DNA banks will open new opportunities which will help in better management and utilization of germplasm. DNA based markers offer high throughput complementary information in addition to the phenotypic data and classical morphological descriptors (de Vicente et al. 2004). Availability of such genotypic and phenotypic information for gene bank accessions improves not only effective and strategic management of gene bank but also utilization aspects (Karp et al. 1997). It helps identification of gaps in germplasm collection and this helps in planning new exploration and collection tours. Such geno-phenotypic information also gives an idea of genetic diversity within/between gene pools and helps in identification of unique and duplicate germplasm in the gene banks (Karp et al. 1997). It may further help in monitoring and studying genetic stability and integrity of gene bank accessions and monitoring contamination caused by regeneration especially in cross/often cross pollinated crops.
The large numbers of accessions with poor characterization often makes it difficult for plant breeders to access and efficiently utilize germplasm collection. Application of molecular markers to study existent genetic diversity in large collections to establish core collections could greatly enhance utilization of germplasm resources available in gene banks (Hodgkin et al. 1995). DNA banks could accelerate application of molecular markers in plant genetic resources and therefore play a crucial role in germplasm characterization, thereby facilitating efficient gene bank management and germplasm utilization (Ebert et al. 2006).
Application of molecular markers to study marker-trait association studies is also expected to be accelerated with the establishment of DNA banks. DNA markers/sequence information of diverse plants species and accessions may further serve as additional valuable information for evolutionary studies.
Thus, DNA banking although a complementary approach of conservation, is expected to offer a great help not only in effective management of germplasm and its conservation but also in utilization of germplasm, in times to come.
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About Author / Additional Info:
Scientist, Division of Genomic Resources, ICAR-National Bureau of Plant Genetics Resources, New Delhi , India