conservation of plant genetic resources.
shiva charan
2nd_lecture.pdf
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S. Mohan Jain Department of Agric. Sciences, University of Helsinki, PL-27, Helsinki Finland
Genetic erosion and conservation of genetic diversity
Genetic erosion is the loss of genetic diversity—often magnified or accelerated by human activities.
In native plant populations, genetic erosion results from habitat loss and fragmentation
Also result from a narrow genetic base in the original collections or by practices that reduce genetic diversity
What is Genetic Erosion
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The major driving forces behind genetic erosion in crops are: variety replacement, land clearing, overexploitation of species, population pressure, environmental degradation, overgrazing, policy and changing agricultural systems.
The main factor, however, is the replacement of local varieties of domestic plants and animals by high yielding or exotic varieties or species.
A large number of varieties can also often be dramatically reduced when commercial varieties (including GMOs) are introduced into traditional farming systems.
Many researchers believe that the main problem related to agro-ecosystem management is the general tendency towards genetic and ecological uniformity imposed by the development of modern agriculture.
Conventional hybridization for higher yield, genetic engineering and the resulting loss of biodiversity, a threat to food security
Genetic erosion
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Lost genetic diversity
The widespread use of genetically uniform modern crop varieties has caused agricultural crops to lose about 75% of their genetic diversity in the last century.
Today, just 30 crops account for 90% of calories consumed by people, while 14 animal species account for 90% of all livestock production
This lost genetic diversity reduces the potential for modern crops to adapt to, or be bred for, changing conditions – and so directly threatens long-term food security.
The replacement of traditional and local crops and farm animals with more genetically uniform, modern varieties has caused the genetic erosion of crops and livestock species around the world.
Agriculture and animal husbandry, green revolution popularized the use of conventional hybridization to increase yield many folds by creating "high-yielding varieties".
Often the handful of breeds of plants and animals hybridized originated in developed countries and were further hybridized with local verities, in the rest of the developing world, to create high yield strains resistant to local climate and diseases.
Local governments and industry have been pushing hybridization aggressively that several of the wild and indigenous breeds evolved locally over thousands of years having high resistance to local extremes in climate and immunity to diseases etc. have already become extinct or are in grave danger of becoming so in the near future.
Due to complete disuse because of un-profitability and uncontrolled intentional, compounded with unintentional crosspollination and crossbreeding (genetic pollution) formerly huge gene pools of various wild and indigenous breeds have collapsed causing widespread genetic erosion and genetic pollution resulting in great loss in genetic diversity and biodiversity as a whole[
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A genetically modified organism (GMO) is an organism whose genetic material has been altered using the genetic engineering techniques generally known as recombinant DNA technology.
Genetically Modified (GM) crops today have become a common source for genetic pollution, not only of wild varieties but also of other domesticated varieties derived from relatively natural hybridization.
Genetic erosion coupled with genetic pollution is destroying that needed unique genetic base thereby creating an unforeseen hidden crisis which will result in a severe threat to our food security for the future when diverse genetic material will cease to exist to be able to further improve or hybridize weakening food crops and livestock against more resistant diseases and climatic changes.
Genetic pollution is a controversial term for uncontrolled gene flow into wild populations.
This gene flow is undesirable according to some environmentalists and conservationists
Genetic pollution is of late being associated with the gene flow from a genetically engineered (GE) organism to a non GE organism,frequently by those disapproving of such gene flow.
Genetic pollution
Uncontrolled spread of genetic information (frequently referring to transgenes) into the genomes of organisms in which such genes are not present in nature (FAO)
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Genetic diversity is lost in much the same manner as species become extinct.
Habitat loss and habitat fragmentation can reduce the size of plant populations
If the habitat and not just the plants are removed (such as in land conversion), and there is no subsequent regeneration from seed banks or previously collected seeds, then loss of genetic diversity can occur immediately
The link between habitat fragmentation and loss of genetic diversity has been well established, both theoretically and empirically, particularly in forest tree species.
But even if genetic diversity is not lost immediately, it is often reduced gradually in the resulting smaller populations.
The relationship between population size and loss of genetic diversity has been well established .
Generally, smaller populations tend to lose genetic variation by genetic drift much more quickly than larger populations.
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Habitat fragmentation is usually defined as a landscape-scale process involving both habitat loss and the breaking apart of habitat.
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Genetic erosion in Greece: Decline of folk varieties in wheat crop
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Plant diversity is the key in food security
FAO’s governing Council approved the Second Global Plan of Action for Plant Genetic Resources for Food and Agriculture, which represents a renewed international commitment to ensuring effective management of plant diversity as a key element in fighting poverty and achieving increased food security in the face of climate change (December 2011, Rome)
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Humans eat about 150 plant species, and 12 of those are the primary crops that make up most of the world’s food. The drastic decrease in crop diversity since 1900 is known
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Genetic diversity in maize, beans and Amaranthus
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Global warming can be defined as “the steady rise in the average temperature of the Earth’s atmosphere and oceans due to trapping of heat in the atmosphere by greenhouse gases.”
The major greenhouse gases- 1) water vapor, causes 36–70% of the greenhouse effect;
2). carbon dioxide (CO2), which causes 9–26%;
3). methane (CH4), which causes 4–9%;
4) ozone (O3), which causes 3–7%.
Global warming and Climate change
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1. The continuing increase in greenhouse gas emissions raises the temperature of the earth’s atmosphere
2. This results to melting of glaciers, unpredictable rainfall patterns, and extreme weather events
3. The accelerating pace of climate change, combined with global population and depletion of agricultural resources threatens food security globally
Effect of climate Change in Agriculture
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Source: thedailybeast.com
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Male fish becoming 'feminized' by pollutants in Spanish waters- Times of India
Endocrine disrupting chemicals (EDCs) acting as oestrogens — the primary female sex hormones — are seeping into the waters and causing reproductive and developmental disturbances,
Immature eggs were found in the testicles of a number of male fish- University of the Basque Country
The chemicals involved are found in everyday products such as pesticides, contraceptive pills and detergents.
They are thought to enter the estuaries after getting through the cleaning systems in water treatment plants or as a result of industrial and farming activities.
Marine Environmental Research journal
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Intergovernmental panel on climate change (IPCC) chairman Rajendra Pachauri (L)
Nobody on this planet is going to be untouched by the impacts of climate change
Energy - Reduction in energy demand for heating, but more energy required for cooling homes and commercial spaces - May influence integrity and reliability of pipelines and electricity grids - Macroeconomic impact to be more for developing countries
Economic losses
- A global mean average temperature rise of 2°C may lead to global aggregated economic losses between 0.2 and 2% of income
- Adaptation, management and markets will change the economic effect of climate change on fisheries and forestry
Water
- Climate change will impact, positive and negative, and varying in scale and intensity on water supply infrastructure and demand - Between the 1950s and the 1990s, the annual economic losses from large extreme events, including floods and droughts, increased 10-fold; developing countries hardest-hit - Flood damage constitutes about 33% of economic losses inflicted by
natural hazards worldwide
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The dry bed of the Stevens Creek Reservoir in California. A climate study estimates that 12 %of land will be subjected to drought by 2100 through rainfall changes alone.
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Natural disasters
Nature is a powerful force. It can change the course of history. - it can be either GOOD (e.g. giving us rain, nice breeze) - or BAD. If natural disasters (cyclones, fires, floods, drought, etc.) destroy huge gene
pools of plants, like large areas of rain forest, then we can say that genetic erosion has happened.
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Cultivation of food crops can also result in the genetic erosion of these plants. In trying to get the characteristics of the plants that we want (for e.g. higher root yield, bigger bunch, sweeter fruit), other genes in the plants are lost. Today, after years and years of changing the genes of our food crops by cultivation, the original genetic diversity in these crops is considerably reduced.
In the photo below only one type of coconut and one type of taro is planted. This area use to have different types of taro and coconuts.
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Conservation of genetic material
Community seed bank
. Extremely important in the preservation of local varieties and for agricultural production.
. Farmers rely on informal seed systems based on local growers retention of seed from previous harvests, storage, treatment and exchange of this seed within and between communities.
Field gene banks n Collection of materials and planting in the orchard or field in another
location. n Traditionally used for perennial plant species producing recalcitrant
seeds, or fewer/no seeds, having long life cycle to generate breeding, preferably stored as clonal material, e.g. banana, coffee etc.
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Conservation of genetic material Seed gene banks - Most widely used for seed conservation - Seeds are dried to low moisture content and stored at
subzero temperatures in cold stores or deep freezers. - This technique accounts for 90 percent of the 6 million
accessions conserved ex situ globally (FAO) In vitro storage Conserve species with recalcitrant seeds or species that are
vegetative propagated at low temperature Cryopreservation Conserve species with recalcitrant seeds or species that are
vegetative propagated at -1960C/liquid nitrogen
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CIMMYTT
CIMMYT
ICARDA
CIMMYT
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Doomsday Vault ß The Norwegian government is building an underground vault to guard against a major catastrophe - nuclear war, asteroid strikes or severe climate change
ßIt’s a seed bank on a wild Arctic island 500 miles from the North Pole: a store for all the known varieties of the world’s crop
ß Three separate underground chambers.
ßEach chamber has the capacity to store 1,5 million different seed samples
ß The facility is designed to have an almost “endless” lifetime.
In vitro conservation
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Research work on cryopreservation have led to the development of protocols for cryopreservation of no less than over 150 different plant species.
A wide range of species can now be routinely cryopreserved: banana (Musa spp.), peanut, cassava, bramble fruits (Rubus), pear, vegetables in the Solanum family, garlic, mint, coffee, cocoa, coconut, rubber, rice, oil palm, strawberry, citrus, and tea.
Forest trees - cryopreservation European elm (Ulmus spp.), Picea glauca, Quercus petraea, Fagus sylvatica, Aesculus hippocastanum, Araucaria excelsa, Castanea, Artocarpus, and Juglans;
Embryogenic cell lines: Pseudotsuga menziesii Picea glauca, Acer pseudoplatanus, Picea abies and Pinus taeda,
Seeds: Abies alba, Sequoiadendron giganteum, Larix decidua, Pseudotsuga menziesii, Picea abies, Pinus sylvestris,
Pollen: Betula pendula, B.pubescens, Larix decidua, L.kaempferi, Pseudotsuga menziesii, Picea abies, Pinus sylvestris, Quercus petraea and Q. robur
Encapsulated shoot tips: Eucalyptus gunnii
In vitro shoot tips: Salix hybrid, Populus tremuloides, Populus alba, Betula pendula
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Table 2. Production of spices in India (1997-98 and 1998-99) Spice crop Area (000 ha) Production (000 t) Yield (kg/ha) Export as per cent of
production
Pepper 181.5 57.3 315.6 59.7
Cardamom 72.4 5.9 81.4 4.4
Large cardamom 26.4 5.3 199.9 27.5
Chilli (red pepper) 840.6 870.7 1035.1 5.1
Ginger 77.6 252.1 3250.1 11.3
Turmeric 139.7 549.2 3931.3 4.5
Coriander 676.5 337.7 499.2 5.9
Cumin 288.5 116.3 403.1 10.4
Celery 2.9 3.6 1214.3 84.0
Fennel 27.4 36.9 1344.7 30.1
Fenugreek 38.5 49.5 1298.3 10.0
Clove 2.4 2.5 1042.4 ----
Garlic 108.8 484.4 4452.2 0.9
Nutmeg 4.8 1.4 297.1 ----
Saffron 5.7 0.02 2.8 ----
Total 2493.7 2767.5 ---- 7.9
Source: Directorate of Economics and Statistics, Govt. of India, New Delhi
Spices No. of accessions
Survival period (days)
Elettaria cardamomum 35 360
Zingiber officinale 70 360
Curcuma longa 120 360
Curcuma, Kaempferia, Alpinia, Amomum and Hedychium spp 7 360 – 450
Piper nigrum and related species 26 360
Vanilla 215 560
Seed and herbal spices (Anise, Celery, Dill, Fennel, Lavender, Marjoram, Oregano, Parsely, Sage, Spearmint, Thyme etc.)
15 150 – 360
Tree spices (Murraya koenigi, Syzygium aromaticum, Cinnamomum vernum, C. camphora)
4 200 – 360
Capsicum annuum 12 360
Acorus calamus 1 360
Pandanus amaryllifolius 1 180
Total 506
Present status of in vitro gene bank, IISR, India
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Cryoprteservation of shoot tips
1. Cryopreservation of shoot tips from in vitro plants of sweet potato [Ipomoea batatas (L.) Lam.] by vitrification- Pennycookeand Towill (2000) 2. SHOOT-TIP CRYOPRESERVATION MANUAL. Barbara M. Reed. USDA-ARS National Clonal Germplasm Repository. Corvallis, Oregon. 1999 3. Plant regeneration from Rosa shoot tips cryopreserved by a combined droplet vitrification method -Adela Halmagyi and Ina Pinker (2006) 4. Cryopreservation of in vitro-grown shoot tips of apple and pear by vitrification –Niino et al (1992)
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o t t i p r e m a i n e d g r e e n d u r i n g c u
o t t i p r e m a i n e d g r e e n d u r i n g c u
o t t i p r e m a i n e d g r e e n d u r i n g c u
o t t i p r e m a i n e d g r e e n d u r i n g c u
Shoot development and rooting from successfully cryopreserved papaya meristems. A, The shoot tip of papaya (arrows) from plantlet was excised from an in vitro plant (bar:1 mm ); B, Excised shoot tips utilized for cryopreservation (bar: 1 mm); C, After vitrification and warming, shoot tip remained green during culture and resumed growth within 1 week without forming callus (bar: 1 mm); D, Shoot tip elongated after 4 weeks (Bar: 1 mm); E, Rooting of elongated shoot occurred after 8 weeks (bar: 1 cm). TAIWAN
A
GFED
CB
Figure 2. Somatic embryogenesis in papaya. A) Immature zygotic embryo, B) Somatic embryo, C) Germination of embryos, D) Rooting of plantlets, E) Acclimatization of plantlets, F) Acclimatized plants in poly bags, G) Establishment of plants in field India
Papaya tissue culture
Plant regeneration from cryo-stored transgenic aspen shoot tip
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Fig. 4. Regrowth of somatic embryos following cryopreservation. (a) Somatic embryos before cryopreservation. (b) Direct regrowth of an embryo accompanied by newly-produced secondary somatic embryos (sse). (c) Secondary somatic embryos (sse) originated from degenerating tissue. (d) Embryo showing proliferative cotyledons but lacking axis elongation (bar = 1mm).
Encapsulated gentian axillary bud cryopreservation
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Conclusions n The conservation, distribution and
proper utilization of plant genetic diversity/resources become necessary for the development and improvement of plant cultivars for sustainable crop production
n Gene/germplasm bank establishment both at the national and international levels.
n Easy availability of germplasm to plant breeders
n In vitro cultures are suitable, e.g. somatic embryos/ cell suspension, callus, and should be able to regenerate plants without somaclonal variation.
n Plant tissue culture engineering should be developed for cost effective in vitro culture facilities in the developing countries having poor infrastructure and power shortage
Conclusion - Cryopreservation n Ideal for long-term conservation of species
with recalcitrant seeds or vegetative propagated species.
n Can be incorporated in conservation strategy provided - infrastructure & capacity building are met - repeatable protocols are optimized - accessibility to liquid nitrogen in the proximity - minimized transport costs in remotely located gene banks - commitment to maintain cryo-material through regular replenishment of liquid nitrogen
Together with the air we breathe and the water we drink, crop diversity and conservation are most fundamentally important resources for human life on earth.
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