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Medicinal Plant Conservation

P. Pushpangadan and Jacob Thomas

Tropical Botanic Garden and Research Institute
Pacha-Palode, Thiruvananthapuram - 695 562, Kerala, India


Home | Contents | Abstract | Medicinal Plant Conservation | Conservation of Medicinal Plants at TBGRI | Conservation Research and Public Awareness | Acknowledgements | References


Abstract

Tropical Botanic Garden and Research Institute (TBGRI). Palode over these years has given great emphasis for the conservation and sustainable utilization of the medicinal plant wealth of the peninsular India apart from all other wild plants and has developed a display garden, a field gene bank and an in vitro gene bank including a seed bank for their conservation 'Simulated' in situ field gene bank development has been postulated as a novel approach for conservation of medicinal and aromatic plants by bridging in situ and ex situ means. Sampling criteria, characterisation and related conservation research, creation of public awareness etc undertaken at TBGRI are also briefly described.

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Medicinal Plant Conservation

Medicinal plants continue to be an important therapeutic aid for alleviating ailments of humankind. The importance of plant based medicine waxed and waned during the last 200 years. Advancements made in synthetic chemistry along with the discovery of antibiotics and cortico-steroids and their artificial synthetics caused rapid decline of plant based medicines particularly in the developed nations during the century. The developing nations depend on the other hand mostly on plants for their medicine. In recent times, however, due to the increasing realization of the health hazards and toxicity associated with the indiscriminate use of synthetic drugs and antibiotics, there has been a renewal of interest in the use of plants and plants based drugs throughout the world. According to WHO, the resurgence of public interest in traditional medicine is on the increase because of a sweeping green wave and a large number of plant drugs are now sold in the 'health food shops' all over the world including the developed world (Pushpangadan and Narayanan Nair, 1997). The preventive and promotive aspects of the Eastern traditional systems of medicine particularly that of India and China are finding increased popularity and acceptance through out the world and scope for developing plant based drugs assumes greater significance at a time when modern medicine has failed to provide cure for the dreadful diseases like cancer, AIDS, arthritis, liver diseases and other diseases of unknown etiology.
The resurgence of public interest in plant based medicine coupled with the rapid expansion of pharmaceutical industries have necessitated an increased demand for medicinal plants leading to over-exploitation that threaten the survival of many rare species. Confronted by such unprecedented genetic loss, disappearance of species and ecosystems conservation of our national heritage assumes paramount urgency. According to a recent study carried out by scientists of Tropical Botanic Garden and Research Institute (TBGRI), over-exploitation and unsustainable harvesting of medicinal plant resources are posing great danger to the survival of several invaluable plant species in the wild. Habitat degradation due to increased human activities (human settlements, agriculture and other developmental projects), illegal trade in rare and exquisite plant species and loss of regeneration potential of the degraded forests have further accelerated the current rate of genetic erosion and species extinction. TBGRI team has listed 19 critically endangered medicinal plants in Kerala, the southern most state in the Indian Union. Considering the rapid loss of medicinal plants various measures has been initiated in India for conserving and sustainably utilizing the medicinal plant genetic resources.

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Conservation of Medicinal Plants at TBGRI

Conservation of all wild plant genetic resources of the tropical regions of India is the main mandate of TBGRI and medicinal plants constitute an integral part of this programme. Focusing the local priorities in the background the conservation efforts of medicinal plants at TBGRI are in the following lines.

Under the medicinal plant Conservation Programme, TBGRI has adopted and developed a three way approach, viz.

  1. A medicinal plant display garden
  2. A field gene bank and
  3. In-vitro gene bank including a seed bank.

1) Medicinal Plant Display Garden

Spread over 25 acres, the medicinal plant display garden houses over 2750 medicinal plants representing almost all plants used in various indigenous systems of medicine like Ayurveda, Siddha, Unani and oral local health traditions including the tribal medicine. The purpose of this garden is mainly to educate the public visiting the garden. All plants are provided with self explanatory display notes containing scientific name, common names in English, Hindi/Sanskrit and also the local vernacular - Malayalam along with important medicinal uses. There is also a special display section in this garden where the medicinal plants are grouped according to major Ayurvedic polyherbal formulations such as 'Dasamoolam', (involving 10 plants) 'Chavanaprasam' (involving 47 plant spp.) and Ayurvedic taxonomic grouping of plants like 'Trikatu', 'Chaturjatham', 'Ambashtatiganam', 'Vallipanchamoolam' etc. These form some of the interesting attractions for the visitors. Medicinal plants used in modern medicine, homoeopathy etc. are also displayed.

2. Field Gene Bank

As a part of the G-15 GBMAP programme (Establishment of Gene Banks for Medicinal and Aromatic Plants), three national gene banks were established by Govt. of India. Of these one is functioning at TBGRI and the other at NBPGR (New Delhi) and CIMAP (Lucknow). The major mandate of the Gene Bank at TBGRI is short to medium term and long-term conservation of the genetic diversity of medicinal and aromatic plants of peninsular India through the organization of field gene bank, seed bank, in vitro tissue/cell repository and cryobank.

TBGRI has experimented a novel field conservation method by combining in-situ and ex-situ means into a single complementary and compatible frame work as a viable option to achieve the most tangible results of plant conservation especially for medicinal and aromatic plants. Bridging in situ and ex situ is essentially a habitat recreation simulating a natural ecosystem in a similar agroclimatic zone or near or around in a degraded forest patch or ecosystem eroded after clear felling or areas abandoned for shifting cultivation. Unfortunately habitat reconstruction is a poorly researched subject which relies more on practical demonstration than science. But, to be successful, it depends critically up on an understanding of the ecological principles governing the habitat to be reproduced, the characteristics of the site, the individual species to be introduced, the association and their mutual interaction etc.

A protected , degraded but densely regenerated forest plot (in-situ) of 75 acres with natural populations of several important plant species has been selected in TBGRI campus for the field gene bank development activities. This area, once an evergreen forest, was clear felled for converting into plantations of Eucalyptus and Cashewnut some 50 years back.. Adjacent to this plot lies a natural, relatively undisturbed evergreen to semi-evergreen forest. After felling the plantations in 1982 this piece of land was handed over to TBGRI in 1983. The characteristic landscape of this region was typical of the Western Ghat mountain system with the undulating hills of different latitudinal gradients, slopes and valleys offering varied sites for forming micro-ecological niches with varying assemblages and associations of organisms.

TBGRI preserved the area as such and gave physical protection from any human intervention. After 10 years when the flora of this regenerated forest was analysed, hardly 15 to 20% of the original species complex could be located. Plants like Terminalia paniculata, T. alata, Artocarpus hirsutus, Calophyllum apetalum, Cassia fistula, Dillenia pentagyna, Hopea parviflora, Humboldtia vahliana, Madhuca neriifolia, Mesua nagassarium, Pterocarpus marsupium, Myristica malabarica, Olea dioica, Aporusa lindleyana, Careya arborea etc. became the most common and dominant among tree species. A programme to recreate this forest in the original form by introducing the missing plants was initiated in 1993 to develop a miniature but tropical Western Ghat ecosystem with all possible floristic components.

The field gene bank programme of medicinal and aromatic plants was integrated in this programme. It in essence is nothing but a simulation of the natural vegetation. A careful study of the adjacent natural forest, which is fairly undisturbed, made it possible to simulate vegetation pattern/structure during the exercise. Association pattern of abiotic preference and formation of micro habitat or micro ecological niches as found in similar forest area was carefully studied and the same was simulated in this field gene bank.

Introduction of species were done carefully considering various factors peculiar to the natural habitats such as ecological situations, associations with other plants and micro organisms, soil characteristics, vegetation type etc so that a symbiotic balance is achieved in each community of plants in a short period of time. In due course the succession process starts in the man made populations and may end up with natural evolution taking over.

In this exercise we have developed a number of so called simulated in-situ field gene bank plots accommodating nearly 50,000 accessions of about 2500 angiosperm plant species/varieties which include 100 endemic, RET- MAP from the Western Ghat region. All possible samples including a broad spectrum of the genetic variants, cytotypes and cheomotypes of the target species; in 50-1000 specimens each - depending on the variability were introduced and maintained in the field gene bank.

To prevent inter breeding and to preserve the variability each accession is planted at least 100-200 meters apart, with other plants in between serving as natural barriers. The species complex thus reconstructed now reached almost 50% of the original species density of a near forest ecosystem. This simulated/recreated ecosystem is essentially now becoming a miniature biosphere reserve with representative species complex of the Western Ghat flora. It cannot be still termed a biosphere reserve because of the very small size of the ecosystem.

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Sampling

Appropriate random methods were adopted for initial sampling to capture and represent the variability within and between populations of a species. In the case of endangered populations, care has been taken while collecting not to significantly hazard the survival of the population. In cases where only a few individuals alone are left in natural population, as in the case of Janakia arayalpathra (a critically endangered endemic species with hardly 200 plants in nature) cuttings from all the 200 individual plants were procured and introduced in an area in the field gene bank after rooting where the natural rocky habitat of this species was simulated.

Populations of these 200 individuals did not show much variability except in their chemical composition. The identifiable variants were multiplied by tissue culture methods and a large population numbering 1000 plants were introduced and got established in the field gene bank. Collection of numerous plants truly representative of population is usually impossible or most undesirable for obvious reasons in several cases.

Collections based on seeds can resolve many of the related problems as they are usually produced in large numbers; sufficient numbers may be collected with minimum or even no significant hazard to the parent populations. Representation of genetic diversity (by having a large populations), prevention of genetic erosion (by avoiding selections), preservation of genetic integrity (by giving no chances of gene flow), retention of gene frequencies (by not allowing any distortions to breeding patterns) and guarantee for long-term security (with minimum inputs): the essential requirements for collection and maintenance of plant genetic resources (Thompson, 1979), were given adequate attention in our processes for developing the gene bank.

Morphological, chemical, cytological and or genetical screenings were carried out on the initial samples for identifying potential accessions for conservation in the gene bank. Isozyme analysis, DNA fingerprinting and or other appropriate studies are also initiated on seedlings raised from seed samples to identify the genetic variants for introduction in the gene bank. Important rare and endangered medicinal and aromatic plants introduced in the field gene bank so far included Acorus calamus, Adathoda beddomei, Alstonia venenata, Aristolochia tagala, Baliospermum montanum, Coleus forskholii, Coscinium fenestratum, Curcuma aromatica, C. zeodaria, Cymbopogon flexuosus, Embelia ribes, Eryngium foetidum, Ficus macrocarpa, Geophila reniformis, Gloriosa superba, Holoptelia integrifolia, Holostemma annulare, Hydnocarpus macrocarpa, Janakiya arayalpathra, Nervilia prainiana, , Nilgirianthus ciliatus, Piper attenuatum, P. barberi, P. brachystachyon, P. hapnium, P. trichostachyon, Rauvolfia micrantha, R. beddomei, Terminalia arjuna, T. belerica, T. chebula, Trichopus zeylanicus, Zingiber zerumbet etc.

3) Invitro Methods

In addition to the above said ex-situ methods the following in vitro measures are also being set up for conservation of most rare and endangered medicinal plants.

  1. Seed bank (at - 20oC) for short-term to medium-term conservation of species through seeds collected from medicinal plants of peninsular India.
  2. A mericlone bank of 50 selected rare and endangered species of medicinal plants along with their intra-specific variants.
  3. A Cryobank for 12 most endangered medicinal and aromatic plants.
  4. Develop facilities and conduct research on short, medium and long term conservation of MAP using pollen, embryo and seed culture of plants for which conventional methods of storage are unsuccessful or inadequate like recalcitrant species.

We have also undertaken activities such as characterization of the medicinal plants : morphological, cytological, chemical and molecular including at DNA level, to prepare passport data for all rare and endangered and endemic medicinal plants of tropical India. In order to extend the benefits of the conservation programme to the community we have started programmes for: developing skilled manpower in ex-situ and in vitro conservation methodologies, developing a national database on tropical medicinal and aromatic plants, multiplication and reintroduction into natural habitats and supply of genuine plant materials to farmers, local traditional physicians, NGOs etc.

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Conservation Research and Public Awareness

A Conservation biology division functions at TBGRI to study the causes of extinction of natural species and develop appropriate mitigatory measures to conserve the species. The science of conservation biology offers tremendous insights into the conservation and sustainable management of genes, species, populations and ecosystems that are facing imminent threat and extinction. The mandate of the conservation biology division at TBGRI include:

  1. Ecophytogeographic survey and screening of rare and endangered medicinal and aromatic plants to locate and assess the extent of genetic variability and species population.
  2. Integrated field research in taxonomy, phytogeography and plant population biology.
  3. Identification of extrinsic and intrinsic factors that cause rarity, endangerment and extinction of species/populations and
  4. Appropriate conservation methods along with sufficient strategies for sustainable utilization of medicinal plants.

Training and public awareness programmes are equally significant in conservation and rational utilization of medicinal plants. Botanic gardens can serve as information centres for the scientific community and local people, plant collectors and other who depend on medicinal plant resources. Such an initiative would help in inculcating better awareness among people on the economic, ecologic and ethical significance of conserving medicinal plants and thereby avoiding over-exploitation and wastage; efficient, optimal and sustainable use of these precious resources.

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Acknowledgements

The authors are thankful to the Dept. of Biotechnology, Ministry of Science & Technology, Govt. of India for providing financial assistance for the gene bank development.

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References

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