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= Low Cost Tissue Culture =

Summary
The primary application of micropropagation has been to produce high quality planting material Low-cost tissue culture technology is the adoption of practices and use of equipment to reduce the unit cost of micropropagule and plant production. Low cost options should lower the cost of production without compromising the quality of the micropropagules and plants. In low cost technology cost reduction is achieved by improving process efficiency and better utilization of resources. Low-cost tissue-culture technology will stay a high priority in agriculture, horticulture, forestry, and floriculture of many developing countries for the production of suitably priced high quality planting material.

INTRODUCTION
Hundreds of commercial micropropagation laboratories worldwide are currently multiplying large number of clones of desired varieties and local flora. Apart from the rapid propagation advantage, this technology is being used to generate disease-free planting material, and has been developed and applied to a wide range of crops, and forest and fruit trees. However, in many cases, the cost of micropropagule production precludes the adoption of the technology for large-scale commercial propagation.

THE NEED FOR LOW COST TECHNOLOGY
Low-cost tissue culture technology is the adoption of practices and use of equipment to reduce the unit cost of micropropagule and plant production. In many developed countries, conventional tissue culture-based plant propagation is carried out in highly sophisticated facilities that may incorporate stainless steel surfaces, sterile airflow rooms, expensive autoclaves for sterilization of media and instruments, and equally expensive glasshouses with automated control of humidity, temperature and day-length to harden and grow plants. Many such facilities established at a high cost are high-energy users, and are run like a super-clean hospital. The requirements to establish and operate such tissue culture facilities are expensive, and often are not available in the developing countries. For example, the cost of electricity in the developed countries is much lower, and its supply far better assured than in the developing countries. The same can be said of the supply of culture containers, media, chemicals, equipment and instruments used in micropropagation. Hence, alternatives to expensive inputs and infrastructure have been sought and developed to reduce the costs of plant micropropagation.

ADOPTION OF LOW-COST OPTIONS
Low cost options should lower the cost of production without compromising the quality of the micropropagules and plants. The primary application of micropropagation has been to produce high quality planting material, which in turn leads to increased productivity in agriculture. The generated plants must be vigorous and capable of being successfully transplanted in the field, and must have high field survival. In addition, they should be genetically uniform, free from diseases and viruses, and price competitive to the plants produced through conventional methods. Reducing the cost should not result in high contamination of cultures or give plants with poor field performance. The foremost requirement of micropropagation is the aseptic culture and multiplication of plant material. Microbe-free conditions need to be maintained in culture containers, and during successive subcultures. In many cases, mistakes in concept or practice can introduce microbes in the culture containers from an external source or the plant material itself (endophytic contamination). As a result, the microbes overgrow the cultures, and wipe them out. Microbes may grow slowly under controlled low temperature, but they proliferate very fast under uncontrolled and high temperature. Thus the adoption of wrong low-cost options may make the production process prone to disasters. Low cost techniques will succeed only if the basic conditions for tissue culture are scrupulously adhered to maintain propagule quality. Microbial contamination of cultures is known to wipe out work of months, and can turn into a nightmare. The best low-cost option is to discard and dispose of contaminated cultures outright. Avoiding contamination in small R&D laboratories is not a difficult task where only a low number of cultures are handled. However, commercial production involves handling of thousands of cultures each day. It is also essential to maintain such cultures in large numbers under contamination-free conditions, until they are used for either further subculture or hardening and growing-on. Plants do not have an immune system and there is a limitation on the use of antibiotics to circumvent the problem. Moreover, many of the antibiotics, which are effective against bacteria, fungi, and phytoplasmas, are toxic to plants as well. Obviously, the use of antibiotics is not foolproof or the desired method to rid microbial contamination (Pierik, 1989). Sophisticated state-of-the-art facilities are not a guarantee for prevention of contamination. The laboratories that succeed in an immaculate control of contamination do so by adherence to scrupulous techniques of basic tissue culture. Thus, it is not the sophistication but the procedures that ensure the quality of tissue cultured plants.

QUALITY OF MICROPROPAGULES
Low cost technology means an advanced generation technology, in which cost reduction is achieved by improving process efficiency, and better utilization of resources. Presently, both the developing and the developed countries require low cost technology to progressively reduce the cost of propagule production. In many developing countries, the potential end-users of plants derived from tissue culture have been the resource-rich farmers. They know the benefits and potential of healthy planting material. Such growers are prepared to risk investment in the high productivity potential of the planting material. For example, hybrid seeds of many vegetables, papaya, rice, and cotton cost 15-20 times more than the price of ordinary varieties. Yet there is a wide market for them. Hence, the production of low quality plants, just because they are less costly, is not going to be a sustainable approach for the application of micropropagation in agriculture. Lowering of cost of production is possible only if the methods do not compromise the basic imperatives of tissue culture and quality of plants.

IMPORTANCE OF LOW COST TECHNOLOGY
The potential of plant tissue culture in increasing agricultural production and generating rural employment is well recognized by both investors and policy makers in developing countries. However, in many developing countries, the establishment cost of facilities and unit production cost of micropropagated plants is high, and often the return on investment is not in proportion to the potential economic advantages of the technology. These problems can be addressed by standardizing agronomic practices more precisely (precision agriculture) and by achieving maximum net profits from the crops or by decreasing the unit cost of production or both. The technology is particularly relevant to the propagation ofornamental plants. Despite high costs of production, trading of ornamental plants has thrived because they command high unit value. However, the market is limited. Over a period of time, many new tissue-culture companies in several developing countries have entered to compete in the limited market. The inevitable result has been the reduction of net margins below viable limits. Many international organizations also agree that tissue culture technology is very relevant to agriculture, provided the problem of high cost of production is satisfactorily solved. The role of tissue culture was clearly recognized by the FAO (1993) in the paper on ‘Biotechnology in agriculture, forestry and fisheries - FAO's Policy and Strategy’. The report pointed to the wide use of tissue culture techniques for multiplication of elite clones and elimination of pathogens in planting material. It also pointed to the successful tree regeneration in about 100 forest species and its value for breeding, clonal testing and rapid deployment of superior genotypes. Several R&D projects have been undertaken to improve the productivity of agricultural, horticultural and forest trees by the European Union under Co-operation in the Field of Scientific and Technical Research (COST). Under this program, coordinated and funded by the European Union, one of the primary aims has been to reduce micropropagation cost. For example, the objective of ‘COST 843’ action has been the innovation of low-cost plant propagation methods that enhance sustainable and competitive agriculture and forestry in Europe (COST Action, 2001). The high costs of labour of micropropagation are a major bottleneck in the EU to fully exploit in vitro culture technology. In the EU, labour currently accounts for 60-70% of the costs of the in vitro produced plants. In another program, the large-scale production and introduction of bamboo in the EU using tissue culture technology has been undertaken with the main objective of reducing the costs of micropropagation.

FUTURE ROLE
It has been stressed time and again that in the long-term agriculture and forestry need to be sustainable, use little or no crop-protection chemicals, have low energy inputs and yet maintain high yields, while producing high quality material. Biotechnology-assisted plant breeding is an essential step to achieve these goals.

Plant tissue culture techniques have a vast potential to produce plants of superior quality, but this potential has been not been fully exploited in the developing countries. During in vitro growth, plants can also be primed for optimal performance after transfer to soil (Cf. Chapter 9). In most cases, tissue-cultured plants out-perform those propagated conventionally. Thus in vitro culture has a unique role in sustainable and competitive agriculture and forestry, and has been successfully applied in plant breeding, and for the rapid introduction of improved plants. Bringing new improved varieties to market can take several years if the multiplication rate is slow. For example, it may take a lily breeder 15-20 years to produce sufficient numbers of bulbs of a newly bred cultivar before it can be marketed. In vitro propagation can considerably speed up this process. Plant tissue culture has also become an integral part of plant breeding. For example, the development of pest- and disease-resistant plants through biotechnology depends on a tissue culture based genetic transformation. The improved resistance to diseases and pests enables growers to reduce or eliminate the application of chemicals.

The FAO Committee on Agriculture has perceived plant tissue culture as a main technology for the developing countries for the production of disease-free, high-quality planting material, and its commercial applications in floriculture and forestry (FAO, 1999). It further points out that tissue culture techniques are being used particularly for large-scale plant multiplication. Micropropagation has proved especially useful in producing high quality, disease-free planting material for a wide range of crops. Tissue cultured based industry also generates much-needed rural employment, particularly for women.

In forestry, the availability of tissue culture linked production systems may effectively provide sustainable alternatives to the need for harvesting wood from native forests and natural habitats. Successful protocols now exist for the micropropagation of a large number of forest tree species, and the number of species for which successful use of somatic embryogenesis is increasing. Thus in the future, it is likely that micropropagation in the forestry sector will become commercially important. Compared to vegetative propagation through cuttings, the high multiplication rates available through micropropagation offer a much quicker capture of genetic gains obtained in forest tree breeding programs. However, the current high costs will also be one of the major impediments to the direct use of micropropagation in many programs.

The broad application of existing technologies to plantation species is important for tree improvement in the tropics (Haines and Martin, 1997). In a small number of plantation programs, micropropagation is being used as an early rapid multiplication step. However, it has been pointed out that the current high costs will be an impediment to the direct use of micropropagules as planting stock. Micropropagation clearly has a role, in the rapid multiplication of the selected clones for conventional production of cuttings. The direct use of micropropagules as planting stock in industrial plantation can dramatically broaden forestry tree farming if propagation costs are reduced. The availability of micropropagation technologies will also be useful in genetic engineering applications, e.g., the production of plants as a source of “edible” vaccines. There are many other useful plant-derived substances which can be produced in tissue cultures, sometimes more cheaply and reliably than from natural forests and plantations. These include medicinal compounds and drugs now being sought in major prospecting operations in the tropical forests.

Micropropagation has been identified as a suitable technology in the development projects of UNESCO in Africa and the Caribbean; however, the cost of production must be reduced (Brink et al., 1998). Practically in all developing countries, the private industry is the most important group that requires cost-effective technology. For example, in India of the 90 commercial micropropagation units established initially, 32 were closed down. Of those engaged in commercial production, many are uneconomic mainly due to the high cost of production (Anonymous, 2002) and the absence of quality tests. Hence, low-cost tissueculture technology will stay a high priority in agriculture, horticulture, forestry, and floriculture of many developing countries.