Conserving biodiversity

WITH THE destruction of the natural environment, the genetic diversity of both domesticated crops and their wild relatives is being rapidly eroded. Scientists have realised tissue culture is a powerful tool to conserve biodiversity.

Says K P Chandel, joint director of the National Bureau for Plant Genetic Resources (NBPGR) and head of its plant tissue culture repository, "Tissue culture and in vitro farms, developed in laboratory test tubes, would be an insurance against the complete loss of genes that may be useful in the future."

Financed by the department of biotechnology, the National Facility for Plant Tissue Culture Repository (NFPTCR) was set up at NBPGR in 1986. It has accorded priority to five plant types -- tubers, bulbs, spices and plantation crops, horticultural crops and medicinal and aromatic plants. Each plant requires a separate methodology, which "is a time-consuming process. We have to test each culture and ensure that adult plants are viable," says an NFPTCR expert.

"Tissue culture becomes important especially when germplasm collections of vegetatively reproducing plants -- tubers and yams, for example -- are to be maintained. Their seeds cannot be conserved, but we try to keep the plant material alive as long as possible," says Chandel. Seeds with a high moisture content that cannot be desiccated for storage, pollen and some plant tissue cultures that cannot be stored using normal methods are conserved in liquid nitrogen.

NFPTCR scientists have been somewhat successful in developing techniques for medium-term storage (1-2 years) of germplasm. Shoot cultures of banana, ginger and sweet potato can be maintained for 8-12 months and greater yam can be conserved for some two years in in vitro farms. More than 120 banana varieties are being maintained and safeguarded from pests.

In 1985, the ministry of environment and forests initiated a project to conserve endangered species of plants using tissue culture technology. Medicinal plants were the main focus of this project. Simple, quick and reliable tissue culture protocols were developed for multiplying certain Himalayan plants. Efforts were made to reintroduce these plants into their original environment, but it is still too early to predict the chances of survival.