IN VITRO  CONSERVATION OF GENETIC RESOURCES


Brian V. Ford-Lloyd
University of Birmingham, UK




The maintenance in vitro of plant material has an 
important role to play as an alternative to field 
genebanks in conserving clonally propagated species (eg. 
potato, cassava, yam, taro, cocoyam, banana, garlic), and 
those species which produce recalcitrant seeds (eg. cacao, 
mango, coconut, avocado, hops). Increasingly, in vitro 
conservation is even required for seed crops as barley, 
rice and maize, where because the possibility for 
transformation in governed by genotype, there is a need to 
conserve competent cell cultures for continued 
experiments.

Various techniques now exist for in vitro conservation 
including slow grwth storage and cryopreservation, the 
latter being the most promising for long-term conservation 
of germplasm. While slow growth storage is dependent upon 
the ability to culture shoots under conditions which 
reduce the growth rate to a minimum, cryoperservation 
depends upon the manipulation of meristems, callus, cell 
cultures or somatic embryos. Success may depend upon 
preconditioning, cryoprotection, rate of freezing, and the 
use of vitrification and dessication strategies before 
storage.

In vitro storage of germplasm of potato, cassava and 
banana is now underway. Research continues to find ways of 
conserving mango, coconut and Xanthosoma. In vitro 
techniques for collecting germplasm are well advanced and 
have beebn succesfully applied to cotton, cassava, coconut 
and citrus fruits.

Genetic stability of germplasm stored in vitro culture, 
and may occur at very high levels. For instance, in 
bananas and plantains up to 60% of in vitro progeny can be 
offtypes. Despite this, in vitro techniques are still 
preferred for propagation and maintenance of germplasm. 
Because of the significance that in vitro techniques have 
in Musa germplasm conservation and propagation, a case 
study of bananas and plantains is worthy of deeper 
consideration.


References


Dodds JH. 1991. In vitro methods for conservation of plant 
genetic resources. Chapman and Hall, London.


Ford-Lloyd B, Jacjson M. 1986. Plant Genetic Resources -an 
introduction to their conservation and use. Edward Arnold, 
London.


Vuylsteke DR. 1989. Shoot-tip culture for the propagation, 
conservation and exchange of Musa germplasm. Practical 
Manual for Handling Crop Germplasm in vitro. 2. IBPGR. 
Rome.


Withers LA. 1989. In vitro conservation and germplasm 
utilization. In: The use of plant genetic resources. Brown 
AHD, Marshall DR, Frankell OH and Williams JT (eds.). 
Cambridge University Press. Cambridge, pp. 309-334.


Withers LA. 1991. In vitro conservation. Biol. J. Linn. 
Soc. 43:31-42.