|Keywords:||Genetic engineering; Abiotic stress; International Potato Center (CIP); Potato/Sweet potato.|
|Correct citation:||Jaffé, W. and Rojas, M. (1994), "Transgenic Potato Tolerant to Freezing." Biotechnology and Development Monitor, No. 18, p. 10.|
The International Potato Centre (CIP, by its Spanish acronym)
has been working for years on the development of frostresistant varieties
of potato. In many Andean agricultural systems, frost substantially hinders
potato production. Crops have their specific temperature requirements and
the geographic distribution of crops is linked to altitudinal belts. Temperatures
below 0oC imply crop loses for most cultivars,
including potato, whose optimum soil temperature has been estimated to
be as high as 2023oC.
CIP has been screening and selecting potato cultivars able to resist temperature shocks of 4oC. Up to 1991, 2,000 cultivars had been screened and 537 clones selected at CPI's research station in Cajamarca, Peru. Most if not all of this research has been done by means of conventional techniques. The process, however, has been slow and complicated.
CPI's interest in cold tolerance has led to an application of biotechniques aiming at the development of coldtolerant potato cultivars through the introduction of a flounder (type of flatfish) antifreeze protein. This initiative was a cooperation between the University of Louisiana, the Central University of Venezuela and the Programa de Investigación en Papa (PROINPA) programme at the Instituto Boliviano de Tecnologia Agropecuaria (IBTA), one of the public agricultural research institutes in Bolivia, with the promotion and technical support of CIP and financing from the Andean Development Bank.
It has been known since the early eighties that a flounder, Pseudopleuronectes americanus, can survive temperatures of 1.5oC. Several genes that codify for different antifreeze proteins (APs) have been isolated from this fish. These proteins are in the fish blood and protect it from freezing. The APs concentration in the fish's blood varies along the year. Their production starts in autumn, reaching the highest concentration during winter time, and descending again in springtime.
The group of the University of Louisiana successfully used genetic engineering techniques to find out whether these proteins would have the same protective effect in plant cells. Based on the Agrobacterium mediated genetic transformation technique, they constructed a plasmid containing a gene coding for one of these APs. The gene was placed between two marker genes permitting the selection of transformed plants.
The Venezuelan group introduced the plasmid supplied by the University of Louisiana group into strains of Agrobacterium rhizogenes. These bacteria are used as vectors to carry the genetic information of the selected AP into potato plant cells. Infecting potato plant tissue with these strains, the AP gene has been transferred to a group of potato clones.
After the regeneration of complete plants by the use of in vitro
culture, molecular tests confirmed the presence of the antifreeze
gene in the regenerated plants. The efficiency of the transformation varied
according to the genotype of the potato clones.
The transgenic potato clones were transferred to Bolivia, and multiplied. Since 1993, the PROINPA group is testing the new varieties in a contained green house. Preliminary results indicate that a level of cold tolerance has been achieved. The next step should be field tests, which require a biosafety evaluation and clearing by national regulatory authorities. Bolivia has some experience with field releases. National biosafety guidelines have been drafted, and transgenic cotton varieties have been tested.
The commercial introduction of these clones, in case the agronomic evaluation
warrant such a step, faces interesting questions of intellectual property
and commercial distribution. They will be an important challenge for Bolivia's
(and perhaps also Venezuela's) legal and commercial systems related to
This cooperative project shows the potential of international cooperation in transferring generic technologies to developing countries. The Venezuelan group now has some incipient capabilities for plant transformation, using the Agrobacterium alternative. The group aims at the complement of this capability as soon as possible with genetic engineering expertise, e.g. constructing the plasmids.
Walter Jaffé/Miguel Rojas
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