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Africa, including South Africa, is faced with a
problem of increasing rural poverty that leads to increasing urbanisation,
joblessness, crime, food insecurity and malnutrition. Root and tuber crops such
as sweet potato and potato, as well as cassava and indigenous potato are
important crops for food security. The latter are also important due to their
tolerance to marginal conditions. Potato and sweet potato are of great economic
value in South Africa, with well-organised marketing chains and, for potato, a
large processing industry. There is one cassava starch extraction factory in
operation in South Africa. A number of diseases are of importance in potato in South Africa: early blight, late blight, bacterial wilt, scab and virus. Insect pests such
as tuber moth and leaf miner are also constraints. In sweet potato the
occurrence of viruses and weevils, as well as the availability of healthy
planting material are the most important limiting factors in production.
African Cassava Mosaic Disease (CMD) caused by a virus, is a problem in growing
cassava. Plant biotechnology applications offer a number of sustainable
solutions. Basic applications such as in vitro genebanking where large
numbers of accessions can be maintained in a small space, meristem cultures to
produce virus-free plants and mass propagation of popular cultivars in order to
make planting material available for sustainable production. More advanced
biotechnology applications that may be of value are molecular marker technology
and genetic engineering. The latter can play a role in overcoming virus and
potato tuber moth in potato, in resistance to CMD in cassava and possibly in
sweet potato to incorporate virus and weevil resistance.

South African Journal of Botany
2004, 70(1): 60–66