Bibliography

Cassava is a vegetatively propagated crop and its improvement through conventional breeding is challenging due to its high heterozygosity and low fertility. As it has not been possible to solve all cassava's problems connected to agriculture and consumption by traditional breeding, another solution could be to use molecular breeding. Major deficits of cassava are low protein content in the tubers, rapid post-harvest tuber deterioration and high content of cyanogenic glucosides. Careful processing of cassava roots is required to remove the released hydrogen cyanide which can cause acute or chronic cyanide intoxication. Unfortunately, processing to remove hydrogen cyanide typically results in loss of protein, minerals, and vitamins. For successfull molecular breeding of cassava, a genotype-independent genetic transformation method is essential. So far it has only been possible to transform model lines which have limited agricultural importance. Here a regeneration and transformation method is presented which has been successfully applied to all African varieties tested so far with a transformation frequency ranging from 0.2% to 3.8%. The method is based on the procedure developed by Li et al. (1996). This method is among others now used to 1) produce acyanogenic cassava (Jørgensen et al 2005), 2) improve the nutritional value in the tubers, 3) virus resistance. The improvement of the nutritional value is focused on increasing the protein content in the tubers in varieties with and without a naturally increased levels of pro-vitamin A.