Genetic engineering of Theobroma cacao and molecular studies on cacao defense responses

Theobroma cacao, a tropical evergreen tree, holds great economic importance for many small crop farmers in developing countries. Cultivated on over five million hectares worldwide, cocoa production is limited by three major fungal diseases. Disease has resulted in average annual losses estimated at forty percent worldwide. In Brazil alone, production dropped from 400,000 to 100,000 metric tons over the past ten years due to single fungal pathogen.; Research in plant molecular biology has developed an array of new techniques for crop improvement, including tissue culture, quantitative trait loci mapping, marker assisted selection, introduction of novel genes through genetic engineering and the use molecular techniques to investigate basic physiological mechanisms. Through my research I reported use of some of these techniques to improve the efficiency of Agrobacterium mediated transformation of cacao and further used this technique to generate transgenic cacao lines expressing a cacao class I chitinase gene. Furthermore, molecular biology techniques were utilized to initiate studies of defense responses in cacao, and investigate the expression patterns of five cloned cacao ESTs in response to infection and chemical elicitation. These studies will contribute to the development of new disease control strategies with the ultimate goal of providing alternative solutions to cocoa farmers.