We propose a biotechnological approach to improve pest and disease resistance and reduce pesticide use in potato production by metabolic engineering of natural biopesticides in the form of glucosinolates into potato. Glucosinolates are defence compounds naturally produced in Brassicales. Delivery of these biopesticides directly by the crop itself has great potential as one of several components of integrated pest management. The project is inspired by traditional Andes co-cultivation of potato and mashua, where the mashua exerts a protective role due to its benzylglucosinolate content. This project which includes engineering of a multi-gene pathway in a foreign host plant is ambitious, but realistic as we have had a major scientific breakthrough in a recent DANIDA-financed project (2004-2007), where we demonstrated that it is possible by transiently expression of 5 biosynthetic genes to make tobacco produce benzylglucosinolate. In addition, we have introduced three of the genes stably into potato. In the present proposal, we aim to complete the engineering of benzylglucosinolate genes into stable transgenic potato plants. The genetically engineered potato plants will be characterized with respect to fitness as well as pest and pathogen resistance. The plants will be tested against major potato pests such as Phytophthora infestans and the Andean weevil in contained greenhouse trials. Impact on non-target organisms such as aphids and the parasitoid leaf minor fly will be analyzed as an important component of risk assessment of environmental biosafety. The project will bring together experts from Danish plant science, an international CGIAR institute (Centre International Potato) and a university in Lima, and provide the possibility for doctoral training to a talented Peruvian PhD student. The project may provide an important step towards sustainable potato production. This is in agreement with the launching by UN of 2008 as International Potato Year aimed at focussing world attention on the role that potato can play in providing food security and alleviating poverty. Furthermore, the project has major potential within agro-biotechnology, which is an important future means to meet the demands for biomass food and energy for the world population.
Project Completion Report:
The defense-related plant metabolites known as glucosinolates play an important role in agriculture, ecology, and human health. Despite an advanced biochemical understanding of the glucosinolate pathway, the source of the reduced sulfur atom in the core glucosinolate structure remains unknown. Our results from this nproject demonstrate that GSH is the sulfur donor in the biosynthesis of glucosinolates. This knowledge is important for engineering of glucosinolate production into heterologous hosts.
With the gained knowledge on biosynthetic enzymes in the pathway, metabolic engineering to produce benzylglucosinolate in tobacco has been performed. First, the last three Renes of the glucosinolate pathway from Arabidopsis thaliana were transferred into tobacco using a single polycistronic expression construct driven by a high constitutive promoter. Retransformation of a selected transgenic line carrying this first construct with the polycistronic construct containing the first three genes of the gfucosinolate pathway driven by the promoter of the green tissue-specific rubisco small-subunit, resulted in the generation of benzylglucosinolate-producing transgenic tobacco plants,