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Field performance of a biotech potato with late blight resistance in Uganda

Marc Ghislain: International Potato Center

<div>The most devastating potato disease is late blight (LB) caused by <em>Phytophthora infestans</em> (Pi) and is still responsible for significant losses which may reach 30-75% for small-scale potato farmers in sub-Saharan Africa. Added to the cost of fungicide, SSA farmers realize barely 40% of the value of their potential production. Breeding for LB resistance has been met with challenges of durability of resistance. Instead, we have transferred three resistance genes isolated from wild potato relatives (<em>RB</em>, <em>Rpi-blb2</em> from <em>Solanum bulbocastanum</em> and <em>Rpi-vnt1.1</em> from <em>S. venturii</em>) into four cultivated potato varieties ‘Desiree’, ‘Victoria’, ‘Tigoni’ and ‘Shangi’ using genetic engineering. Transgenic events with extreme resistance to LB have been tested in confined field trials (CFT) in Uganda. All transgenic events tested grew normally and produced expected yield without any fungicide spray during three seasons. Remarkably, not a single lesion was observed at any stage of plant development. Fine molecular characterization of the T-DNA structure and insertion site for selected transgenic events from the variety ‘Victoria’ (known in Kenya as Asante) is underway. Multilocational CFT to conduct regulatory studies have already been initiated to assess risks to human (animal) and the environment. After this phase is completed, commercial release will be sought from national authorities. These biotech potatoes offer a durable cost-effective and environmentally-friendly solution to the control of LB disease in potato.</div>

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