Potato Review

16 POTATO REVIEW MARCH/APRIL 2020 CUPGRA 2019 CONFERENCE Building resilience T he project started more than 20 years ago with some basic science, with the vision of addressing real problems in the eld. At the time, the timely target was late blight, as it was – and is – a very important disease. More recently, in 2015, funded by BBSRC, the Jones team began to combine genes they had isolated that confer resistance to late blight as part of a drive to build a resistant Maris Piper potato. Other traits, such as reduced bruising and browning and potato cyst nematode (PCN) resistance were also included in the project. However, the PCN genes did not work well enough to pursue, he noted. Prof Jones and his team identi ed genes which confer late blight resistance from wild potato relatives such as Solanum venturii, which have then been put together in a three-gene stack to deliver strong blight resistance in the eld. “Plants have got really good defence mechanisms, but for them to work, the plant has to knowwhen the pathogen appears, and once detected, activate its defence,” said Prof Jones. e molecules that enable the plant to detect the pathogen, called receptors, have the ability to be moved between plant species, where they continue to work. “Each resistance gene encodes a receptor that detects speci c molecules from the blight. Once detected, these receptors activate the potato’s defence mechanisms.” Another potato relative, Solanum americanum is not a host for the blight pathogen at all, so it is also being used as a source of resistance because its genes should make it very hard for the pathogen to adapt and break the resistance. “We need to use these methods to achieve the UN’s Sustainable Development Goals. GM role is key to achieving resilience Genetic modi cation could play a role in achieving better resilience in the potato sector, particularly through late blight resistance, said Prof Jonathan Jones of e Sainsbury Laboratory (TSL), Norwich. However, in Europe, for this to happen, current regulations need adjusting.” Silencing genes Prof Jones and his team have also been working with the US company Simplot, using Simplot’s technology to silence genes, including the invertase gene which cause enzymatic browning from mechanical damage such as bruising. Invertase is an enzyme that converts sucrose to a mixture of the reducing sugars glucose and fructose, he explained, adding that this has been an important move because these reducing sugars react with asparagine to make acrylamide at frying temperatures. “For example, lowering levels of invertase results in reduced levels of reducing sugars after cold storage, and therefore reduced acrylamide formation under high temperature cooking. Additionally, by silencing vacuolar invertase there is a further bene t because of reduced browning or blackening after high temperature cooking. is means that tubers can be stored longer at lower temperatures. With the current situation regarding the withdrawal of CIPC, this would be a very useful trait.” Simplot has brought this product to market in the US, as the quality traits and resistance genes were approved by the USDA and the FDA . To date, the only blight resistance gene deployed commercially is the Rpi-vnt1 gene cloned by Prof Jones and his team. (continued on page 41) “Plants have got really good defence mechanisms, but for them to work, the plant has to know when the pathogen appears, and once detected, activate its defence.”