Tech talk: bright device picks up GM fruit contaminates
By Lumora senior molecular biologist and digital amplification team leader Dr Guy Kiddle
The production and commercialization of of genetically modified (GM) crops is still a relatively new technology that was adopted to introduce beneficial traits (genes) into wild-type plants, to improve the yield and quality of a given crop. Many of the plants that contain these modified genomes overexpress trans-genes conferring disease and herbicide resistance. Commercial varieties of banana plants, apples and papaya fruits are all available with various resistance genes. This new agricultural practice is particularly important, where traditional methods of plant breeding are not an option; for example if a plant is under threat from a pathogen, but it is derived from one ancestral germ-line.
GM technology has also been used to develop varieties of fruit with improved qualities. For example, grapes have now been engineered that can grow larger and more rapidly than the wild-type cultivars; other grape genomes have been altered to produce modified compositions of sugars, in an attempt to improve the quality of fruits for the wine-growing industry. Many other genes have been introduced into fruit plants, which improve their shelf life, flavor, appearance and even the vitamin and antioxidant contents.
Despite the obvious benefits provided by this molecular manipulation, there are still concerns and fear surrounding this agricultural evolution and the distribution of transformed plants is still largely confined to the Americas, where the regulation of this technology is not as stringent. In 40 countries including Europe, China and Japan, consumers demand the ‘right to know’ whether the food they are consuming has been genetically modified. The state of California now appears to be following suit demanding more transparency from food producers to label products; the consumers will have a chance to vote on this sensitive issue later in the year. These recent advances in food production and regulation have compelled the diagnostics industry to develop new methods of monitoring the distribution of genetically modified (GM) plant products within the field environment and throughout the food chain.
The most efficient way to measure measure GM contamination is to look for the associated DNA, which can be detected in very small quantities by molecular amplification techniques. Normally, this type of analysis requires costly equipment, laboratories and highly trained personnel. Alternative techniques have now been developed by Lumora, which are rapid, easy-to-use, robust and sensitive. Moreover, due to the simplistic sample preparation, molecular amplification and detection can be deployed within field environments, by non-expert users. The success of these new assays can largely be attributed to the displacement DNA polymerase at the heart of each assay. This enzyme is more tolerant of plant derived inhibitors, known to inhibit conventional molecular amplifications. Coupled to the new amplification method is a bioluminescent reporter (BART) that detects the contaminating target DNA, as a flash of light, which is easy to monitor with robust, low-cost hardware.
As well as GM, fruit is well known to contain large concentrations of the problematic sugars; Lumora’s sample preparation therefore lends itself well to monitoring the genetic authenticity of fruit. Moreover, the technology described, is very versatile and can be tuned to measure other genes, which affect the fruit growing industry, such as those that denote food spoilage agents. A. acidoterrestris (TAB) is considered to be one of the main challenges to be overcome by the fruit juicing industry. It is nearly impossible to guarantee the absence of this microorganism and its spores are very persistent in orchard soils, in fruits and within the food chain. Moreover the pasteurisation process designed to eradicate spoilage agents, has little effect on this microorganism. Current tests involve enrichment of this organism before analysis can commence. It is conceivable that Lumora’s diagnostic analysis could also be used to monitor these food spoilage agents from the fruit orchards and throughout the food processing chain.