Part J - Epidemiology and Diagnostics Flashcards
Why are molecular assays advantageous in the diagnostics of plant diseases? Give one example of a molecular method and explain how it works.
They are more sensitive and specific than traditional methods.
One example of a molecular method is a polymerase chain reaction (PCR) test.
PCR is a technique that makes many copies of a specific DNA sequence. This allows for the identification and quantification of pathogens even if they are present in very low numbers.
A real-time PCR test is almost always a better option though as it does not require post-PCR processing and is much more robust.
Why are plant diseases a problem in most agricultural production systems but not so much in natural ecosystems?
This is because of the bunching up of plants per hectare.
Monoculture leads to a much higher density and thus transmission of pathogens is much easier as they do not have to travel far and some are favourable due to their short lifespan outside of their host.
Pesticide use also adds to the issue as they could sometimes inhibit beneficial insects that would feed on specific pathogens, decreasing predation and increasing infection rate.
While in natural ecosystems, plants are much more diverse, natural enemies are allowed to coexist and higher genetic diversity contributes to lower infection rates than in agricultural monoculture.
What practical advantage does the use of Loop-mediated amplication (LAMP) oer over PCR based plant pathogen diagnostics?
Ease of use: LAMP assays are relatively easy to set up and run, requiring fewer reagents and steps than PCR.
Speed: LAMP assays can be completed in as little as 1 hour, compared to 2-4 hours for PCR.
Sensitivity: LAMP assays can detect very low levels of target DNA, making them ideal for early detection of plant pathogens.
Specificity: LAMP assays are highly specific, meaning that they are unlikely to produce false positives.
Cost-effectiveness: LAMP assays are relatively inexpensive to perform, making them a cost-effective option for plant pathogen diagnostics.
