2 May 2013 Biosecurity tools for plant virus detection

Plant viruses are notoriously difficult to detect and present a significant economic risk to New Zealand’s productive industries. 

However, an innovative research project by Anastasija Chomic a PhD student at the Bio-Protection Research Centre, has resulted in the development of molecular tools that could help to keep new viruses out of the country. Ana’s PhD project focused on developing a faster and more sensitive detection method for members of the Luteoviridae virus family.

Luteoviridae viruses attack economically important crops such as cereals, potatoes and legumes. They are spread by aphids which move between plants, so by the time symptoms such as discolouration, leaf spots or stunted growth become apparent, other parts of the affected plant, neighbouring plants and even neighbouring paddocks are also likely to be infected. Thus, early detection is the key to preventing spread.

Traditionally virus detection has relied on a relatively insensitive, slow and species-specific antibody-based ELISA test. More recent polymeran chain reaction (PCR) methods enable very small DNA samples to be tested by amplifying the segment to sufficient quantities to be studied. Methods are faster and more sensitive, but are still species specific and, because of the fast mutation rate of virus genomes, can produce false negatives.

Ana’s first step was to develop a generic PCR test capable of detecting 13 out of 26 species ofLuteoviridae. She then progressed her method with the innovative use of a new technique, melt curve analysis (MCA). MCA overcomes the need for expensive high tech sequencing equipment, shortens assay time and reliably distinguishes six species of Luteoviridae from each other, and from other groups.

Importantly Ana proved that MCA is sensitive enough to detect asymptomatic infection, as well as double infection. The tests, or assays, that Ana developed were evaluated in plant hosts only, but could be also extended for detection of the Luteoviridae in their vectors – aphids. The assays require full validation before they can be used for diagnostics, however Ana is confident that they could save regulatory agencies time and money in a number of areas from routine biosecurity virus screening surveys, to assessing virus resistance traits in plant breeding.

For more information, read the full article on page 80 of the University’s research profile publication Transform.