TRV infection causes spraing production in tubers of susceptible potato cultivars

Tobacco rattle virus (TRV) and spraing production

The plant virus Tobacco rattle virus (TRV) occurs in many different countries throughout the world including the UK and is able to infect more than 400 plant species. In crop plants TRV causes important diseases of potato, ornamental plants (gladiolus, narcissus, tulip, aster and other species), sugar beet and tobacco. Many common weed species, such as Common Chickweed (Stellaria media) and Shepherd’s Purse (Capsella bursa-pastoris), are hosts of TRV and act as a reservoir of the virus in the field. TRV is spread from plant to plant by root-feeding trichodorid nematodes (Trichodorus spp. and Paratrichodorus spp.), and in some plant species is also spread by infected seeds.

Potato plants become infected with TRV from nematodes in the soil that feed on the developing tubers. Using seed potatoes that are already infected with TRV will further spread the virus into the growing crop. It is currently thought that there are three types of response to TRV by different potato cultivars. Some cultivars, such as Bintje, are immune to TRV infection, although isolates of TRV have arisen that can overcome this resistance. A second group of cultivars, such as Nadine, are completely susceptible to TRV, so that the virus spreads throughout the infected plant causing little or no observable symptoms. However, work at the James Hutton Institute has shown that after several generations such potato plants produce smaller and more irregular tubers. The third group of cultivars, such as Pentland Dell, react to TRV infection by producing arcs of discolouration (known as spraing) inside the tubers, as well as surface lesions and malformations. Potato crops with spraing symptoms can be rejected for sale.

microarray data of spraing

We have examined the biochemical and genetic basis of spraing production following TRV infection. We used micro-array analysis to examine which potato genes are up- or down-regulated during spraing production, providing us with information about the biochemical processes involved in spraing formation. We combined this work with a quantitative study of TRV infection in potato tubers, with the aim of understanding how and why TRV triggers spraing production. The results of this study are published in the scientific journal Molecular Plant-Microbe Interactions (Sahi, G., Hedley, P.E., Morris, J., Loake, G.J. and MacFarlane, S.A. 2016. Molecular and biochemical examination of spraing disease in potato tuber in response to Tobacco rattle virus infection. Molecular Plant-Microbe Interactions, 29, 822-828).