Effects of tuber-borne M-type strain of tobacco rattle virus on yield and quality attributes of potato tubers of the cultivar Wilja

It was previously thought that Tobacco Rattle Virus (TRV) was self-eliminat ing from seed potato stocks and that the principal effects of the virus wer e the spraing symptoms (arcs or lines of corky brown tissue) formed in the tuber flesh. Recent work has clearly demonstrated that the virus can become fully and systemically established in some potato cultivars, with few, if any, tuber flesh symptoms. The studies reported here demonstrate that, in a t least one such cultivar, an M-type strain of the virus can have a conside rable effect on the growth and quality of the plant and its produce. When i nfected material was compared with healthy material, overall yield and yiel d components were severely affected by TRV, as were quality traits such as dry matter, after-cooking blackening and chemical components such as sugars , glycoalkaloids and chlorogenic acid. The results are discussed in terms o f plant response to virus infection and plant protection mechanisms.