Multiple regression analysis of the relationships between tobacco mosaic virus multiplication, the severity of mosaic symptoms, and the growth of tobacco and tomato

Abstract

This paper deals with quantitative aspects of the control of growth of virus-infected plants. Tobacco and tomato plants were inoculated with a total of 26 different strains of tobacco mosaic virus. These multiplied to varying extents, and caused mosaic symptoms of varying severity. Virus multiplication, plant growth and severity of mosaic symptoms were measured. Multiple regression analysis showed that variation in virus multiplication and symptom severity could account for most of the variation in growth which occurred as a result ofinfection. In tomato, variation in symptom severity was the dominant factor, and variation in virus multiplication could account for negligible amounts of variation in growth. In tobacco, variation in symptom severity and in virus multiplication could account for approximately equal amounts of variation in growth. The implied importance of amount of virus multiplication in control of growth of infected tobacco, but not of tomato, might reflect the finding that the virus multiplied to higher concentrations overall in tobacco than in tomato. Possible mechanisms linking mosaic symptom severity and inhibition of growth are discussed: it is suggested that in tobacco, but not tomato, alterations in the metabolism and localization of abscisic acid may be important.