Interpreting Relationships between the Concentrations of Plant Viruses and Numbers of Local Lesions

Abstract

In an analysis of the mechanism of virus infection it was shown that the numbers of lesions produced by the tobacco viruses investigated fit the hypothesis that susceptible regions vary in susceptibility, and that the minimum doses necessary to initiate local infections vary in such a way that their logarithms are normally distributed. This contrasts with the results of Lauffer and Price, (1945), whose interpretation is criticized and who concluded that susceptible regions are uniformally susceptible; this hypothesis can only be established by the introduction of auxilliary assumptions. The paper is also useful as a statistical model, giving examples of suitable exptl. designs and of curve fitting to the Poisson series and to the equation: [image] with the accompanying regression analysis and estimation of variance. In the equation, Y = expected no. of lesions per half-leaf, N is the mean no. of the susceptible regions'' per half-leaf, t = logl10 x (x = virus concn. in the inoculum or dilution of infective sap), [xi] = log10 X 0 (x 0 = virus concn. or dilution of infective sap when 50% of the susceptible regions develop lesions), and [lambda] is the standard deviation.