Comparison of two different carrot <i>A. dauci</i> colonization evaluation methods, symptom number assessment and qPCR-based fungal biomass evaluation.

<p>Carrot plants of six different genotypes were tested for <i>Alternaria dauci</i> resistance using two different methods simultaneously. Plants were grown in greenhouse conditions. The third leaf was inoculated after it was isolated in an incubation chamber without detaching it from the plant. The symptom number was assessed at 7, 9 and 13 dpi. At 13 dpi, leaves were detached and then subjected to DNA extraction and qPCR for fungal biomass evaluation. Log(AUDPC) was calculated from the visual assessments, log(I+1) from the qPCR experiments. Both were subjected to variance analysis followed by a Waller-Duncan multiple comparison. As could be expected, the two parameters were closely correlated (r² = 0.793). Interestingly, log(AUDPC) seemed to show a higher resolution, as the homogeneity groups appeared to be more numerous (4 vs 2).</p>1<p>Homogeneity goups were calculated using the Waller-Duncan multiple comparison following an ANOVA analysis.