described
The mean percentage of A. citrulli-positive seed sections was
determined for each seed lot. To confirm real-time PCR assay
results, attempts were made to isolate A. citrulli from seed sections.
Samples (n = 20 seeds/lot) were dissected into testa, PE
layer and embryo tissues as described above and the tissues were
macerated separately in PBS and 100-μl aliquots were spread onto
Nunhems semiselective medium. Plates were incubated for 5 days
at 28°C and the percentage of A. citrulli-positive seed sections
was compared for seeds inoculated by each method. For statistical
analysis the mean percentage of A. citrulli-positive seed tissues
for each lot (as determined by real-time PCR assay and plating on
semiselective media) were compared by factorial analysis using
the Student’s t test (P < 0.05) in SAS (version 8.1 for Windows;
SAS Institute Inc., Cary, NC).