To determine whether P. oligandrum induced resistance against
black scurf caused by R. solani in potato, tuber disks treated with
CWP, P. oligandrum oospore suspension (OS), or DW were
challenged with R. solani 6 h after treatment. Disease severity
7 days after inoculation was significantly reduced by 80.7% and
91.7% on the treatments with CWP and OS, respectively, when
compared with the DW control (Fig. 5). This result suggests that
the disease suppression by CWP treatment was involved in
induced resistance, although the disease suppression by OS
treatment was also involved in mycoparasitism. Therefore, expression
of defense-related genes such as DAHPS, LOX-E, and PR-6 in
CWP-treated tuber disks was compared with DW-treated tuber
disks by northern blot analysis. Representative northern blot from
one of the three independent experiments is shown in Fig. 6