indicate that treatments with B. subtilis IAB/BS03 significantly
reduced both the incidence and severity of
lettuce downy mildew compared with the untreated
plants. This efficacy was comparable to that of a commercially
available, synthetic fungicide.
These results demonstrate that B. subtilis IAB/BS03
application provides protection against different diseases
on different crops, and in many cases is as efficacious
as synthetic pesticides. B. subtilis IAB/BS03 is
registered and has been patented (US2014/
0,314,718 A1 and PCT/ES2012/070,310), adding it to
the list of commercially available B. subtilis products
(Choudhary and Johri 2009).
Treatments with B. subtilis IAB/BS03 produced an
up-regulation of antifungal protein PR1 in tomato plant
leaves. Similar results have been reported for
Arabidopsis plants after root inoculation with two
B. subtilis strains (Rudrappa et al. 2010; Niu et al.
2011). We detected neither peroxidase gene induction
nor increased peroxidase enzyme activity. This is in
agreement with previous results describing ISR by
PGPR not requiring substantial transcriptome
reprogramming since gene expression changes are usually
weak or undetectable (Verhagen et al. 2004). In
contrast, ISR is characterised by the establishment of a
primed defence state in which further defence-related