Biomedical Science and Research Journals | Assessment of 3 Tac-I/Beta, an Antimicrobial Peptide Source, in the Control of Pseudomonas Plant Pathogens
Diseases caused by Pseudomonas syringae and other species of Pseudomonas
cause severe losses in different fruit crops worldwide. Antimicrobial
peptides (AMPs) are small and consist of a variety of proteins that act
on the lipid bilayer of the bacterial membrane that is produced by
multicellular
organisms. The product, 3 Tac-I/Beta, is a biopesticide that bases its
action on three Trichoderma strains (T. viride strain T-26, T. harzianum strain
T-22, and T. longibrachiatum strain T-397), its total concentration is >25 x 103 c.f.u. g-1,
which is authorized in Chile to control different fungal diseases
in fruit and vegetable crops. However, the reduction of bacterial stone
canker disease has suggested a possible AMPs mode of action associated
with
3 Tac-I/Beta. In this study we used Transmission Electronic Microscopy
(TEM) to assess the possible AMP activity of this product on the
bacterial
membrane of Pseudomonas syringae pv. syringae (Pss). The effect of two filtered solutions of 3 Tac-I/Beta (commercial and concentrated) on the
population of this bacterium was assessed by using in vitro tests.
Control on this bacterial plant pathogen in cherry plants cv. Bing
treated with 3 Tac-I/Beta, copper hydroxide, and copper oxide was
assessed
in a pot experiment. This TEM study showed a marked damage on the
membrane of P. syringae pv. syringae, which affected the bacillus shape of
the bacterium by changing the continuity of its membrane. In vitro
tests on a homogeneous lawn of Pss showed the formation of inhibition
halos
around discs treated with filtered 3 Tac-I/Beta across the surface of
agar King B-medium plates. Reduction in the bacterial population after
18 hours
of bacterial growth in King B medium amendment with a solution of
commercial and concentrated filtered of 3 Tac-I/Beta were observed.
Bacterial
growth, expressed as the optical density of cell culture, was reduced by
around 12% when 3 Tac-I/Beta was used, while a concentrated AMP
solution
of filtered 3 Tac-I/Beta showed a reduction of around 34.8% after 18
hours of co-culture. The effect on bacterial growth was maintained for
30 hours
for both filtered solutions of the product. Preventive spraying of 3
Tac-I/Beta on cherry plants cv. ‘Bing’.
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