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BMC Plant Biology
Springer Nature
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Abstract: |
Wheat is one of the essential crops for the human and animal nutrition, however, contamination with aflatoxigenic
fungi, due to the improper storage conditions and high humidity, was the main global threats. So, preventing
the growth of aflatoxigenic fungi in stored wheat grains, by using different essential oils was the main objective of this
work. Aspergillus flavus EFBL-MU12 PP087400, EFBL-MU23 PP087401 and EFBL-MU36 PP087403 isolates were the most
potent aflatoxins producers inhabiting wheat grains. The effect of storage conditions of wheat grains “humidity, temperature,
incubation period, and pH” on growth of A. flavus, was assessed by the response surface methodology using
Plackett-Burman design and FCCD. The highest yield of aflatoxins EFBL-MU12 B1
and B2
by A. flavus grown on wheat
grains were 145.3 and 7.6 μg/kg, respectively, at incubation temperature 35°C, 16% moisture contents, initial pH 5.0,
and incubated for 14 days. The tested oils had a powerful antifungal activity for the growth and aflatoxins production
by A. flavus in a concentration-dependent manner. Among these oils, cinnamon oil had the highest fungicidal activity
for A. flavus at 0.125%, with about 85-90 % reduction to the aflatoxins B1
and B2,
conidial pigmentation and chitin
contents on wheat grains. From the SEM analysis, cinnamon oils had the most deleterious effect on A. flavus with morphological
aberrations to the conidial heads, vegetative mycelia, alteration in conidiophores identity, hyphae shrank,
and winding. To emphasize the effect of the essential oils on the aflatoxins producing potency of A. flavus, the molecular
expression of the aflatoxins biosynthetic genes was estimated by RT-qPCR. The molecular expression of nor-1,
afLR, pKsA and afLJ genes was suppressed by 94-96%, due to cinnamon oil at 0.062% compared to the control.
Conclusively, from the results, cinnamon oils followed by the peppermint oils displayed the most fungicidal activity
for the growth and aflatoxins production by A. flavus grown on wheat grains
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