Climate change-induced drought triggers a reproductive phase shift in Aspergillus flavus, increasing Aflatoxin B1 contamination in lima beans
Abstract
Climate change is anticipated to increase the frequency and intensity of droughts in Sub-Saharan Africa, posing significant risks to legume production and food safety. Lima bean ( Phaseolus lunatus ), a staple crop and source of income in the Central African Republic, is susceptible to infection by Aspergillus flavus , which produces aflatoxin B 1 . Using complementary in situ and in vitro experiments, we investigated how drought affects plant sensitivity, fungal development, and toxin accumulation. Drought stress significantly altered the reproductive behavior of A. flavus and increased aflatoxin B 1 production. This reproductive phase shift contrasts with previously described drought-toxigenesis patterns and reveals how environmental stress can reshape fungal developmental plasticity. Furthermore, we observed that severe drought reduced biomass and SPAD values (an indirect proxy for chlorophyll content), while necrotic leaf area increased sharply under high fungal pressure. These responses indicate that drought weakens plant defenses and enhances susceptibility to fungal colonization. This more aggressive colonization was associated with elevated aflatoxin B 1 levels in leaves under extreme drought, demonstrating a marked increase in toxigenic activity. In vitro , osmotic stress caused by polyethylene glycol (PEG) induced significant morphological changes in A. flavus, including the abundant formation of Hülle cells and cleistothecia, sexual structures that are rarely seen in A. flavus i n agricultural contexts. Aflatoxin B 1 concentrations peaked during these reproductive shifts, indicating coordinated stress-induced mechanisms that promote survival and toxigenesis. Overall, our findings show that drought increased host susceptibility and aflatoxin accumulation, acting as a dual risk factor for both infection and toxigenesis. • Severe drought amplifies Aspergillus flavus spread and aflatoxin B 1 contamination in lima bean. • Polyethylene glycol-induced water stress promotes Hülle cell formation and cleistothecia in A. flavus . • A shift to sexual reproduction during drought coincides with peak levels of aflatoxin B 1 . • In planta aflatoxin B 1 exceeds safety thresholds in drought-stressed, contaminated plants. • Climate change functions as a “susceptibility amplifier” for fungal toxin outbreaks.
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BibTeX
@article{agboko2026climate,
title = {{Climate change-induced drought triggers a reproductive phase shift in Aspergillus flavus, increasing Aflatoxin B1 contamination in lima beans}},
author = {Freddy Marcelin Agboko and Rajbir Sangwan and Lamine Bensaddek and Silla Semballa and Jérôme Duclercq},
journal = {Physiological and Molecular Plant Pathology},
year = {2026},
month = sep,
doi = {10.1016/j.pmpp.2025.103106},
url = {https://u-picardie.hal.science/hal-05735602v1},
note = {CC BY},
}
RIS
TY - JOUR
TI - Climate change-induced drought triggers a reproductive phase shift in Aspergillus flavus, increasing Aflatoxin B1 contamination in lima beans
AU - Freddy Marcelin Agboko
AU - Rajbir Sangwan
AU - Lamine Bensaddek
AU - Silla Semballa
AU - Jérôme Duclercq
PY - 2026
DA - 2026/09/02
JO - Physiological and Molecular Plant Pathology
DO - 10.1016/j.pmpp.2025.103106
UR - https://u-picardie.hal.science/hal-05735602v1
AB - Climate change is anticipated to increase the frequency and intensity of droughts in Sub-Saharan Africa, posing significant risks to legume production and food safety. Lima bean ( Phaseolus lunatus ), a staple crop and source of income in the Central African Republic, is susceptible to infection by Aspergillus flavus , which produces aflatoxin B 1 . Using complementary in situ and in vitro experiments, we investigated how drought affects plant sensitivity, fungal development, and toxin accumulation. Drought stress significantly altered the reproductive behavior of A. flavus and increased aflatoxin B 1 production. This reproductive phase shift contrasts with previously described drought-toxigenesis patterns and reveals how environmental stress can reshape fungal developmental plasticity. Furthermore, we observed that severe drought reduced biomass and SPAD values (an indirect proxy for chlorophyll content), while necrotic leaf area increased sharply under high fungal pressure. These responses indicate that drought weakens plant defenses and enhances susceptibility to fungal colonization. This more aggressive colonization was associated with elevated aflatoxin B 1 levels in leaves under extreme drought, demonstrating a marked increase in toxigenic activity. In vitro , osmotic stress caused by polyethylene glycol (PEG) induced significant morphological changes in A. flavus, including the abundant formation of Hülle cells and cleistothecia, sexual structures that are rarely seen in A. flavus i n agricultural contexts. Aflatoxin B 1 concentrations peaked during these reproductive shifts, indicating coordinated stress-induced mechanisms that promote survival and toxigenesis. Overall, our findings show that drought increased host susceptibility and aflatoxin accumulation, acting as a dual risk factor for both infection and toxigenesis. • Severe drought amplifies Aspergillus flavus spread and aflatoxin B 1 contamination in lima bean. • Polyethylene glycol-induced water stress promotes Hülle cell formation and cleistothecia in A. flavus . • A shift to sexual reproduction during drought coincides with peak levels of aflatoxin B 1 . • In planta aflatoxin B 1 exceeds safety thresholds in drought-stressed, contaminated plants. • Climate change functions as a “susceptibility amplifier” for fungal toxin outbreaks.
SN - 0885-5765
SN - 1096-1178
ER -