SCIENTIFIC RePORts | (2018) 8:3430 | DOI:10.1038/s41598-018-21653-x
Proteome analysis of Aspergillus
avus isolate-specic responses to
oxidative stress in relationship to
aatoxin production capability
Jake C. Fountain
, Jin Koh
, Liming Yang
, Manish K. Pandey
, Spurthi N. Nayak
, Wei-Jian Zhuang
, Zhi-Yuan Chen
, Robert C. Kemerait
, R. Dewey Lee
, Rajeev K. Varshney
& Baozhu Guo
Aspergillus avus is an opportunistic pathogen of plants such as maize and peanut under conducive
conditions such as drought stress resulting in signicant aatoxin production. Drought-associated
oxidative stress also exacerbates aatoxin production by A. avus. The objectives of this study were to
use proteomics to provide insights into the pathogen responses to H
-derived oxidative stress, and to
identify potential biomarkers and targets for host resistance breeding. Three isolates, AF13, NRRL3357,
and K54A with high, moderate, and no aatoxin production, were cultured in medium supplemented
with varying levels of H
, and examined using an iTRAQ (Isobaric Tags for Relative and Absolute
Quantication) approach. Overall, 1,173 proteins were identied and 220 were dierentially expressed
(DEPs). Observed DEPs encompassed metabolic pathways including antioxidants, carbohydrates,
pathogenicity, and secondary metabolism. Increased lytic enzyme, secondary metabolite, and
developmental pathway expression in AF13 was correlated with oxidative stress tolerance, likely
assisting in plant infection and microbial competition. Elevated expression of energy and cellular
component production in NRRL3357 and K54A implies a focus on oxidative damage remediation.
These trends explain isolate-to-isolate variation in oxidative stress tolerance and provide insights into
mechanisms relevant to host plant interactions under drought stress allowing for more targeted eorts
in host resistance research.
Aspergillus avus (Link ex Fr, Teleomorph: Petromyces avus) is a facultative plant pathogen, which is capable of
infecting maize and peanut. e infection of these crops by A. avus poses a serious threat to human and animal
health due to its production of carcinogenic mycotoxins, termed as aatoxins, resulting in contamination of food-
stus and livestock feed
. Aatoxin contamination also leads to signicant economic losses globally due to lost
crop value and regulatory restrictions on import and export of contaminated materials
Research eorts have been focused on prevention of both pre-and post-harvest aatoxin contamination
Pre-harvest aatoxin contamination is managed mainly through host genetic resistance, irrigation, insect con-
trol, and the application of atoxigenic biological control isolates of A. avus, such as Aaguard (NRRL21882)
and AF36 (NRRL18543) which compete with toxigenic isolates for available niches in the environment
Host resistance to A. avus colonization and aatoxin contamination is highly quantitative rather than specic
. is resistance is also highly inuenced by abiotic stresses such as drought and heat
Department of Plant Pathology, University of Georgia, Tifton, GA, USA.
USDA-ARS Crop Protection and
Management Research Unit, Tifton, GA, USA.
Center of Excellence in Genomics & Systems Biology, International
Crop Research Institute for the Semi-Arid Tropics (ICRISAT), Patancheru, Telangana, India.
Department of Biology,
Genetics Institute, Interdisciplinary Center for Biotechnology Research, University of Florida, Gainesville, FL, USA.
College of Biology and Environmental Science, Nanjing Forestry University, Nanjing, China.
College of Plant
Protection, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China.
Department of Plant Pathology
and Crop Physiology, Louisiana State University, Baton Rouge, LA, USA.
Department of Crop and Soil Sciences,
University of Georgia, Tifton, GA, USA. Correspondence and requests for materials should be addressed to B.G.
Received: 6 October 2017
Accepted: 3 February 2018
Published: xx xx xxxx