TY - JOUR
T1 - Aspergillus flavus exploits maize kernels using an “orphan” secondary metabolite cluster
AU - Antiga, Ludovica
AU - La Starza, Sonia Roberta
AU - Miccoli, Cecilia
AU - D’angeli, Simone
AU - Scala, Valeria
AU - Zaccaria, Marco
AU - Shu, Xiaomei
AU - Obrian, Gregory
AU - Beccaccioli, Marzia
AU - Payne, Gary A.
AU - Reverberi, Massimo
N1 - Publisher Copyright:
© 2020 by the authors. Licensee MDPI, Basel, Switzerland.
PY - 2020/11/1
Y1 - 2020/11/1
N2 - Aspergillus flavus is a saprophytic cosmopolitan fungus, capable of infecting crops both pre-and post-harvest and exploiting different secondary metabolites, including aflatoxins. Aflatoxins are known carcinogens to animals and humans, but display no clear effect in host plants such as maize. In a previous study, we mined the genome of A. flavus to identify secondary metabolite clusters putatively involving the pathogenesis process in maize. We now focus on cluster 32, encoding for fungal effectors such as salicylate hydroxylase (SalOH), and necrosis-and ethylene-inducing proteins (npp1 domain protein) whose expression is triggered upon kernel contact. In order to understand the role of this genetic cluster in maize kernel infection, mutants of A. flavus, impaired or enhanced in specific functions (e.g., cluster 32 overexpression), were studied for their ability to cause disease. Within this frame, we conducted histological and histochemical experiments to verify the expression of specific genes within the cluster (e.g., SalOH, npp1), the production of salicylate, and the presence of its dehydroxylated form. Results suggest that the initial phase of fungal infection (2 days) of the living tissues of maize kernels (e.g., aleuron) coincides with a significant increase of fungal effectors such as SalOH and Npp1 that appear to be instrumental in eluding host defences and colonising the starch-enriched tissues, and therefore suggest a role of cluster 32 to the onset of infection.
AB - Aspergillus flavus is a saprophytic cosmopolitan fungus, capable of infecting crops both pre-and post-harvest and exploiting different secondary metabolites, including aflatoxins. Aflatoxins are known carcinogens to animals and humans, but display no clear effect in host plants such as maize. In a previous study, we mined the genome of A. flavus to identify secondary metabolite clusters putatively involving the pathogenesis process in maize. We now focus on cluster 32, encoding for fungal effectors such as salicylate hydroxylase (SalOH), and necrosis-and ethylene-inducing proteins (npp1 domain protein) whose expression is triggered upon kernel contact. In order to understand the role of this genetic cluster in maize kernel infection, mutants of A. flavus, impaired or enhanced in specific functions (e.g., cluster 32 overexpression), were studied for their ability to cause disease. Within this frame, we conducted histological and histochemical experiments to verify the expression of specific genes within the cluster (e.g., SalOH, npp1), the production of salicylate, and the presence of its dehydroxylated form. Results suggest that the initial phase of fungal infection (2 days) of the living tissues of maize kernels (e.g., aleuron) coincides with a significant increase of fungal effectors such as SalOH and Npp1 that appear to be instrumental in eluding host defences and colonising the starch-enriched tissues, and therefore suggest a role of cluster 32 to the onset of infection.
KW - Aspergillus flavus
KW - Effectors
KW - Histology
KW - Maize kernel
KW - Npp1
KW - Quercetin
KW - Salicylate hydroxylase
UR - http://www.scopus.com/inward/record.url?scp=85095783440&partnerID=8YFLogxK
U2 - 10.3390/ijms21218213
DO - 10.3390/ijms21218213
M3 - Article
C2 - 33153018
AN - SCOPUS:85095783440
SN - 1661-6596
VL - 21
SP - 1
EP - 17
JO - International journal of molecular sciences
JF - International journal of molecular sciences
IS - 21
M1 - 8213
ER -