Aspergillus flavus SUMO Contributes to Fungal Virulence and Toxin Attributes

Abstract

Small ubiquitin-like modifiers (SUMOs) can be reversibly attached to target proteins in a process known as SUMOylation, and this process influences several important eukaryotic cell events. However, little is known regarding SUMO or SUMOylation in Aspergillus flavus. Here, we identified a novel member of the SUMO family in A. flavus, AfSumO, and validated the existence of SUMOylation in this pathogenic filamentous fungus. We investigated the roles of AfsumO in A. flavus by determining the effects of AfsumO mutations on the growth phenotype, stress response, conidia and sclerotia production, aflatoxin biosynthesis, and pathogenicity to seeds, and we found that SUMOylation plays a role in fungal virulence and toxin attributes. Taken together, these results not only reveal potential mechanisms of fungal virulence and toxin attributes in A. flavus but also provide a novel approach for promising new control strategies of this fungal pathogen.

SUMOylation is required for fungal development and pathogenicity in the rice blast fungus Magnaporthe oryzae

“…Like the other mutants of SUMOylation components in other organisms (Gujjula et al ., ; Leach et al ., ; Nie et al ., ; Wong et al ., ), Δ Mosmt3 , Δ Moaos1 , Δ Mouba2 , Δ Moaos1 Δ Mouba2 and Δ Moubc9 showed significantly reduced mycelial growth, conidiation, conidial germination, appressorium formation, stress resistance and pathogenicity. Deletion of the SUMOylation‐associated genes was not lethal, unlike in S. cerevisiae and C. glabrata (Gujjula et al ., ; Schwarz et al ., ), but deletion of even one of these genes almost abolished SUMOylation in M. oryzae .…”

“…Subsequent identification of SUMOylated motifs in conidiation‐related genes further supports the hypothesis that the modification of conidiation‐related genes by SUMO controls conidiation in M. oryzae . Similar conidiation phenotypes were reported in SUMOylation mutants of A. nidulans and A. flavus (Nie et al ., ; Wong et al ., ). These results suggest that SUMOylation is crucial for conidiation in filamentous fungi.…”

“…Amongst the SUMOylation components, SMT3, AOS1, UBA2, UBC9, MMS21 and ULP1 are essential for viability (Johnson and Blobel, 1999). However, in other fungal species, such as Schizosaccharomyces pombe, Aspergillus nidulans, A flavus and Candida albicans, SUMO is not essential for viability (Leach et al, 2011;Nie et al, 2016;Tanaka et al, 1999;Wong et al, 2008). Despite these functional studies, the functional roles of the SUMOylation pathway in plant-pathogenic fungi are unclear.…”

Lysine acetylation contributes to development, aflatoxin biosynthesis and pathogenicity in Aspergillus flavus

“…In A. flavus , Lan found that histone acetyltransferase and deacetylase play important roles in the production of aflatoxin by regulating modifications of histone acetylation (Lan et al ., ; Lan et al ., ). In addition, the results of acetylation‐mediated aflatoxin biosynthesis agree with the results of other reported PTMs in A. flavus , including phosphorylation (Ren et al ., ), SUMOylation (Nie et al ., ) and succinylation (Ren et al ., ). Taken together, we conclude that lysine acetylation is critical for secondary metabolism in A. flavus .…”

“…And then, an electron microscope (Leica, Wetzlar, Germany) was used to observe the morphology of conidiophores. For sclerotial production assay, each strain was spotted onto WKM agar medium and grown at 37°C for corresponding days in darkness (Nie et al ., ). Then, the plates were sprayed with 75% ethanol to wash mycelial and conidia so as to expose sclerotial.…”