Fusarium proliferatumcan infect many crops and then produce fumonisins that are very harmful to humans and animals. Previous study indicates that carbon sources play important roles in regulating the fumonisin biosynthesis. Unfortunately, there is limited information on the effects of carbon starvation in comparison with the carbon sources present in the host of fumonisin production inF. proliferatum. Our results indicated thatF. proliferatumcultivated in the Czapek’s broth (CB) medium in the absence of sucrose could greatly induce production of fumonisin, while an additional supplementation of sucrose to the culture medium significantly reduced the fumonisin production. Furthermore, cellulose and hemicellulose, and polysaccharide extracted from banana peel, which replaced sucrose as the carbon source, can reduce the production of fumonisin byF. proliferatum. Further work showed that these genes related to the synthesis of fumonisin, such asFUM1andFUM8, were significantly up-regulated in the culture medium in the absence of sucrose. Consistent with fumonisin production, the expressions ofFUMgene cluster andZFR1gene decreased after the addition of sucrose. Moreover, these genes were also significantly down-regulated in the presence of cellulose, hemicellulose or polysaccharide extracted from peel. Altogether, our results suggested that fumonisin production was regulated inF. proliferatumin response to different carbon source conditions, and this regulation might be mainly via the transcriptional level. Future work on these expressions of the fumonisin biosynthesis-related genes is needed to further clarify the response under different carbon conditions during the infection ofF. proliferatumon banana fruit hosts. The findings in this study will provide a new clue regarding the biological effect of the fumonisin production in response to environmental stress.Keywords:Fusarium proliferatum;fumonisin biosynthesis;carbon source;environmental stress;gene expressionKey Contribution:F. proliferatumcan produce fumonisins which are harmful to human health. This study aimed to explore the effect in the absence; followed by addition of carbon sources on fumonisin production; which will be beneficial for understanding the infection ofF. proliferatuminto banana fruit.
Li Taotao,Jian Qijie,Chen Feng,Wang Yong,Gong Liang,Duan Xuewu,Yang Bao,Jiang Yueming
Fusarium proliferatum as a common fungus pathogen in foods can produce toxic fumonisins, which can cause animal diseases and increase risks of human cancers. On contrary, butylated hydroxyanisole (BHA) as a synthetic antioxidant offers a clue for preventing growth of fungal species and inhibiting production of mycotoxins. Unfortunately, information of the inhibitory mechanism of BHA on Fusarium species is still limited. In this study, influence of BHA treatment on growth and inhibition of fumonisin production in relation to the expression of the fumonisin biosynthesis-related genes of the F. proliferatum ZYF was investigated, which revealed that BHA had a negative influence on growth and fumonisin production of F. proliferatum. To further elucidate the mechanism of BHA on the growth of F. proliferatum, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to examine the F. proliferatum hyphae. The BHA treatment induced the loss of cytoplasm and cellular constituents, as well as distortion of mycelia, but it did not directly degrade the fumonisin. Furthermore, the BHA treatment markedly inhibited the expressions of FUM1 (a polyketide synthase encoding gene) and FUM8 (an aminotransferase encoding gene) genes, which resulted in the depression of metabolic pathway of F. proliferatum. The transcriptional analyses of the FUM1 and FUM8 genes confirmed a correlation between the fumonisin production and its gene expression. This study provided some insights into mechanisms of production of fumonisin and feasible prevention to reduce fumonisin contamination in favor of human and animal health.
Fusarium proliferatum as a filamentous fungal pathogen can produce mycotoxins that can contaminate postharvest fruits and thus impact risks on human health. The extracellular proteomes of F . proliferatum grown in the absence and presence of butylated hydroxyanisole (BHA) were analyzed comparatively. A total of 66 significantly different expressed secreted proteins were identified by LC-ESI-MS/MS analysis. The BHA treatment suppressed the accumulation of some pathogenic factors such as aspartic protease , cell wall degradation enzymes , porin , superoxide dismutase and glyceraldehyde-3-phosphate dehydrogenase. On the contrary, the BHA treatment increased the abundances of some proteins, such as ATP binding cassette transporter substrate-binding protein and lipopolysaccharide-assembly lipoprotein , involved in the growth of F . proliferatum . These findings suggest that BHA treatment could influence the pathogenic ability of F . proliferatum via inhibiting the levels of virulence factors and cell wall degradation-associated enzymes . Moreover, the induction of the growth-related proteins after the BHA treatment suggests that the livelihood of F . proliferatum might depend on the cost of reduced pathogenic ability. This study has provided some evidence for understanding the complicated mechanisms of F . proliferatum infection in an effort to develop new targets for the control of this fungal pathogen. Biological significance To better understand the inhibitory mechanism of F . proliferatum by butylated hydroxyanisole (BHA) treatment, a comprehensive proteomic analysis of the secreted proteins of F . proliferatum was firstly conducted. Among the 66 identified spots, 34 and 32 proteins were down- and up-accumulated significantly by BHA treatment, respectively. Many of the identified key protein species were involved in the pathogenic ability and the growth of F . proliferatum . This study is helpful for broadening our knowledge of the pathogenic mechanism of F . proliferatum .
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