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Aldehyde dehydrogenase (ALDH), a common oxidoreductase in organisms, is an aldehyde scavenger involved in various metabolic processes. However, its function in different pathogenic fungi remains unknown. Fusarium graminearum causes Fusarium head blight in cereals, which reduces grain yield and quality and is an important global food security problem. To elucidate the pathogenic mechanism of F. graminearum, seven genes encoding ALDH were knocked out and then studied for their function. Single deletions of seven ALDH genes caused a decrease in spore production and weakened the pathogenicity. Furthermore, these deletions altered susceptibility to various abiotic stresses. FGSG_04194 is associated with a number of functions, including mycelial growth and development, stress sensitivity, pathogenicity, toxin production, and energy metabolism. FGSG_00139 and FGSG_11482 are involved in sporulation, pathogenicity, and SDH activity, while the other five genes are multifunctional. Notably, we found that FGSG_04194 has an inhibitory impact on ALDH activity, whereas FGSG_00979 has a positive impact. RNA sequencing and subcellular location analysis revealed that FGSG_04194 is responsible for biological process regulation, including glucose and lipid metabolism. Our results suggest that ALDH contributes to growth, stress responses, pathogenicity, deoxynivalenol synthesis, and mitochondrial energy metabolism in F. graminearum. Finally, ALDH presents a potential target and theoretical basis for fungicide development.

The prevention of fungal spoilage is an essential consideration in wheat storage. Recent studies have revealed that volatile organic compounds (VOCs), possibly with natural fungicidal properties, could be produced from stored wheat grains. In this study, the antifungal effect of hexanal, a main component of VOCs from stored wheat, against spoilage fungi on agar plate and in high-moisture wheat grains were investigated via the gas fumigation method. And the impact of hexanal fumigation on grain quality was evaluated through analysis of the malondialdehyde content, fatty acid values, germination percentages and vigor of 16% and 18% moisture wheat grains fumigated with 1.66, 2.49, and 3.31 mmol/L hexanal vapor. The results of in vitro antifungal experiments on agar plates revealed that the minimum inhibitory concentration and minimum fungicidal (fatal) concentration of hexanal against the five fungi were 4–14 folds and 4–7 folds lower than those of propionic acid, respectively. The fungal spoilage of high-moisture wheat grains inoculated with pure fungal spores and with naturally occurring fungi could be completely inhibited by 1.66 mmol/L hexanal vapor. During 5-week storage of high-moisture wheat grains fumigated with 1.66, 2.49, and 3.31 mmol/L hexanal vapor, the malondialdehyde content in high-moisture wheat grains did not change significantly in all samples, and fatty acid values were slightly higher in 18% moisture wheat than in 16% moisture wheat. The germination percentages and vigor of wheat samples decreased with increased hexanal vapor concentrations and moisture content. These results indicated that hexanal fumigation could be used as an alternative chemical control method to prevent the fungal spoilage of postharvest wheat.

We previously showed that L-arginine (Arg) accumulates in colorectal cancer tissues. The aim of this study was to investigate the mechanism by which Arg accumulates and determine its biological significance. The concentration of Arg and Citrulline (Cit) in sera and tumor tissues from colorectal cancer (CRC) patients was analyzed by high-performance liquid chromatography (HPLC). The expression of Arg transporters was analyzed by quantitative reverse transcription polymerase chain reaction (qRT-PCR) and immunohistochemical analysis of tissue microarray. We also transfected the colon cancer cell line HCT-116 with siRNA specific for the Arg transporter CAT-1 and measured the induction of apoptosis by flow cytometry and cell proliferation by MTT assay. Consistent with our previous results, serum Arg and Cit concentrations in colorectal cancer patients were significantly lower than those in normal volunteers, while Arg and Cit concentrations in colorectal cancer tissues were significantly higher than in matched adjacent normal colon tissues. Quantitative RT-PCR showed that the CAT-1 gene was highly overexpressed in 70.5% of colorectal cancer tissue samples relative to adjacent normal colon tissues in all 122 patients with colorectal cancer. Immunohistochemical analysis of tissue microarray confirmed that the expression of CAT-1 was higher in all 25 colorectal cancer tissues tested. CAT-1 siRNA significantly induced apoptosis of HCT-116 cells and subsequently inhibited cell growth by 20-50%. Our findings indicate that accumulation of L-Arg and Cit and cell growth in colorectal cancer tissues is associated with over-expression of the Arg transporter gene CAT-1. Our results may be useful for the development of molecular diagnostic tools and targeted therapy for colorectal cancer.