Fusarium spp. is one of the most dangerous fungal pathogens, causing substantial economic losses worldwide by reducing crop yield and producing mycotoxins. Photosensitization is a novel, non-thermal, and effective technology for inactivating fungi. However, there were not many studies on controlling Fusarium growth and mycotoxin production using photosensitization. In this study, we investigated the effects of three natural photosensitizers, including menadione sodium bisulfite (MSB), coumarin and curcumin, on inhibiting the growth of Fusarium graminearum both in vitro and in wheat in the field. In general, photosensitization effectively inhibited spore germination and mycelial growth of the two tested F. graminearum isolates (10-124-1 and 10-125-1) in a dose-dependent manner, with MSB showing a more pronounced effect. For example, 50% spore germination inhibition rates (EC₅₀) were observed at 3.07 mM/mL and 1.61 mM/mL, respectively, after treating with MSB and coumarin, along with UV light exposure at 233 J/cm² for 30 mins in isolate 10-124-1. According to results from scanning electron microscopy (SEM), fluorescence spectroscopy, and confocal laser scanning microscopy (CLSM), the generated intracellular reactive oxygen species (ROS) oxidized lipid and/or protein in cell membranes. This led to the observation of shrunken spores and mycelial with rough, corrugated surfaces due to significant loss of the cytoplasmic matrix. Furthermore, the impact of PS on inhibiting Fusarium spp. growth and mycotoxin production in wheat in the field was investigated. The susceptible wheaton cultivars were planted in 20 rows following a randomized complete block design (RCBD) with five blocks. During the flowering stage, the wheaton cultivars were point inoculated with a mixture of Fusarium spp. and the application of photosensitizers (curcumin, MSB, and coumarin) was applied at two different timings of a day after one day of point inoculation. The FHB scoring data was recorded after 17 days and 21 days of infection. Although the results of FHB scoring didn’t show statistically significant reductions in Fusarium infection at P<0.05 by the applications of three PS. However, some data points of FHB scoring have shown promising results due to the application of curcumin and MSB. In addition, FHB scoring data was correlated with the mycotoxin data. For example, DON has shown significant lower level at p<0.05 for curcumin treated seeds as compared to control. In addition, spraying time also plays an important role on mycotoxin production. NIV demonstrated significant differences at p<0.05 for three different PSs compared to control samples in morning-sprayed samples, as opposed to those in the evening.

ACKNOWLEDGEMENT AND DISCLAIMER

This material is based upon work supported by the U.S. Wheat and Barley Scab Initiative under Agreement No. 59-0206-2-131. Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the authors and do not necessarily reflect the view of the U.S. Department of Agriculture.