Adaptation of the quantitative PCR method for the detection of the main representatives of cereal grain mycobiota

Abstract

The content of fungal DNA and mycotoxins in cereal crops (31 varieties of wheat, oats, and barley) was quantitatively determined and used for the comparative characterization of grains. The quantitative PCR has been adapted for the analysis of the target DNA of Alternaria spp., Bipolaris sorokiniana (B. sorokiniana) , Fusarium graminearum (F. graminearum) , F. culmorum , and F. sporotrichioides fungi, which are often present in the mycobiota of small grain cereals. The content of the DNA of the aggressive pathogen B. sorokiniana was determined using quantitative PCR for the first time. The DNA of Alternaria fungi was found abundantly in all grain samples, but its content in the oat was significantly higher compared to barley and wheat (5 and 9 times higher, respectively). In barley grain, the content of B. sorokiniana DNA was on average significantly higher than in the grains of oats and wheat. All of the analyzed grain samples contained the DNA of F. graminearum while F. culmorum DNA was found in 70% of the oat samples and in all of the samples of barley and wheat. Mycotoxin deoxynivalenol (DON) produced by these fungi was detected in all the analyzed cereal grains in a range from 77 to 4,133 μg/kg. The DNA of F. sporotrichioides was detected in 70% of oats and 50% of barley samples but was not found in wheat. The T-2 toxin produced by this fungus was detected in 45% of all samples within a range from 2 to 89 μg/kg. The statistically significant positive correlation with the Pearson correlation coefficient (r) equal to 0.49 (p<0.05) was observed between the content of F. graminearum DNA and the amount of DON in the grain samples. Another significant positive correlation (r=0.72, p<0.01) was found between the DNA contents of Alternaria fungi and F. sporotrichioides in the grain samples. This leads to the suggestion that conditions for the growth of these fungi in grain substrates are similar.