Microbiome Analysis Revealed the Effects of Environmental Factors on the Presence of Toxigenic Fungi and Toxin Production in Rice Grains

Fungal contamination in rice and mycotoxins present significant challenges to both rice quality and food safety. However, there is a dearth of comprehensive research on the compositional and structural changes within fungal colonies in rice, particularly in typical rice-producing regions, as well as their underlying influencing factors. In this study, a comprehensive analysis of fungal taxa in rice grains was conducted using amplicon sequencing and bioinformatics methods on 99 rice samples collected in three major rice-producing regions in China: Northeast Plain (NP), Yangtze River Basin (YR), and Southeast Coastal Area (SC). A total of 6,019,722 fungal ITS sequences were obtained with an average sequence length of 235 base pairs, and effective ASVs (2014) accounted for approximately 97.58% of the total ASVs (2064). The fungal community diversity in rice grains exhibited significant variations across the three regions, with deterministic processes playing a predominant role in shaping the ecological dynamics of fungal taxa. Among the core microbiota (92 shared ASVs), the first five species (Alternaria, Fusarium, Curvularia, Epicoccum, and Ustilaginoidea) accounting for a proportion greater than 5% had been reported as potential pathogens for plants. Geographical variations in fungal community composition were evident, with a significantly higher number of shared populations observed between YR and CS regions compared to those in the NP region. Nutrient elements and climatic conditions were the internal and external driving factors of rice fungal community composition. Additionally, notable regional variations in fungal functionality were observed. The findings have significant implications for gaining a comprehensive understanding of the distribution patterns of fungal communities in the major rice-producing regions in China. Additionally, it provides valuable insights into controlling key influencing factors to effectively reduce the occurrence of toxin-producing fungi and mitigate the associated risks related to mycotoxin contamination, thereby contributing to improved risk management and assessment.