Distribution of mycotoxin-producing fungi across major rice production areas of China

Mycotoxin contamination of rice (Oryza sativa), especially that from aflatoxins (AFTs), is one of the greatest chemical hazards to humans and animals. However, few studies have investigated the relationships between fungal communities and mycotoxin contamination of rice grains. In the present study, we collected rice grain samples from 10 provinces in the northeastern (NE), southeastern (SE), and southwestern (SW) regions of China, encompassing the major rice-producing areas of China. The Fungal diversities of rice grains were significantly different among different regions and significantly higher in the SE and SW regions compared to the NE region. Geographic location was highly associated with fungal community alpha and beta diversity differences. Environmental variables determined the distribution of fungal communities, with winter mean temperature (WMT), mean annual precipitation (MAP), harvest mean wind speed (HMW), and grain moisture (GM) being the most important factor shaping the fungal communities, and the higher HMW could significantly reduce the abundance of aflatoxigenic fungi and aflatoxins. The Aspergillus flavus and A. parasiticus were defined as the major AFT-producing fungal taxa observed in the SE and SW region communities. The NE region exhibited a lower risk of AFT contamination due to its much lower prevalence of toxigenic fungi. Furthermore, keystone taxa of co-occurrence network analyses indicated that species belonging to the genera Clonostachys, Cryptococcus, Hannaella, Leptosphaerulina, Leptosphaeria, Phaeosphaeria, Sarocladium, Sphaerulina, Wallemia and Ustilaginoidea exhibited abundances that were negatively correlated with AFT-producing fungal abundances and could potentially inhibit the growth of AFT-producing fungi. The results provide potentially important data for the strategic guidance of local rice grains storage in order to better control toxin contamination and improve grain quality.