Grain Development and Aflatoxin B₁ Accumulation in Preharvest Rice Inoculated with Aspergillus parasiticus

A rice cultivar (Japonica type), Cheong-cheong , was planted in a rice paddy in Southern Korea to examine the effects of Aspergillus parasiticus infection on the development of the grains. The grain was inoculated with the fungal inoculum at the milk stage of development. Ripening rates, 100-grain weights and aflatoxin B₁ accumulation were observed at harvest. An enzyme-linked immunosorbent assay (ELISA) and immunohistochemical staining were performed to detect and confirm aflatoxin B₁ in the samples. When the rice grains were inoculated with A. parasiticus the ripening rates (number of fully matured grains per total number of grains in a panicle) were not significantly different from the control samples. Examination of 100-grain weights showed no significant difference between the groups. The edible portion of inoculated grain exhibited significantly higher levels of toxins than did the rice hulls, and the embryo contained a higher proportion of toxins than the endosperm (P < 0.05). The immunohistochemical staining revealed positive findings for the embryo of inoculated grains, but not for the control embryo.