Fumonisin is a type of mycotoxin produced by the fungus Fusarium spp. It has been established as the causative agent of pulmonary oedema in pigs and leukoencephalomalacia in horses. Fumonisin is frequently detected in corn ears, and its level increases after the yellow ripe stage. However, details of the actual distribution of fumonisin in a corn plant are unknown. It, therefore, becomes very arduous to measure the effects of fumonisin. This study was undertaken to ascertain the distribution of fumonisin in the different areas of corn ear.
We cultivated four varieties of corns, namely A, B, C, and D. In each of the 4 varieties, the corn ears that exhibited significant symptoms of Fusarium ear rot were sampled during the late yellow ripe stage. Each corn ear was separated into 3 parts, viz., the bract, upper half of the ear (excluding the bract), and lower half of the ear (excluding the bract). Fumonisin (B1+B2) concentration in all three parts was quantified for each variety of corn.
The average concentration of fumonisin in the different parts of the ear was as follows: Bract: variety A, 730 μg/kg dry matter (DM); variety B, 240 μg/kg DM; variety C, 660 μg/kg DM; and variety D, 240 μg/kg DM; upper half of the ear: variety A, 17,000 μg/kg DM; variety B, 19,000 μg/kg DM; variety C, 25,000 μg/kg DM; and variety D, 20,000 μg/kg DM; lower half of the ear: variety A, 17 μg/kg DM; variety B, 630 μg/kg DM; variety C, 230 μg/kg DM; and variety D; 80 μg/kg DM.
Our results demonstrate that in the assessed corn varieties showing symptoms of Fusarium ear rot, we observed two distinct regions of very high fumonisin concentration and relatively low fumonisin concentration. High fumonisin concentration regions were found in the regions showing the symptoms of Fusarium ear rot. The consistency of this observation in all the varieties suggests that fumonisin is not uniformly distributed in the corn ear and it is localized to the site of the symptoms.
(Pathology and Pathophysiology Research Division)
References:
Uegaki R. et al (2014) Mycotox. Res. 31:51-56
