Genotypic variability in maize for aflatoxin contamination

A total of 60 maize genotype samples from different agroclimatic regions of India were collected. Fresh harvest of these maize samples comprising some commercial maize genotypes and some land races were kept under ambient storage conditions for 9 months duration at grain moisture ranges from 14% to 10.5% with a view to identifying the least contaminated maize genotype with aflatoxin. The purpose of this study was to identify the maize genotypes which can survive in ambient storage conditions with minimum spoilage. The response of various maize genotypes for AFB₁ accumulation was variable in similar storage conditions. Promising genotypes which showed lower accumulation of AFB₁ were identified: Shaktiman-1 (A QPM variety) by showing the lowest concentration of AFB₁ (0.30 ppb) followed by KMH-1701 (0.40 ppb); HQPM-1 (0.50 ppb); and QPM-2- 136 (0.60 ppb), whereas the most highly toxic sample was Mon - 4 (62.42 ppb) at grain moisture ranges from 12.6 to 11.1%. During the study it has been observed that Shaktiman-1 and other QPM genotypes showed minimum levels of AFB₁. Further, it was confirmed by western blot analysis by comparing the resistant and susceptible genotype under artificially inoculated grains with Aspergillus flavus and uninoculated maize grains. It was observed that more chitinase activity was found in shaktiman-1, when the grains were artificially inoculated with A. flavus. The thickness of the seed coat and Aleuron layer was maximum in (90-100 μm) in Shaktiman compared to that of Pro-311 (80-85 μm). It was observed that the thickness of seed coat may act as a barrier for mold contamination and as a result the storage spoilage is minimised.