Resistance to aflatoxin contamination in corn as influenced by relative humidity and kernel germination

• Published in: Journal of food protection 1996-03, Vol.59 (3), p.276-281
• Main Authors: Guo, B.Z. (Louisiana State University Agricultural Center, Baton Rouge, LA.), Russin, J.S, Brown, R.L, Cleveland, T.E, Widstrom, N.W
• Format: Article
• Language: English
• Subjects: AFLATOXINAS; AFLATOXINE; Aflatoxins - biosynthesis; ALIMENTOS; AMANDE DE LA GRAINE; ASPERGILLUS FLAVUS; Aspergillus flavus - growth & development; Aspergillus flavus - metabolism; Biological and medical sciences; Cereal and baking product industries; CONTAMINACION; CONTAMINATION; Food industries; Fundamental and applied biological sciences. Psychology; Fungal plant pathogens; GENOTIPOS; GENOTYPE; GERMEN; GERMINACION; GERMINATION; HUMEDAD RELATIVA; HUMIDITE RELATIVE; Humidity; INHIBICION; INHIBITION; INNOCUITE DES PRODUITS ALIMENTAIRES; INOCUIDAD ALIMENTARIA; MAIS; MAIZ; Pathology, epidemiology, host-fungus relationships. Damages, economic importance; Phytopathology. Animal pests. Plant and forest protection; PRODUIT ALIMENTAIRE; Seeds - growth & development; Zea mays; Zea mays - genetics; Zea mays - growth & development; Zea mays - microbiology
• ISSN: 0362-028X; 1944-9097
• DOI: 10.4315/0362-028X-59.3.276

Kernels of corn population GT-MAS:gk, resistant to aflatoxin B1 production by Aspergillus flavus, and susceptible Pioneer hybrid 3154 were tested for aflatoxin when incubated under different relative humidities (RH). High aflatoxin levels were not detected in either genotype at RH 91%. Resistance in GT-MAS:gk was consistent across all RH levels (91 to 100%) at which significant aflatoxin accumulation was detected. Aflatoxin levels in GT-MAS:gk averaged about 98% less than those in susceptible Pioneer 3154, which suggests that storage of this or other genotypes with similar resistance mechanisms may be possible under moisture conditions less exacting than are required with susceptible hybrids. Results for fungus growth and sporulation ratings on kernel surfaces were similar to those for aflatoxin levels. When kernels of both genotypes were preincubated 3 days at 100% RH prior to inoculation with A. flavus, germination percentages increased to very high levels compared to those of kernels that were not preincubated. In preincubated kernels aflatoxin levels remained consistently low in GT-MAS:gk but decreased markedly (61%) in Pioneer 3154. When eight susceptible hybrids were evaluated for aflatoxin accumulation in preincubated kernels, seven of these supported significantly lower toxin levels than kernels not subjected to preincubation. Average reduction across hybrids was 83%, and reductions within hybrids ranged from 68 to 96%. Preincubated kernels of one susceptible hybrid (Deltapine G-4666) supported aflatoxin levels comparable to those in resistant GT-MAS:gk. Data suggest that an inhibitor of aflatoxin biosynthesis may be induced during kernel germination Possible mechanisms for embryo effects on resistance to aflatoxin accumulation are discussed