http://orcid.org/0000-0002-7803-0301
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ABSTRACT
Aflatoxin, a carcinogenic toxin, is produced mainly by Aspergillus flavus and Aspergillus parasiticus. Contamination of maize (Zea mays L.) grain by these fungi occurs before harvest, and the easiest strategy to prevent this is to develop/use maize varieties resistant to Aspergillus spp. and aflatoxin accumulation. The objective of this investigation was to identify potential sources of resistance among 23 maize inbred lines (13 obtained from the MAIZE Competitive Grants Initiative, International Maize and Wheat Improvement Centre and 10 from Agricultural Research Council, South Africa). The inbred lines were planted in a randomized complete-block design at two locations each in Kenya and South Africa. Maize ears were inoculated at silking with three toxigenic strains of A. flavus. The inoculated ears in each plot were harvested at 12–18% moisture, dried, and visually assessed for Aspergillus ear rot (AER). Aflatoxin concentration in the kernels was determined using liquid chromatography–tandem mass spectrometry. Significant variation for both AER and aflatoxin concentration existed among the inbred lines at both locations in Kenya and one location in South Africa. Combined analysis revealed a significant (p < 0.001) lines × locations interaction for both AER and aflatoxin concentration. Higher incidences of AER (0–86.0%) and aflatoxin concentration (0.21–6.51 µg/kg) were recorded at Kiboko in Kenya than at the other three locations. A stronger genetic correlation (rG = 0.936, p < 0.0001) between the AER and aflatoxin concentration was recorded in Potchefstroom than at the other three locations. Repeatability of aflatoxin concentration was high at Kiboko (0.87) and Potchefstroom in South Africa (0.74). Three inbred lines, CML247, CML444, and CML495, emerged as potentially useful sources of resistance to AER and aflatoxin accumulation as they showed low levels of aflatoxin contamination in both localities in Kenya and in South Africa.
Acknowledgments
The authors thank Dr. K. Mashingaidze from the Agricultural Research Council–Grain Crops Institute (ARC-GCI), South Africa, for providing the inbred line seed; Dr. H. Vismer from the Medical Research Council – Programme on Mycotoxins and Experimental Carcinogenesis unit, South Africa, for providing the fungal isolates, and Drs M. van der Rijst and M. Booyse from ARC-Infruitec for statistical analyses.
Declaration of interest
The authors declare no conflict of interest.
Funding
The MAIZE Competitive Grants Initiative, International Maize and Wheat Improvement Centre (CIMMYT) and CGIAR, as well as the South African Maize Trust and the National Research Foundation (NRF) of South Africa (South Africa- Kenya Research Partnership Programme Bilateral; RPPB13102856988), and the National Commission for Science, Technology and Innovation (NACOSTI) of Kenya are acknowledged for funding this research.
Additional information
Funding
Notes on contributors
Sheila Okoth
Authors S.O., A.V. and B.C.F. conceived and designed the experiments. Authors B.C.F. and D.M. provided germplasm. H. S, L.J.R., I.B., M.M., S.O. and A.O. conducted all field trials and generated the data; D.M., and L.J.R. analyzed the data; S.O and D.M. wrote the manuscript.
Lindy Joy Rose
Authors S.O., A.V. and B.C.F. conceived and designed the experiments. Authors B.C.F. and D.M. provided germplasm. H. S, L.J.R., I.B., M.M., S.O. and A.O. conducted all field trials and generated the data; D.M., and L.J.R. analyzed the data; S.O and D.M. wrote the manuscript.
Abigael Ouko
Authors S.O., A.V. and B.C.F. conceived and designed the experiments. Authors B.C.F. and D.M. provided germplasm. H. S, L.J.R., I.B., M.M., S.O. and A.O. conducted all field trials and generated the data; D.M., and L.J.R. analyzed the data; S.O and D.M. wrote the manuscript.
Ilze Beukes
Authors S.O., A.V. and B.C.F. conceived and designed the experiments. Authors B.C.F. and D.M. provided germplasm. H. S, L.J.R., I.B., M.M., S.O. and A.O. conducted all field trials and generated the data; D.M., and L.J.R. analyzed the data; S.O and D.M. wrote the manuscript.
Henry Sila
Authors S.O., A.V. and B.C.F. conceived and designed the experiments. Authors B.C.F. and D.M. provided germplasm. H. S, L.J.R., I.B., M.M., S.O. and A.O. conducted all field trials and generated the data; D.M., and L.J.R. analyzed the data; S.O and D.M. wrote the manuscript.
Marili Mouton
Authors S.O., A.V. and B.C.F. conceived and designed the experiments. Authors B.C.F. and D.M. provided germplasm. H. S, L.J.R., I.B., M.M., S.O. and A.O. conducted all field trials and generated the data; D.M., and L.J.R. analyzed the data; S.O and D.M. wrote the manuscript.
Bradley Charles Flett
Authors S.O., A.V. and B.C.F. conceived and designed the experiments. Authors B.C.F. and D.M. provided germplasm. H. S, L.J.R., I.B., M.M., S.O. and A.O. conducted all field trials and generated the data; D.M., and L.J.R. analyzed the data; S.O and D.M. wrote the manuscript.
Dan Makumbi
Authors S.O., A.V. and B.C.F. conceived and designed the experiments. Authors B.C.F. and D.M. provided germplasm. H. S, L.J.R., I.B., M.M., S.O. and A.O. conducted all field trials and generated the data; D.M., and L.J.R. analyzed the data; S.O and D.M. wrote the manuscript.
Altus Viljoen
Authors S.O., A.V. and B.C.F. conceived and designed the experiments. Authors B.C.F. and D.M. provided germplasm. H. S, L.J.R., I.B., M.M., S.O. and A.O. conducted all field trials and generated the data; D.M., and L.J.R. analyzed the data; S.O and D.M. wrote the manuscript.