Genetic analysis of Aspergillus Flavus infection and aflatoxin accumulation in tropical yellow maize

Authors: SSERUMAGA, JULIUS - National Agricultural Research Organization - Uganda; MAKUMBI, DAN - International Maize & Wheat Improvement Center (CIMMYT); OBUA, TONNY - Makerere University; NGANGA, FREDERICK - International Livestock Research Institute (ILRI) - Kenya; ZIYOMO, CATHERINE - International Crops Research Institute For The Semi-Arid Tropics (ICRISAT); JUMBO, BRIGHT - International Maize & Wheat Improvement Center (CIMMYT); BRUCE, ANANI - International Maize & Wheat Improvement Center (CIMMYT); Jeffers, Daniel; Smith, Jesse; Warburton, Marilyn

Submitted to: Phytoparasitica
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/25/2026
Publication Date: 4/1/2026
Citation: Sserumaga, J.P., Makumbi, D., Obua, T., Nganga, F., Ziyomo, C., Jumbo, B.M., Bruce, A.Y., Jeffers, D., Smith, J.S., Warburton, M.L. 2026. Genetic analysis of Aspergillus Flavus infection and aflatoxin accumulation in tropical yellow maize. Phytoparasitica. 54.Article 44. https://doi.org/10.1007/s12600-026-01376-w.
DOI: https://doi.org/10.1007/s12600-026-01376-w

Interpretive Summary: Yellow maize, which is known to have high vitamin levels, is susceptible to fungal infection by Aspergillus flavus, which creates a toxic substance in the kernels called aflatoxin. This study investigated the genetics of maize resistance to A. flavus and aflatoxin accumulation in 19 tropical inbred lines and all possible hybrid combinations between them. Genetic resistance was identified, and seven inbred lines made good resistant parents. We present here the availability of potential parental lines for breeding programs targeting resistance to this fungal pathogen and its toxic by-products.

Technical Abstract: Yellow maize, which is known to have high carotenoid levels, is susceptible to Aspergillus flavus infection and subsequent aflatoxin contamination. This study investigated the genetics of resistance to A. flavus and aflatoxin accumulation in 19 inbred lines and their 171 diallel hybrids evaluated across two locations, and under laboratory conditions. Kernels from the lines and hybrids were inoculated with toxigenic A. flavus, and aflatoxin content was measured 21 days after inoculation to estimate percent kernel infection (PKI3) using ELISA. Significant genetic variation was observed for PKI3, aflatoxin accumulation, and agronomic traits. General combining ability (GCA) was of greater magnitude than specific combining ability (SCA) for most traits, suggesting the predominance of additive genetic effects. Five inbred lines exhibited significant (P < 0.05) negative GCA effects for kernel infection, while two lines (CML496 and CKL187031) showed significant (P < 0.05) GCA effects for reduced aflatoxin accumulation. Inbred line CKL187031 exhibited desirable GCA effects for both and reduced aflatoxin accumulation. The number of groups of genes controlling kernel infection and aflatoxin accumulation was estimated to be four and six, respectively. Broad-sense heritability was moderate to high (H2 = 0.59 to 0.80) for agronomic traits, but low for aflatoxin resistance parameters (H2 = 0.28) in hybrids. Aflatoxin content in the top 15 hybrids ranged from 2.89 to 5.35 ng g-1. These results indicate the presence of genetic variability in tropical yellow maize germplasm, highlighting the availability of potential parental lines for breeding programs targeting resistance to A. flavus.