Identification of sources of resistance against Aspergillus flavus and aflatoxin contamination in maize cultivars using molecular and kernel screening assay

Maize (Zea mays L.) is a main cereal crop for livestock and human consumption worldwide. Maize production must increase by 70 % by 2050 to feed the growing population. However, the crop has many challenges, including its suitability for aflatoxigenic fungus (Aspergillus flavus). The present study investigated the aflatoxigenic levels of twenty (20) maize cultivars using the lab-based kernel screening assay. The results revealed that the cultivar MHL517 (Provitamin A) had no detectable levels of aflatoxins (<nd) and a low colonization rate compared to the best resistance checks (RC212741 and RC 21166) used. The results reveal that Aflatoxin B1 and total Aflatoxin (TA) levels were high in Genotype SC173531 and TO 104 with (AFB1 = 714.3 µg/kg, TA = 662.6 µg/kg) and (AFB1 = 681.6 µg/kg, TA = 576.6 µg/kg), respectively, indicating its susceptibility to A. flavus. A PCR-based detection technique revealed the presence of the resistance TC23674 gene in resistant cultivars, including the resistant check inbred lines, that were not found in susceptible cultivars. The findings showed that maize grain exhibiting greater proVA and beta carotene concentrations had lower aflatoxin contamination than grain exhibiting lower carotenoid concentrations. The MHL517 cultivar was determined to be the most promising among the examined cultivars, and the study proposed that it may be used in commercial hybrids to develop fungal-resistant cultivars. Therefore, a higher level of proVA and beta carotene in maize can be a successful first line of defense against aflatoxin contamination.