Microgametophytic selection for identifying maize with resistance to Aspergillus spp. and aflatoxin

ABSTRACT

Aflatoxin B₁, produced by Aspergillus flavus Link ex Fries and A. parasiticus Speare on maize (Zea mays L.), is a potent carcinogen that is linked to liver cancer in animals and humans. Normally, genetic materials are field-inoculated and evaluated by conducting aflatoxin assays in the laboratory to develop host resistance (sporophytic selection). These procedures are costly and time-consuming and limit the amount of genetic material that can be evaluated. Microgametophytic selection (pollen selection) in maize has not been explored for screening genetic material for resistance to Aspergillus spp. and aflatoxin. The objective of this investigation was to examine in vitro pollen germination in the presence of A. flavus and A. parasiticus conidia, and aflatoxin B₁ in the F₂ generation of a cross between Mp313E (resistant inbred) and SC212M (susceptible inbred). A. flavus conidia significantly inhibited pollen grain germination in comparison with the control and the other two treatments. A. parasiticus and aflatoxin B₁ treatments did not differ significantly from each other but differed from the control, suggesting that A. flavus conidia, instead of aflatoxin, could be used for screening germplasm for resistance to Aspergillus and/or aflatoxin. We concluded that pollen grains containing genes for susceptibility to A. flavus can be eliminated in a segregating population and that microgametophytic screening could greatly facilitate recurrent selection and screening of germplasm for resistance to aflatoxin at a much less cost and in a shorter period than field testing. Pollen grains carrying resistance genes can be manipulated to develop recombinant inbred lines to accelerate development of parental inbred lines to produce hybrids possessing tolerance to A. flavus and/or aflatoxin B₁.

KEYWORDS:

• Gametophytic selection
• in vitro selection
• pollen germination
• recurrent selection
• resistant germplasm
• sporophytic selection
• Zea mays

Disclosure statement

No potential conflict of interest was reported by the authors.