Using biotechnology to enhance host resistance to aflatoxin contamination of corn

Abstract

Host resistance is the most widely explored strategy for eliminating aflatoxin contamination by Aspergillus flavus. Breeding strategies for developing resistant corn germplasm have been enhanced by the development of new screening tools for field inoculation and for laboratory screening. RFLP analysis of corn populations has highlighted the possibility that different resistance traits can be successfully pyramided into agronomically useful germplasm, while proteomics has impacted the identification of proteins associated with resistance (RAPs). The identification of RAPs has also been enhanced by the discovery of near-isogenic corn lines in progeny generated in a West African breeding program. The characterization of genes of the aflatoxin biosynthetic pathway has provided a foundation for a genomics investigation aimed at understanding the biochemical function and genetic regulation of aflatoxin biosynthesis. Successful inhibition of aflatoxin elaboration may require not only the action of antifungal compounds, but of compounds that block biosynthesis of toxins as well.

Review of good agricultural practices for smallholder maize farmers to minimise aflatoxin contamination

“…If the maize variety is not resilient it may be vulnerable to drought, insects, pathogens, etc. (Brown et al, 2003(Brown et al, , 2013Chen et al, 2001;Menkir et al, 2008) to the locality and approved by the local country as seed material. Several screening tools have been developed and used to facilitate maize breeding for developing germplasm resistant to fungal growth and/or aflatoxin contamination (Brown et al, 2003).…”

“…(Brown et al, 2003(Brown et al, , 2013Chen et al, 2001;Menkir et al, 2008) to the locality and approved by the local country as seed material. Several screening tools have been developed and used to facilitate maize breeding for developing germplasm resistant to fungal growth and/or aflatoxin contamination (Brown et al, 2003). Sources of resistance to Aspergillus infection and aflatoxin contamination in maize have been identified, but commercial hybrids have not been developed.…”

“…This is largely due to the difficulty in finding elite lines that maintain high yields and resistance within multiple environments (Clements and White, 2008). Brown et al (2003) tested aflatoxin resistance in 36 inbred maize lines that were selected in West and Central Africa for moderate to high resistance to maize ear rot. More than half the inbred lines accumulated aflatoxins at levels as low as, or lower than, the resistant US lines.…”

Identifying and developing maize germplasm with resistance to accumulation of aflatoxins

“…The identification of several types of resistance traits could significantly enhance the development of resistant commercial lines by facilitating a strategy of pyramiding different resistance genes into good agronomic backgrounds. The resistant US genotypes and inbred lines from IITA, which were screened using the KSA, provide the basis for selecting parental lines in an on-going collaborative resistance-breeding project (Brown et al, 2003).…”

“…The complex nature of inheritance of resistance, the erratic nature of field infection by A. flavus and the year-to-year variability in aflatoxin levels have limited transfer of resistance to elite maize inbred lines (Brooks et al, 2005;Gorman and Kang, 1991). The advent of new and efficient tools for screening maize genotypes in the field and laboratory has enhanced breeding strategies for developing resistant maize (Brown et al, 2003).…”