Abstract only

Aflatoxins have emerged as a major concern in agriculture and health sectors because of their deleterious effects on human and animal health and ubiquitous presence of aflatoxigenic fungi in many agricultural commodities under field and storage conditions. Although several strategies can be used to aflatoxins, no single strategy has been effective. An integrated approach that emphasize host plant resistance as the main component is most likely to be effective, as use of resistant varieties and hybrids is the most economic and user friendly strategy, especially for small holder farmers in developing countries. To date, no varieties or hybrids with complete resistance have been developed. This is because the extent of aflatoxin contamination of maize is influenced by several abiotic (such as drought, low soil fertility and high temperatures).and biotic (such as insect damage, and susceptibility to diseases) factors, and several plant traits (husk cover and tightness, physical and chemical characteristics of the pericarp). The plethora of characteristics associated with tolerance / resistance to A. flavus and aflatoxin contamination reveal the complexity of this trait and why no single strategy is likely to be effective. A combination of approaches designed to prevent the fungus from reaching and invading the crop, prevent the fungus from colonizing, spreading and producing the toxin need to be harnessed to develop A. flavus and aflatoxin resistant / tolerant maize lines and hybrids. CIMMYT has successfully identified and developed maize lines and hybrids with high levels of resistance to biotic (insect pest and pathogens), and abiotic stresses (drought, and low N), and has identified several inbred lines with acceptable levels of A. flavus resistance (such as CML 269, CML 176, CML495, CML 52, CML 342). We are combining tolerance to drought, low nitrogen with resistance to ear feeding insects, foliar diseases, A. flavus and aflatoxin, to generate lines and hybrids with resistance to aspergillus ear rots and aflatoxin, and improved agronomic performance. Progress to developing multiple stress tolerant germplasm will depend on (i) availability of well validated sources of A. flavus and aflatoxin resistance, and other predisposing factors (ii) reliable phenotyping protocols and capacity to screen large segregating populations; and (iii) availability of robust and cheap techniques to quantify aflatoxin. We are using the doubled haploid (DH) technology to rapidly develop homozygous multiple stress resistant inbred lines and accelerate the development and use of genetic traits to manage aspergilus ear rots and aflatoxin contamination of maize.

Global Maize Program

Text in English

INT2822

CIMMYT Staff Publications Collection