Maize Endosperm Proteins Associated with Aflatoxin Resistance

Infection of maize kernels before harvest and during storage by the fungus Aspergillus flavus and subsequent contamination with aflatoxins is a serious problem for maize growers worldwide. The dominant aflatoxin produced during the infection is B1, the most potent carcinogen produced in nature. Although several maize genotypes are known to resist aflatoxin accumulation, progress in incorporating the resistance to lines with desirable agronomic properties has been slow, mainly due to the absence of genetic markers linked with resistance.

By identifying the proteins associated with aflatoxin contamination in maize, researchers from the United States Department of Agriculture expect to discover proteins that can be used in marker-assisted breeding strategies. Expressions of over a dozen of constitutive kernel embryo proteins, mostly related to storage, defense and stress adaptation, were found to be associated with resistance. A specific protein, glyoxalase I, revealed a potentially important role in resistance through controlling the level of its substrate, methylglyoxal, which is an aflatoxin inducer. Disease defense and antioxidant proteins were also found to be expressed at a higher level in resistant lines than in susceptible ones. Studies are now being made to identify marker genes to further assist the development of aflatoxin resistant maize lines.

Read the abstract at http://apsjournals.apsnet.org/doi/abs/10.1094/PHYTO-97-9-1094 or the full paper at http://apsjournals.apsnet.org/doi/pdfplus/10.1094/PHYTO-97-9-1094