Genetic improvement of resistance to ear rot caused by Fusarium graminearum in early maturing maize by QTL mapping in multiple crosses

Gibberella ear rot (GER) of maize (Zea mays L.) mainly caused by Fusarium graminearum Schwabe is a major disease in Germany. It lowers yields and contaminates the grain with mycotoxins. Two important mycotoxins produced by F. graminearum are deoxynivalenol (DON) and zearalenone (ZEA), which belong to the major contaminants of grain in Germany. DON and ZEA adversely affect the health of humans and animals. There is no fungicidal control of GER in maize so far and cultural practices have only limited effect on infection and mycotoxin contamination. Therefore, deployment of genetic resistance to ear rots is the best option.

The objective of this study is to identify chromosomal regions (QTL) governing GER resistance and reduced mycotoxin contamination, which could be used for the genetic improvement of these traits in adapted maize germplasm. We evaluated different populations derived from multiple crosses of common parents, identified several QTL for GER resistance and reduced DON and ZEA contamination, and found congruency of some QTL locations across populations.

Our study indicated that selection for GER resistance and reduced mycotoxin contamination should be performed based on a combination of classical phenotypic and marker-assisted selection. Further, relatively weak relationships of GER resistance and mycotoxin contamination of lines with their testcrosses showed the need for additional testing of testcrosses in applied breeding programs. In conclusion, our results provide a good basis for a sustainable enhancement of GER resistance in early maize.