Identification of quantitative trait loci for resistant to maize ear rot caused by Fusarium moniliforme Sheldon and common rust caused by Puccinia sorghi in Argentinian maize germplasm

Maize ear rot caused by Fusarium moniliforme Sheldon and common rust caused by Puccinia sorghi are two of the most important diseases in maize in Argentina. Variability for resistance in both diseases is observed between the two heterotic pools commonly used in maize breeding in Argentina. General resistance to ear rot has been reported and general or partial and race-specific resistance are available for rust. The objective of this work was to identify quantitative trait loci (QTL´s) associated to genetic resistance to both diseases and analyze the possibility of using the QTL´s in a marker-assisted selection program to reduce the amount of materials to screen in disease nurseries. A population of 190 F2:3 families of maize obtained in a cross between two inbreds belonging to both pools was evaluated for resistance to both diseases under artificial inoculation and natural infection respectively. One hundred and thirty simple sequence repeat (SSR) were used. Six and three putative resistant QTL´s to ear rot and rust were identified respectively using a single point linkage analysis. QTL´s explained up to 6.5% of phenotypic variation for ear rot and up to 27% for rust. These results suggest that , in relation to ear rot, marker assisted selection alone is not recommended for use on a routine basis, whereas its use, along with phenotypic scores in rust could be of value for selecting superiorgenotypes