Molecular markers to increase corn earworm resistance in a maize population

Maysin and related compounds, such as apimaysin, 3 ' -methoxymaysin, and ch lorogenic acid, have been determined to be important maize (Zea mays L.) pr oduced antibiotic compounds against corn earworm (Helicoverpa zea Boddie), but, to be effective under field conditions, silk antibiotics should be acc ompanied by good husk coverage. The objective of this work was to identify molecular markers associated with synthesis of maysin and related compounds in a maize Population and determine if the markers could be linked to the genes which affect husk tightness. A total of 113 probes were used to scree n for RFLP polymorphisms and the 53 probes that were polymorphic between th e parents were used as codominant markers to genotype 205 F-2 individuals. Silks and husks of F-2:3 families were evaluated. Two major QTL were identi fied for the synthesis of maysin and related compounds, the already known p l, on the short arm of chromosome 1, and a novel one on the interval csu106 6-umcl76 on genomic region 2C-2L. A QTL for husk tightness was located near pl. The functional allele for pi and the favorable allele for husk tightne ss were in repulsion linkage. in a marker-assisted selection program for in creasing resistance to corn earworm, markers for silk antibiotic synthesis should be accompanied by markers for husk tightness. Efforts Should be made to convert the RFLP-markers into PCR-based markers for user friendly appli cation in marker-assisted breeding.