Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: 6/30/2002
Publication Date: 6/30/2002
Citation: CURLEY, J., WARNKE, S., BARKER, R.E., LEONG, S., JUNG, G. GENETIC VARIABILITY AND QTL MAPPING OF RESISTANCE TO GRAY LEAF SPOT IN A LOLIUM PSEUDO-TESTCROSS POPULATION.. PHYTOPATHOLOGY. 2002. v. 92(S17). p. 291-302.
Technical Abstract: Gray leaf spot (GLS) is a serious fungal disease on the important turf and forage species, perennial ryegrass (Lolium perenne) caused by the rice blast fungus Magnaporthe grisea. Early reports suggest little resistance is present in perennial ryegrass cultivars. However, greenhouse inoculations in our lab using several rice and ryegrass isolates suggests some resistance is present, both in sixteen F1 clones derived from crosses among individual clones of cultivars, and in a subsample of progenies from an annual × perennial ryegrass (MFA × MFB) F2 pseudo-testcross population. These two groups of genotypes varied widely in resistance, as measured by lesion type and severity. The results were generally consistent, and the clones MFA and MFB were generally more tolerant than others. Also, the progeny subsample, when scored by the most severe lesion present of the three replicates, appears to segregate in a 1:2:1 ratio, though this needs confirmation. Thus, both the MFA × MFB population and the F1 genotypes show potential for use in quantitative trait locus (QTL) mapping and resistance breeding through recurrent selection. This study will examine variability in resistance, select parents for a new F2 pseudo-testcross mapping population, and make crosses. Also, genetic linkage map construction will begin using AFLP and RAPD markers, and RFLP synteny anchor probes from cereal crops. A partial map has already been constructed for the existing MFA × MFB population, and the phenotypic segregation seen in the subsample will enable QTL analysis in this population. With this information, locations and effects of QTL for GLS resistance in both rice and ryegrass can be compared via comparative QTL mapping in two different populations, which can then lead to map-based cloning of novel resistance genes in both species.