Molecular mapping of [Regent x Lemberger] and QTL-analysis of agronomic traits

A crossing population was established to characterize quantitative trait loci of agronomically important traits and to elucidate basic principles of quantitative resistance in European type grapevine. Regent (female parent) copes well with fungal .attack in field trials, whereas Lemberger (male parent) represents a traditional susceptible cultivar, The progeny comprising 153 individuals segregate for resistance to Plasmopara viticola and Uncinula necator and for other agronomic trails such as onset of berry ripening, bunch• and berry characteristics. Phenotypes were scored repeatedly for these quantitative traits over a period of six years. A dense linkage map of molecular markers (AFLP, RAPD, SSR, CAPS of characterized genes) was established for both parents using Mapmaker and Joinmap software under a high stringency of LODS. These maps were aligned by anchor markers. In QTL interval mapping some of the traits under investigation showed reproducible and significant LOD score profiles. One objective of the project is to approach map-based cloning. To envisage this aim, marker fragments which map to QTL peak regions are currently under investigation.