PHENOTYPIC AND GENOTYPIC SELECTION FOR HEAD SCAB RESISTANCE IN WHEAT

• Main Author: Agostinelli, Andres Mateo
• Format: Others
• Published: UKnowledge 2009
• Subjects: Fusarium head blight; Triticum aestivum; deoxynivalenol (DON); resistance; quantitative trait loci (QTL); Agronomy and Crop Sciences
• Online Access: http://uknowledge.uky.edu/gradschool_theses/582; http://uknowledge.uky.edu/cgi/viewcontent.cgi?article=1586&context=gradschool_theses

Fusarium Head Blight (FHB) is a destructive disease caused by Fusarium graminearum that affects wheat (Triticum aestivum L.) worldwide. Breeding for resistance to FHB is arguably the best way to combat this disease. However, FHB resistance is highly complex and phenotypic screening is difficult. Molecular markers are a promising tool but breeding programs face the challenge of allocating resources in such a way that the optimum balance between phenotypic and genotypic selection is reached. An F2:3 population derived from a resistant x susceptible cross was subjected to phenotypic and genotypic selection. For phenotyping, a novel air separation method was used to measure percentage of damaged kernels (FDK). Heritability estimates were remarkably high, which was attributed to the type of cross and the quality of phenotyping. Genotypic selection was done by selecting resistance alleles at quantitative trait loci (QTL) on the 3BS (Fhb1) and the 2DL chromosomes. Fhb1 conferred a moderate but stable FHB resistance while the 2DL QTL conferred a surprisingly high level of resistance but with significant interaction with the environment. Phenotypic selection conferred higher or lower genetic gains than genotypic selection, depending on the selection intensity. Based on these results, different selection strategies are discussed.