Tetraploid Tunisian Wheat Germplasm as a New Source of Fusarium Head Blight Resistance

Fusarium head blight (FHB) caused by Fusarium graminearum Schwabe causes extensive losses in durum wheat [Triticum turgidum subsp. durum (Desf.) Husn.]. The only verified resistance contributed by a tetraploid wheat species comes from T. turgidum L. subsp. dicoccoides (Korn. ex Asch. & Graebn.) Thell. This research was conducted to determine whether five Tunisian durum lines exhibiting Type II FHB resistance carry the same resistance alleles as the hexaploid wheat 'Frontana', 'Sumai 3', and 'Wangshuibai' and subsp. dicoccoides genotype (Israel A). One hundred thirty-one polymerase chain reaction (PCR)-based markers were used to determine the genetic similarity among 20 genotypes including resistant and susceptible Tunisian lines and adapted tetraploid and hexaploid cultivars. Phenotypic evaluation was conducted in two greenhouse seasons. Cluster analysis of the Tunisian lines based on the genetic markers showed they are genetically distant from known sources of resistance. Tunisian 7, the most resistant line in this study, was distinctly placed on a separate branch from all the other Tunisian lines, indicating the presence of some genetic diversity. Nineteen of the genotypes were haplotyped with PCR-based markers for nine loci on six chromosomes associated with known Type II FHB resistance. The Tunisian lines amplified different fragment sizes from the known resistant hexaploid wheat cultivars and subsp. dicoccoides. Results from this study indicate that these Tunisian lines may contain a novel source of Type II FHB resistance.