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Durum wheat ( Triticum turgidum L., 2 n = 4 x = 28; AABB genomes) is an important cereal crop widely used for human consumption. Fusarium head blight (FHB), or scab, caused by the fungus Fusarium graminearum Schwabe, is a serious disease of durum wheat. Current durum cultivars have very little or no FHB resistance. A wild relative, diploid wheatgrass Lophopyrum elongatum (Host) Á. Löve (2 n = 2 x = 14; EE genome) is an excellent source of resistance. By crossing durum wheat with L. elongatum we produced F 1 hybrids that were male sterile. By backcrossing the F1 hybrids to the durum parent, followed by selfing, we obtained several fertile hybrid derivatives with FHB resistance. We isolated a disomic addition line (2 n = 28 + 2) with a pair of L. elongatum chromosomes. This alien addition line is meiotically regular and hence reproductively stable. The addition line is FHB-resistant with a mean infection of 6.5%, while the parental durum has 80% infection. Using various biochemical and molecular techniques — fluorescent genomic in situ hybridization (fl-GISH) and chromosome-specific markers — we have shown that the extra chromosome involved is 1E of L. elongatum . This is the first time that FHB resistance has been discovered on chromosome 1E.

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Thinopyrum ponticum is particularly a valuable source of genes for wheat improvement. A novel wheat-Th. ponticum addition line, 1–27, was identified using cytology, SSR, ESTSSR, EST-STS and PCR-based landmark unique gene (PLUG) markers in this study. Cytological studies showed that 1–27 contained 44 chromosomes and formed 22 bivalents at meiotic metaphase I. Genomic in situ hybridization (GISH) analysis indicated that two chromosomes from Th. ponticum had been introduced into 1–27 and that these two chromosomes could form a bivalent in wheat background. Such results demonstrated that 1–27 was a disomic addition line with 42 wheat chromosomes and a pair of Th. ponticum chromosomes. One SSR marker (BARC235), one EST-STS marker (MAG3284) and 8 PLUG markers (TNAC1210, TNAC1787, TNAC1803, TNAC1805, TNAC1806, TNAC1821, TNAC1867 and TNAC1957), which were all from wheat chromosome group 7, produced the specific band in Th. ponticum and 1–27, indicating that the introduced Th. ponticum chromosomes belonging to the group 7 of wheat. Sequence analysis on specific bands from Th. ponticum and 1–27 amplified using the PLUG marker TNAC1867 further confirmed this result. The 1–27 addition line was also observed to be high resistant to powdery mildew though it is not clear if the resistance of 1–27 inherited from Th. ponticum. This study provided some useful information for effective exploitation of the source of genetic variability in wheat breeding.

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