Characterization of New Wheat- Thinopyrum intermedium Derivative Lines with Superior Genes for Stripe Rust and Powdery Mildew Resistance.

The wild species Thinopyrum intermedium (genome JJJ S J S StSt) serves as a valuable germplasm resource providing novel diseases resistance and agronomically important genes for wheat improvement. Two wheat- Th. intermedium partial amphiploids, TAI7045 (2n = 56) and 78784 (2n = 56), exhibit high resistance to stripe rust and powdery mildew, and their chromosome constitutions have been characterized. With the aim to transfer novel resistance genes from Th. intermedium , the crosses of common wheat line MY11 with TAI7045 and 78784 were produced, and their individual F 2 -F 5 progenies were characterized using sequential non-denaturing fluorescence in situ hybridization (ND-FISH) and molecular markers. We identified a set of wheat- Th. intermedium addition lines, involving the chromosomes 1St-J S , 2St, 2St-J S , 3St, 4J, 4St, 5St, 5J.St, 6J S .J, and 7J S . Above all, the stable wheat- Th. intermedium small segmental translocation lines with chromosomes 4DS.4DL-4StL-4DL-4JL and 4DS.4DL-4StL-4DL were selected. Combining data from specific marker amplification and resistance evaluation, we mapped the gene(s) for resistance to powdery mildew and stripe rust in the 233.56-329.88 Mb region of the long arm of the 4St chromosome from the reference Th. intermedium genome. The new wheat- Th. intermedium introgressions will be used as novel germplasm for breeding purposes.