| Species of Thinopyrum, including Th. intermedium, Th. elongatum and Th. Ponticum, posses a number of elite agronomic traits, and thus all of the three have been the most important perennial Triticeae germplasm sources for further wheat improvement. Chromosome 7E of Thinopyrum is crucial because it is the carrier of a number of genes including fusarium resistance, leaf rust resistance, stem rust resistance, and yellow dwarf virus resistance. In the present study, their homeologous relationship among different Thinopyrum chromosome 7E were identified and analyzed by methods of morphology, cytology and molecular biology. The main results were as follows:(1) Genomic in situ hybridization (GISH) was used to establish the genomic origins of the 4 alien chromosomes in substituted lines. Two substituted lines, P29 and K11463, had a pair of J-genome chromosomes. A pair of St chromosomes were detected in K2620. A pair of Ea chromosomes substituted a pair of wheat chromosomes in 7E/7D derived from Th. elongatum.(2) The segregation ratio of 64 molecular markers was investigated on the Th.ponticum chromosome 7E. Among them, 44 showed significant segregation distortion (P<0.05), and the preferential segregation pattern was in favor of chromosome K2620, which was derived from the male parent K2620. The distorted markers on the map of chromosome 7E were clustered as segregation distortion regions (SDR). However, such a segregation distortion pattern was not observed within the regions harboring the Lr19 and FhbLoP genes, suggesting that these closely-linked markers could be valuable for marker-assisted introgression of elite genes into our existing wheat cultivars.(3) Meiotic paring was also studied in 3 hybrid progenies. Since pairing between P29 with K2620 and 7E/7D chromosomes was generally low, it is suggested that the chromsomes are not closely related. By methods of GISH and cytology, K2620 and 7E/7D chromosomes are related homeologously.
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