Genomic and Phylogenetic Relationships among Rye and Perennial Species in the Triticeae1

Abstract

Genomic and phylogenetic relationships among rye (Secale cereale L.) and eight perennial species representing the genera Pseudoroegneria, Thinopyrum, and Elymus were analyzed by in situ hybridization with two repeated DNA sequence probes from rye. The 120‐base pair (bp) sequence was observed to be present in all the perennial species, but only Thinopyrum elongatum showed an in situ hybridization pattern similar to that of rye. In both species, the 120‐bp sequence was distributed throughout the entire length of all seven pairs of chromosomes. The other species showed weak labeling or few sites of hybridization with the 120‐bp sequence. The 480‐bp sequence, which is specific to S. cereale, was detected in eight pairs of chromosomes of Thinopyrum intermedium and in one pair of chromosomes of Elymus trachycaulus. The labeled chromosomes in the hexaploid T. intermedium may have consisted of chromosomes from the ✕ genome, whose origin is unknown and is distinctly different from the two related genomes present in this species. This is the first report on the occurrence of the 480‐bp sequence (in the ✕ genome of T. intermedium) outside of the genus Secale and may indicate either a phylogenetic relationship or an independent amplification event. The results of the 120‐bp sequence confirm the widespread occurrence of this sequence in the Triticeae tribe. Both sequences provide valuable markers for molecular cytology (e.g., 120‐bp sequence for E genome and 480‐bp sequence for ✕ genome) for use in controlled introgression of useful traits from species containing these genomes into wheat.