Hybrid Origin of × Leymotrigia bergrothii (Poaceae) as Revealed by Analysis of the Internal Transcribed Spacer ITS1 and trn L Sequences

× is a presumed hybrid of and . This article investigates the hybrid origin and genome composition of this species. These plants are sterile, do not undergo pollination, and do not produce seeds; occasionally, underdeveloped stamens containing abortive pollen grains form in individual spikelets. The karyotype analysis of root meristem cells revealed a diploid chromosome number of 49 in × , reported here for the first time. Subsequently, we examined the intragenomic polymorphism of the transcribed spacer ITS1 in several species of , , , , and , and compared the ribotype patterns of these species with those of × It is shown that the St-ribotype variants found in and , as well as the ribotypes of the La family, which dominate in the genome of , correspond to major ribotypes in × . The ribotypes of the St and La families are present in the nuclear genome of × in almost equal proportions. A comparison of intron and exon sequences of the L gene in the chloroplast DNA of ey , , and × showed that this region in × is identical or very close to that of , suggesting that was the cytoplasmic donor to × Thus, our study confirms the hypothesis that this species represents a sterile first-generation hybrid of and , reproducing vegetatively.