Submitted to: Chromosome Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/6/2003
Publication Date: 10/9/2003
Citation: Kishii, M, R. R.-C. Wang, and H. Tsujimoto. 2003. Characteristics and behavior of the chromosomes of Leymus mollis and L. racemosus (Triticeae, Poaceae) during mitosis and meiosis. Chromosome Research 11: 741-748. CHRO-864 Interpretive Summary: Species in the genus Leymus are all polyploids. The nature of polyploidy of these species is in question with studies using different techniques of genome analysis yielding contradictory evidence. To understand the reason for this discrepancy, we studied L. mollis and L. racemosus and their hybrids using both meiotic pairing and in situ hybridization techniques. Results revealed that these two species have diverged genomes with differences in repetitive DNA sequences that could be differentiated by GISH. Yet the chromosomes of these genomes are able to undergo complete meiotic pairing. Therefore, these DNA sequences are not affecting meiotic chromosome pairing. Studies using molecular techniques most likely lead to different conclusions from those derived from studies of meiotic pairing. An acceptable way to consolidate all data for correct interpretation will be needed.
Technical Abstract: Leymus mollis and L. racemosus (Triticeae; Poaceae) are important as genetic resources for wheat improvement, as they carry genes for salt tolerance and disease resistance. Even though these species share common Ns and Xm genomes, the genome relationship between these two species is not yet clearly understood. In this study, we examined the genomes of the two species by FISH and GISH, using combinations of tandem-repetitive sequences and genomic DNAs. Comparative GISH showed that genomes in the genus Leymus were diverse. Nevertheless, chromosomes of these two species were able to undergo complete meiotic pairing in hybrids, suggesting that differences in the subtelomeric heterochromatin and sequences distinguishable by GISH do not affect meiotic pairing.