LI, CHANGBAO1,2*, DAMING ZHANG1, SONG GE1, DE-YUAN HONG1, and TAO SANG2. 1Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China; 2Department of Botany & Plant Pathology, Michigan State University, East Lansing, MI 48824. - Genomic in situ hybridization: A useful tool for understanding genome evolution of Oryza (Poaceae).
Molecular cytogenetics opens an avenue to address old questions of
biosystemtics and new questions of genome evolution. Genomic in situ
hybridization (GISH) was used to examine origins and evolution of the
allotetraploid genomes, BBCC and CCDD, of Oryza (Poaceae). The
results indicated that species of the BBCC genome contained two
clearly distinguishable diploid genomes of BB and CC. The CCDD genome,
which had a more ancient origin than the BBCC genome, has undergone
extensively DNA exchange between chromosomes of the two diploid
genomes. The dispersed hybridization signals consequently prevented
the detection of the allotetraploid origin of the CCDD genome using
GISH. The strength of GISH signals between various diploid genomes of
Oryza was often inconsistent with phylogeny or sequence
divergence of single-copy nuclear genes. This raises an important
question concerning genomic and evolutionary interpretation of GISH
results.
Key words: allopolyploid, genome evolution, GISH, Oryza