Comparative genomic in situ hybridization (cGISH) analysis on plant chromosomes revealed by labelled Arabidopsis DNA

A new approach for comparative cytogenetic banding analysis of plant chromo somes has been established. The comparative GISH (cGISH) technique is unive rsally applicable to various complex genomes of Monocotyledonae (Triticum a estivum, Agropyron elongatum, Secale cereale, Hordeum vulgare, Allium cepa, Muscari armenaticum and Lilium longiflorum) and Dicotyledonae (Vicia faba, Beta vulgaris, Arabidopsis thaliana). Labelled total genomic DNA of A. tha liana generates signals at conserved chromosome regions. The nucleolus orga nizing regions (NORs) containing the majority of tandemly repeated rDNA seq uences, N-band regions containing satellite DNA, conserved homologous seque nces at telomeres and additional chromosome-characteristic markers were det ected in heterologous FISH experiments. Multicolour FISH analysis with repe titive DNA probes simultaneously revealed the chromosome assignment of 56 c GISH signals in rye and 61 cGISH signals in barley. Further advantages of t his technique are: (1) the fast and straightforward preparation of the prob e; (2) the generation of signals with high intensity and reproducibility ev en without signal amplification; and (3) no requirement of species-specific sequences suitable for molecular karyotype analysis. Hybridization can be performed without competitive DNA. Signal detection without significant bac kground is possible under low stringency conditions. The universal applicat ion of this fast and simple one-step fluorescence banding technique for pla nt cytogenetic and plant genome evolution is discussed.