IDENTIFICATION OF HOMOEOLOGOUS CHROMOSOMES IN HEXAPLOID OAT (A-BYZANTINA CV KANOTA) USING MONOSOMICS AND RFLP ANALYSIS

The use of RFLP markers, together with a partial set of monosomics ava ilable in Avena byzantina cv Kanota, has enabled us to identify putati ve homoeologous chromosome sets in hexaploid Avena species (2n=6x=42, AACCDD). We first identified probes producing distinct three-band patt erns on Southern blots that possibly reflect orthologous loci of the t hree genomes present in the hexaploid. Using monosomic analysis, 51 di fferent restriction fragments that hybridized to 26 probes were locali zed to 12 different chromosomes for which monosomic stocks were availa ble. These DNA restriction fragments were localized to specific monoso mics using image analysis to quantify band intensity relative to other bands in the same lane. From these data, we have tentatively identifi ed two complete homoeologous sets of three chromosomes each and two pa rtial sets of two of the three chromosomes. The results indicate that RFLP dosage analysis is useful in the characterization of homoeologous chromosomes in hexaploid oat where nullisomics for many of the chromo somes are not available.