Plant Genome IV Conference Plant Genome IV Conference
The recovery from oat (Avena sativa L.) x maize (Zea mays L.) crosses of novel plants with individual maize chromosomes added to a complete oat genome has provided source material for a number of research projects on the genetic, cytological and molecular characterization of maize chromosomes in oat. In this study an oat maize disomic addition line which possesses 21 pairs of oat chromosomes and one pair of maize chromosome 9 was used to construct a cosmid library. A mixture of highly repetitive maize-specific sequences were used as a multiprobe to isolate cosmid clones containing maize genomic DNA. Individual cosmid clones, or their subcloned fragments corresponding to high, middle or low copy number sequences, were then used as probes in hybridization to a blot panel of five different chromosome addition lines and parental maize and oat lines. Their hybridization patterns revealed that a number of the unique sequences from different clones hybridized specifically to DNA of chromosome 9 while most repeated sequences were dispersed throughout all maize chromosomes. No chimeric clones were found suggesting that no significant exchanges of genetic material had occurred between the maize addition chromosome and the oat genome. These data allow us to suggest the use of oat as a host for the cloning of large maize genomic DNA fragments. Breaking apart the maize chromosome by irradiation to yield lines with chromosome segments added to the oat genome will allow construction of a library of fragments of each individual maize chromosome in oat.