MOLECULAR MARKER ANALYSIS OF HYPOPLOID REGENERANTS FROM CULTURES OF BARLEY X CANADA WILD RYE

Canada wild rye (CWR, Elymus canadensis L., 2n = 4x = 28) is a potenti al source of genes for disease resistance and environmental tolerance in barley (Hordeum vulgare L., 2n = 2x = 14). Tissue cultures were ini tiated from immature inflorescences of CWR x 'Betzes' barley hybrids t o promote CWR introgression into barley through possible tissue cultur e induced chromosome breakage and exchange. Among the plants regenerat ed, some were missing one (2n = 20) or part of one (2n = 20 + telo) ch romosome. The objective of this study was to identify the missing chro mosome or chromosome arm in these regenerants through the analysis of molecular (RFLP) markers that previously had been mapped in barley. Fo rty-six hypoploid regenerants that traced to 30 separate explants obta ined from 10 interspecific hybrid plants were evaluated. DNA was diges ted with the restriction enzyme HindIII, Southern blotted, and probed with 39 genomic and cDNA barley clones that identified sequences polym orphic between barley and CWR. Eight of these probes identified band l oss patterns that separated the regenerants into two groups. One group , all with barley cytoplasm, were missing a CWR chromosome homoeologou s to barley chromosome 3; a second group, all with CWR cytoplasm, were missing a CWR chromosome homoelogous to barley chromosome 7. These re sults indicated that chromosome elimination in culture was not random. The two cytoplasm groups were further differentiated by probes that i dentified band shifts. These band shifts were caused by differences in DNA methylation.