MAPPING OF THE ADP-GLUCOSE PYROPHOSPHORYLASE GENES IN BARLEY

cDNA probes encoding the barley endosperm ADP-glucose pyrophosphorylas e (AGP) small subunit (bepsF2), large subunit (bep110), and leaf AGP l arge subunit (b1p1) were hybridized with barley genomic DNA blots to d etermine copy number and polymerphism. Probes showing polymorphism wer e mapped on a barley RFLP map. Probes that were not polymorphic were a ssigned to chromosome arms using wheat-barley telosomic addition lines . The data suggested the presence of a single-copy gene corresponding to each of the cDNA probes. In addition to the major bands, several we aker cross-hybridizing bands indicated the presence of other, related sequences. The weaker bands were specific to each probe and were not d ue to crosshybridization with the other probes examined here. The endo sperm AGP small subunit (bepsF2) major band locus was associated with chromosome 1P and designated Aga1. The endosperm AGP large subunit (be p110) major-band locus was mapped to chromosome 5M and designated Aga7 . The endosperm AGP large-subunit minor bands were not mapped. The lea f AGP large-subunit major band was associated with chromosome 7M and d esignated Aga5. One of the leaf AGP large-subunit minor bands was mapp ed to chromosome 5P and designated Aga6. A clone for the wheat endospe rm AGP large-subunit (pAga7) hybridized to the same barley genomic DNA bands as the corresponding barley probe indicating a high degree of i dentity between the two probes.