Anther culture of wheat (Triticum aestivum L.) F1's and their reciprocal crosses.

Anthers from three sets of wheat (Triticum aestivum L. em. Thell) F1's and their reciprocal crosses, made between parental lines differing greatly in their ability to produce microspore derived callus, were cultured on the Chinese potato medium so that we could 1) more clearly define the role of nuclear or cytoplasmic factors within T. aestivum in transferring the ability to undergo in vitro androgenesis, and 2) to briefly review the gametic representation and disease screening potential of the resulting polyhaploid wheat plants. The microspore derived calli values from F1's were slightly less than the midparental value. Statistical analysis indicated that the ability of each F1 to produce callus either did not significantly differ from that of the respective parental line having the highest androgenic yield or it exceeded its respective parental line having the lowest yield. No differences were noted between the members of each pair of reciprocal crosses. The results indicate that the transfer of in vitro androgenic ability to F1 hybrids is not dependent upon the maternal cytoplasm source. Polyhaploid plants, carrying the Pm 3 a powdery mildew resistance gene, expressed resistance to culture 4 a of powdery mildew.

Structure and function of selectable and non-selectable transgenes in maize after introduction by particle bombardment.

Zea mays transformants produced by particle bombardment of embryogenic suspension culture cells of the genotype A188 x B73 and selected on kanamycin or bialaphos were characterized with respect to transgene integration, expression, and inheritance. Selection on bialaphos, mediated by the bar or pat genes, was more efficient than selection on kanamycin, mediated by the nptII gene. Most transformants contained multicopy, single locus, transgene insertion events. A transgene expression cassette was more likely to be rearranged if expression of that gene was not selected for during callus growth. Not all plants regenerated from calli representing single transformation events expressed the transgenes, and a non-selectable gene (uidA) was expressed in fewer plants than was the selectable transgene. Mendelian inheritance of transgenes consistent with transgene insertion at a single locus was observed for approximately two thirds of the transformants assessed. Transgene expression was typically, but not always, predictable in progeny plants--transgene silencing, as well as poor transgene transmission to progeny was observed in some plant lines in which the parent plants had expressed the transgene.