TRANSFORMATION OF THE OOMYCETE SAPROLEGNIA-MONOICA TO HYGROMYCIN-B RESISTANCE

Saprolegnia monoica was stably transformed to hygromycin resistance us ing the plasmids pTH210 and pHAM34H containing a bacterial phosphotran sferase gene fused to regulatory sequences from genes of another Oomyc ete. Vectors pBT6, pCM54, used to transform higher fungi, yielded no s table transformants. DNA hybridizations indicated that transformation resulted from a single-copy integration of the transforming vector. De velopment of non-resistant subcultures from transformed colonies revea led that the transgene could become silent and was not uniformly expre ssed in the transformants.