Inactivation of transgenes in Phytophthora infestans is not associated with their deletion, methylation, or mutation.
The mitotic and meiotic stabilities of transgenes were evaluated in the oomycete, Phytophthora infestans. Genes encoding beta-glucuronidase (GUS), neomycin phosphotransferase (NPT) and hygromycin phosphotransferase (HPT), fused to one of six promoters from P. infestans or other oomycetes, were usually stably expressed during continued asexual culture and transmitted to progeny. However, the activity of these genes became undetectable in many strains during asexual or sexual propagation. Over 33 months of growth, transgene expression stopped each month in 1-3% of the transformants. Silencing of the genes was not associated with their deletion, mutation, or hypermethylation. The conformation of the integrated sequences was similar in strains destined to continue or terminate expression of the transgenes. Expression of the genes was not associated with a loss of fitness during growth in vitro and in planta, which might otherwise have selected for silencing events.
Judelson
H S
HS
Department of Plant Pathology, University of California, Riverside 92521, USA.
Whittaker
S L
SL
D001483:Base Sequence; D002455:Cell Division / Q000235:genetics; D017353:Gene Deletion; D015966:Gene Expression Regulation, Fungal; D005800:Genes, Fungal; D005819:Genetic Markers; D005966:Glucuronidase / Q000235:genetics; D017403:In Situ Hybridization; D019868:Kanamycin Kinase; D008540:Meiosis; D008745:Methylation; D008938:Mitosis; D008969:Molecular Sequence Data; D009154:Mutation; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000235:genetics; D010838:Phytophthora / Q000235:genetics*; D011401:Promoter Regions, Genetic; D012098:Reproduction; D012641:Selection, Genetic; D014170:Transformation, Genetic; D019076:Transgenes
D005819:Genetic Markers; D017853:Phosphotransferases (Alcohol Group Acceptor); C063242:hygromycin-B kinase; D019868:Kanamycin Kinase; D005966:Glucuronidase