The ipiO gene of Phytophthora infestans is highly expressed in invading hyphae during infection.
The expression of the in planta-induced gene ipiO of the potato late blight pathogen Phytophthora infestans was analyzed during various developmental stages of its life cycle. ipiO mRNA was detected in zoospores, cysts, germinating cysts, and young mycelia, but not in sporangia or in old mycelia grown in vitro. ipiO is not only expressed in stages prior to infection but also during colonization of potato and tomato leaves. In disease lesions, ipiO mRNA was detected in the water-soaked area and the healthy-looking plant tissue surrounding it. In contrast, ipiO mRNA was not found in necrotized tissue or in sporulating areas of a lesion. To determine more precisely the location and time of ipiO gene expression in planta, cytological assays were performed using a P. infestans transformant expressing a transcriptional fusion between the ipiO1 promoter and the beta-glucuronidase (GUS) reporter gene. GUS staining was found specifically in the subapical and vacuolated area of tips of invading hyphae. The histochemical GUS assays demonstrate that ipiO is expressed during biotrophic stages of the disease cycle.
van West
P
P
Department of Phytopathology and Department of Plant Cytology and Morphology, Wageningen, The Netherlands.
de Jong
A J
AJ
Judelson
H S
HS
Emons
A M
AM
Govers
F
F
D015152:Blotting, Northern; D015139:Blotting, Southern; D005656:Fungal Proteins / Q000235:genetics*; D015870:Gene Expression; D005800:Genes, Fungal; D017930:Genes, Reporter; D005966:Glucuronidase / Q000235:genetics / Q000378:metabolism; D006651:Histocytochemistry; D018551:Solanum lycopersicum / Q000382:microbiology*; D010838:Phytophthora / Q000235:genetics* / Q000254:growth & development; D010935:Plant Diseases / Q000382:microbiology; D018515:Plant Leaves / Q000382:microbiology; D011401:Promoter Regions, Genetic; D012331:RNA, Fungal / Q000032:analysis; D011198:Solanum tuberosum / Q000382:microbiology*; D013172:Spores, Fungal / Q000235:genetics; D014170:Transformation, Genetic
D005656:Fungal Proteins; C112546:IpiO1 protein, Phytophthora infestans; D012331:RNA, Fungal; D005966:Glucuronidase