Unraveling transcriptional regulatory mechanisms involved in sexual
reproduction of Phytophthora infestans
Xiaofan Niu, Warapon Prakob, and Howard Judelson
Phytophthora infestans, the causal agent of potato and tomato late blight, is one of the most
devastating plant pathogens in the world.
The sexual reproduction cycle of P. infestans
serves an important role in disease since the sexual spores (oospores) are important for
survival over the long-term and through unfavorable conditions.
In order to understand the
mechanisms of sexual development, microarray analyses were performed that identified 87
genes induced or up-regulated more than 10-fold during the process.
Ten genes that are
expressed specifically during mating, or up-regulated more than 100-fold, were selected for
detailed analysis, including characterizing functional regions within their promoters..
Promoters have been fused with the GUS reporter gene, and transformed into P. infestans to
examine their temporal and spatial expression patterns. The promoter of gene Pi000192,
which is predicted to encode an elicitin-like protein, has shown specific activity in oogonia and
antheridia.
Deletions of this region are now being tested to help define its regulatory
elements. Site-directed mutagenesis and electrophoretic mobility gel shift assays will be used
to confirm the presence of such cis-elements. These regulatory domains will be used to
identify the transcription factors that are involved in sexual development.
Other potential
regulators of gene expression, such as a RNA binding protein made during sexual
development, are also being studied.
Department of Plant Pathology and Microbiology, University of California, Riverside, CA 92521 USA