Identification and analysis of in planta expressed genes of Magnaporthe oryzae.
BACKGROUND
Infection of plants by pathogens and the subsequent disease development involves substantial changes in the biochemistry and physiology of both partners. Analysis of genes that are expressed during these interactions represents a powerful strategy to obtain insights into the molecular events underlying these changes. We have employed expressed sequence tag (EST) analysis to identify rice genes involved in defense responses against infection by the blast fungus Magnaporthe oryzae and fungal genes involved in infectious growth within the host during a compatible interaction.


RESULTS
A cDNA library was constructed with RNA from rice leaves (Oryza sativa cv. Hwacheong) infected with M. oryzae strain KJ201. To enrich for fungal genes, subtraction library using PCR-based suppression subtractive hybridization was constructed with RNA from infected rice leaves as a tester and that from uninfected rice leaves as the driver. A total of 4,148 clones from two libraries were sequenced to generate 2,302 non-redundant ESTs. Of these, 712 and 1,562 ESTs could be identified to encode fungal and rice genes, respectively. To predict gene function, Gene Ontology (GO) analysis was applied, with 31% and 32% of rice and fungal ESTs being assigned to GO terms, respectively. One hundred uniESTs were found to be specific to fungal infection EST. More than 80 full-length fungal cDNA sequences were used to validate ab initio annotated gene model of M. oryzae genome sequence.


CONCLUSIONS
This study shows the power of ESTs to refine genome annotation and functional characterization. Results of this work have advanced our understanding of the molecular mechanisms underpinning fungal-plant interactions and formed the basis for new hypothesis.
Department of Agricultural Biotechnology, Center for Fungal Pathogenesis, Center for Agricultural Biomaterials and Center for Fungal Genetic Resources, Seoul National University, Seoul 151-921, Korea.
Soonok
S
Kim
Jongsun
J
Park
Sook-Young
SY
Park
Thomas K
TK
Mitchell
Yong-Hwan
YH
Lee
D019295:Computational Biology; D004271:DNA, Fungal / Q000235:genetics; D018744:DNA, Plant / Q000235:genetics; D020224:Expressed Sequence Tags; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D015723:Gene Library; D005800:Genes, Fungal; D017343:Genes, Plant; D016681:Genome, Fungal; D020082:Magnaporthe / Q000235:genetics*; D008957:Models, Genetic; D012275:Oryza / Q000235:genetics* / Q000382:microbiology; D010935:Plant Diseases / Q000382:microbiology; D017422:Sequence Analysis, DNA
D004271:DNA, Fungal; D018744:DNA, Plant