Journal of Taiwan Agricultural Research

Author:Hsiu-Ying Lu*, Yi-Chia Chiu, Cheng-Tao Chen, Meng-Li Wei and Chun-Tang Lu

Abstract:

    Rice blast is caused by fungus pathogen Magnaporthe grisea, which is a major destructive disease in rice production worldwide. Expressed sequence tag (EST) is the fragment of cDNA sequence. Direct study of EST is therefore helpful to obtain the gene expression information. In order to investigate the differences of gene expression patterns of rice among varieties, tissues and developmental stages after rice-blast infection, we made a comparative analysis of rice ESTs induced by M. grisea from 14 cDNA libraries in NCBI-dbEST database. For each individual library, EST functional annotation, classification and representation statistics were performed. Clustering analysis and correspondence analysis were also used to detect the differences in gene expression patterns among libraries and identify the functional categories involved. Results showed that wild rice infected by M. grisea exhibited more transcripts involved in metabolism, cell growth / morphogenesis, subcellular localization and transport facilitation compared to indica rice and japonica rice. The representation of genes associated with metabolism and energy functions in infected rice leaf at mature stage was highest, followed by tillering stage, seedling stage. When rice ESTs induced by M. grisea were mixtures of sequences with different rice varieties and tissues, it appeared diversity of gene expression from those of rice ESTs from single source. These findings will facilitate understanding of the resistance mechanisms against rice blast.

Key words:Rice, Rice blast, Expressed sequence tag, Functional annotation and classification, Statistics of gene representation, Clustering analysis, Correspondence analysis

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