Abstract

One concern for garlic (Allium sativum Linnaeus) producers is the damage caused by the pathogen Sclerotium cepivorum Berk. Unfortunately, the genetic and molecular mechanisms that participate during S. cepivorum Berk pathogenesis are currently unknown. In order to identify and isolate genes that are differentially expressed by the fungus during garlic white rot pathogenesis, PCR-based suppression subtractive hybridization (SSH) was used. Combining SSH and cDNA arrays hybridization techniques, 120 ESTs whose expression is restricted to the pathogenic stage were identified and isolated. Fourteen ESTs showing higher expression in cDNA arrays were sequenced, these included homologues to oxaloacetate acetylhydrolase (Oah), cysteine desulfurase (Nfs 1p), regulator of drug sensitivity (Rds 1p), outer membrane protein (Omp 1) and cell wall adhesion (Fig2p). One selected EST with high homology to Oah gene, a putative virulence factor, was analyzed by RT-PCR. The possible role of Oah gene in the pathogenesis of this fungus toward garlic is discussed. The combined applications of SSH and cDNA arrays permitted global analysis of gene expression patterns in S. cepivorum Berk, as an initial stage to improve the knowledge at molecular level from fungal pathogenesis.

Key words: Pathogenesis, differential gene expression, suppression subtractive hybridization, cDNA arrays, Oah gene.