cDNA-AFLP analysis reveals that maize resistance to Bipolaris maydis is associated with the induction of multiple defense-related genes

The fungal pathogen Bipolaris maydis invades by direct penetration into mai ze leaf veins. In order to understand the resistance mechanism of maize to A maydis strain 523, cDNA-AFLP (amplified fragment length polymorphism) ana lysis was conducted to compare the changes in mRNA transcripts in response to B. maydis infection between a highly disease-resistant (HDR) line and a susceptible (S) line. 13 cDNA fragments derived from the genes showing enha nced expression after fungal infection, named HDR genes, were isolated from the HDR line. Northern blot analysis showed that 5 HDR genes were induced by fungal infection in the HDR, but not the S lines. The 5 HDR genes showed homology to previously characterized genes involved in disease resistance. A full-length HDR10 cDNA was isolated. It had a capacity to encode a prote in of 284 amino acids. The deduced amino acid sequence of the HDR10 gene wa s homologous to a fungal infection-induced protein from Cicer arietinum and a hypersensitive response protein from maize, respectively. These results suggest that maize resistance to B. maydis infection in the HDR line may be mediated by the induction of multiple defense-related genes.