Isolation of resistance related-genes to Phytophthora infestans with suppression subtractive hybridization in the R-gene-free potato.

Suppression subtractive hybridization (SSH) was applied in the search of the genes induced during the interaction between Phytophthora infestans and horizontal resistance potato (R-gene-free). A subtractive library of potato, which highly enriches for resistance-related genes to P. infestans, was constructed. The potato leaves after inoculating 48 h with mixture of P. infestans races were used as "tester" and uninoculated leaves as "control" in the experiments. Total 150 of 840 randomly chosen cDNA clones were identified with the reveres Northern dot-blot screening method. The sequencing results of 26 clones indicated that several fragments were previously shown to be activated during resistance responses. Seven differentially expressed fragments had significant homologous with EST of potato leaves inoculated with P. infestans. The sequences of nucleotide or amino acids of partial cDNA fragments shared identity with tomato, tobacco and Arabidopsis while four cDNA fragments that had no significant homology with EST in GenBank were expected to be new genes involved in the disease response.