Identification of elicitor-induced PR5 gene homologue in Piper colubrinum Link by suppression subtractive hybridization

摘要

Piper colubrinum Link., the exotic wild Piper shows high degree of resistance to fungal pathogens and is a potential source of resistance genes. A PCR-based suppression subtractive hybridization (SSH) was used to identify P. colubrinum genes that are differentially expressed in response to the signalling molecule, salicylic acid (SA). A subtracted library of SA-induced genes was synthesized and one of the clones showed sequence homology to osmotin, a member of class-V group of pathogenesis- related (PR) gene family. The 315 bp gene fragment was used to probe total RNA prepared from untreated and SA-treated leaf tissues. Osmotin fragment cloned from the subtracted library was also used to probe RNA from ethylene-treated leaf tissues. Northern blot analysis revealed that osmotin is dominantly expressed in SA/ethylene-treated tissue. This indicates that SSH can be used to identify and clone PR genes in P. colubrinum.