Cloning and Characterization of a Novel Hypersensitive-induced Reaction Gene from Wheat Infected by Stripe Rust Pathogen

The hypersensitive response is one of the most sophisticated and efficient forms of plant defence response against fighting pathogen infection; it involves the rapid death of plant cells at and around infection sites, together with the restriction of pathogen growth. Based on a differentially expressed transcribed derived fragment previously identified from the large-scale transcript profiling of adult-plant wheat resistant to stripe rust - which was highly similar to the barley HvHIR3 gene - a novel hypersensitive-induced reaction (HIR) gene from wheat infected by stripe rust pathogen, designated as TaHIR3, was identified using in silico cloning, combined with reverse transcriptase-polymerase chain reaction (RT-PCR) method. TaHIR3 was predicted to encode a 287-amino acid protein with a deduced molecular weight of 31.5 kDa and a pI of 5.68. An amino acid sequence analysis of TaHIR3 demonstrated the presence of the Stomatins, Prohibitin, Flotillins, HflK/C protein domain and prohibitin homologues. A phylogenetic analysis of 17 HIR genes from different plant species indicated that the wheat TaHIR3 gene was highly homologous to the barley HvHIR3 gene, at both the cDNA and deduced amino acid levels. Using a real-time quantitative RT-PCR, expression profiles of TaHIR3 in wheat leaves that had been infected with stripe rust fungus at the adult-plant (incompatible) and seedling (compatible) stages were analysed. The results revealed that at the adult-plant stage, TaHIR3 was significantly induced after inoculation, with the occurrence maximum induction at 48 h postinoculation (hpi). At the seedling stage, TaHIR3 was also up-regulated as early as 12 hpi. However, the transcript amount was relatively lower than that of the adult-plant stage.