Characterization of the expression profile of a wheat aci-reductone-dioxygenase-like gene in response to stripe rust pathogen infection and abiotic stresses

The methionine salvage pathway is conserved from prokaryotes to high eukaryotes. The reaction catalyzed by aci-reductone-dioxygenase (ARD) represents a branch point in the methionine salvage pathway. A novel aci-reductone-dioxygenase gene, designed as TaARD, was identified in a subtraction library constructed with RNA isolated from wheat leaves infected with the stripe rust pathogen. TaARD was predicted to encode a 197 amino acid protein that belongs to the cupin superfamily. In transient expression assays with onion epidermal cells, the TaARD-GFP fusion protein localized to the nucleus and cytoplasm. Southern blot analysis showed that the wheat genome had multiple copies of TaARD. Quantitative real-time RT-PCR (qRT-PCR) analyses revealed that the TaARD transcript was induced in wheat leaves infected with a compatible stripe rust strain. However, its expression was reduced or suppressed in incompatible interactions and by ABA, ethephon (ET), or salicylic acid (SA) treatments. With methyl jasmonate (MeJA) treatment, TaARD transcript level was suppressed in the first 6 h but increased afterwards. The expression of TaARD also was inhibited by wounding and environmental stimuli, including high salinity and low temperature. Because of the role of ARD in the methionine salvage pathway, these results suggest that TaARD may be involved in ethylene synthesis and ethylene signaling in response to biotic and abiotic stresses.