Plant C2 domain proteins play important roles in diverse cellular processes including growth, development, and membrane targeting, as well as in abiotic and biotic stress adaptations by sensing intracellular Ca 2+ signals. In this study, we isolated a novel C2 domain protein gene, TaERG3, from wheat infected by Puccinia striiformis f. sp. tritici. TaERG3 was predicted to encode a 144 amino acid protein with molecular mass of 15.68 kD and isoelectric point of 3.93. Analysis of the deduced amino acid sequence of TaERG3 using InterProScan revealed the presence of an N-terminal calciumdependent phospholipid-binding module (C2 domain, 5 to 103). Transient expression analysis showed that the TaERG3 protein was predominately and uniformly localized in the plasmalemma and nucleus of onion epidermal cells. Quantitative real-time PCR analyses indicated that TaERG3 transcript was differentially induced in both incompatible and compatible interactions, as well as by applied abscisic acid (ABA) and CaCl 2 . However, the significant transcript changes induced by methyl jasmonate, ethylene, and salicylic acid treatments were not as dramatic as those induced by ABA. TaERG3 was also up-regulated by environmental stimuli including low temperature and high salinity. These results imply that TaERG3 might be involved in wheat defence responses against stripe rust and abiotic stresses in an ABA-dependent signalling pathway.

A novel gene induced during hypersensitive reaction (HIR) in wheat was identified using in silico cloning and designated as TaHIR2. The TaHIR2 gene was deduced to encode a 284-amino acid protein, whose molecular mass and isoelectric point (pI) were 31.05 kD and 5.18, respectively. Amino acid sequence analysis demonstrated the presence of stomatins, prohibitin, flotillins, HflK/C (SPFH) domain and prohibitin homologue for the TaHIR2 protein. Phylogenetic analysis of 13 HIR genes from different monocots indicated that TaHIR2 was highly homologous to HvHIR2. Transient expression analysis using particle-mediated bombardment showed that the TaHIR2 fusion protein was located in the onion epidermal cells. Quantitative RT-PCR analyses revealed that TaHIR2 transcripts were significantly accumulated in adult wheat leaves with maximum induction at 18 h post inoculation with the stripe rust, whereas slightly up-regulation could also be observed in the compatible reaction at the seedling stage. These results suggest that TaHIR2 may play an active role in wheat defense against stripe rust.