constitutively active RabG3b displayed expanded programmed cell death – hypersensitive response upon infection and accelerated leaf senescence. Their results suggest that RabG3b may regulate PCD associated with pathogen response and senescence. PCD-HR is one of numerous complicated defense responses that allow SP600125 129-56-6 plants to survive invasion by various infectious pathogens. Wheat stripe rust fungus, Pucinia striiformis f. sp. tritici, is one of the most devastating pathogens of wheat, causing significant yield loss in wheat production worldwide. One of the most effective methods to control stripe rust is the use of resistant wheat cultivars. Comprehending molecular mechanisms of interactions between wheat and the stripe rust pathogen is important to the rational use of resistance genes in the improvement of cultivars. Although the structure and function of Rab7 in trafficking has been studied, little is known about its function in the interaction between wheat and the stripe rust fungus. In this study, we isolated and characterized a wheat Rab7 homologue, designated TaRab7. The expression profile of TaRab7 was determined in wheat seedlings inoculated with Pst and plants subjected to environmental stimuli. Subcellular localization of TaRab7 was also determined to reveal its function in the interaction, and expression of TaRab7 in an incompatible wheat-Pst interaction was decreased by virus induced gene silencing, further indicating its important role in wheat defense against the rust pathogen. The amino acid sequence alignment demonstrated that TaRab7 has the conserved guanine nucleotide binding motifs and domains of small G proteins from animals and plants, which are important for interaction with its regulators and effectors. The phylogenetic analysis showed that TaRab7 has the highest similarity to small GTP binding protein OsRab7 in rice and to RabG3b in the Rab subfamily proteins in Arabidopsis. Based on previous research, the OsRab7 plays an important role in response to environmental stresses and AtRabG3b is vital for plant defense to pathogens. The high homology of TaRab7 to the rice and Arabidopsis genes let us to make a hypothesis that the wheat gene has the similar role in response to environmental stresses and pathogen infection. The serious experiments conducted in this study proved the hypothesis. Plant defense responses against microbial infection are often triggered during the initial stages of plant-pathogen interactions, and the early recognition and penetration between wheat and Pst occurred from 6 to 12 hpi. qRT-PCR was utilized to analyze the expression pattern of TaRab7 in wheat seedlings inoculated with Pst race CYR23 and CYR31. The results showed that, in the incompatible interaction, TaRab7 was up-regulated at 6 hpi and the expression remained at a high level, however, in the compatible interaction, TaRab7 was also about 4-fold higher than that in the control group at 6 hpi but it began to down-regulate since then.