Wheat is one of the most essential food sources in the world. However, there has been serious yield loss of wheat production due to stripe rust disease caused by the fungal pathogen Puccinia striiformis f. sp. tritici. The cost-effective and long-lasting defense to the disease can be achieved by generating genetically resistant crops against the disease forming pathogens. To accomplish this, first step is to acquire knowledge in the plant pathogen interactions of the crop and the pathogen of interests at the cellular and the molecular level. In this thesis research, PstHa2a5 candidate effector gene from Puccinia striiformis f. sp. tritici is investigated to identify its role and interaction between host factors in yellow rust infected Triticum aestivum L. The gene construct was engineered with FLAG-tag fusion at its N-terminus, and synthesized. This construct was cloned into pJL48-TRBO vector for an expression in Nicotiana benthamiana via agrobacterium-mediated gene transformation. The expressed protein structure with FLAG-tag was purified, and immunoprecipitated with one putative N. benthamiana interactor by immunoprecipitation experiments. This candidate interactor protein will be identified with Mass Spectroscopy. In addition to this, subcellular localization of the effector candidate was examined in N. benthamiana plant. This was achieved by cloning PstHa2a5 gene construct in pK7WGF2 gateway destination vector and localization is determined by GFP expression in N. benthamiana after agrobacterium-mediated gene transformation.