<p><i>Puccinia striiformis f.sp tritici</i> (Pst) causes major losses in the global production of wheat by causing Yellow Stripe Rust Disease (YSRD). YSRD proceeds through an interaction that takes place between the Pst effector proteins and wheat’s immune-related proteins. PST_8713 is an important effector employed by Pst that has been shown to interact with the pathogenesis-related (PR) immune proteins in the model plant <i>N. benthamiana</i>. There was a need to study this interaction in wheat which is the actual host of Pst. Hence, the present study aimed to develop this understanding through a constructed <i>in-silico</i> structural model of the PST_8713 effector which was docked with the wheat homologues of PR proteins. This interaction study helped in identification of residues of PST_8713 that potentially form contacts with the wheat PR proteins. Moreover, PST_8713 has been reported to show a low level of intra-specific sequence polymorphism. To explore the variation in the effector, the infected leaf samples were collected from various locations in Sindh, Pakistan. PCR amplification of partial coding sequences of PST_8713 was carried out using our designed primers. However, the results showed the presence of a novel point mutation of a heterozygous nature in around 8% of the disease samples collected. The mutation results in the substitution of cysteine in place of asparagine at position 72 of the PST_8713 effector protein. To the best of our knowledge, the identified mutation has not been previously reported. Our results suggest that PST_8713 is an important effector which is in the process of selection through mutation.</p>