Abstract: 【Objective】 The objective of the paper is to investigate if the heterotrimeric G protein is involved in the defense responses of wheat to Puccinia triticina. 【Method】 After 24h of treating the detached-leaf with the regulators of heterotrimeric G protein (activator and inhibitor), the infection types at the 9th day were evaluated by inoculating Puccinia triticina. The activities of defensive enzymes POD (peroxidase), PAL (phenylalanine ammonia lyase), and PPO (polyphenoloxidase) were tested after the leaves induced by the regulators of heterotrimeric G protein. In addition, the expression of the heterotrimeric G protein α subunit gene was evaluated by semi-quantitative RT-PCR after inoculating the virulent race and avirulent race, respectively. 【Result】 The activators delayed the disease occurrence, however the inhibtor had no effect on the development of wheat leaf rust. The activity of defensive enzymes was enhanced after treating with activators GTPγS and Mastoparan-7. Inhibitor PTX (pertussis toxin) inhibited the enhancement of defensive enzymes induced by the avirulent race. The avirulent race enhanced the expresstion of the heterotrimeric G protein α subunit gene, but virulent race inhibited its expression. 【Conclusion】 The results suggest that G protein may play a role in the resistance to Puccinia triticina.

Key words: wheat leaf rust, heterotrimeric G protein, defensive response