Poster

Mercy Mormor ¹, Md. Ashraful Islam ¹, Steven Scofield ² and Jyoti Shah ¹
1. Department of Biological Sciences and BioDiscovery Institute, University of North Texas, Denton, TX, 76201, USA
2. USDA-ARS, West Lafayette IN, 47907, USA
Corresponding Author: Jyoti Shah, jyoti.shah@unt.edu

Mormor, Mercy

MercyMormor@my.unt.edu

Fusarium head blight (FHB), primarily caused by Fusarium graminearum, is a major disease of wheat that reduces yield and grain quality. FHB is associated with contamination by mycotoxins such as deoxynivalenol (DON), which threaten food safety and agricultural sustainability. Plants defense mechanisms against fungal pathogens are regulated by intricate signaling pathways such as the salicylic acid (SA)-mediated systemic acquired resistance (SAR) pathway. Central to the pathway is the Nonexpressor of Pathogenesis-Related genes (NPR) family, particularly NPR1, a transcriptional coactivator and positive regulator of SA-dependent defense gene expression and NPR3, a negative regulator of SA signaling and mediator for NPR1 degradation via the CUL3a E3 Ubiquitin Ligase complex to regulate immune homeostasis in response to fluctuating salicylic acid (SA) levels (Khan et al., 2020). Recent studies suggest that fungal pathogens produce factors, including deubiquitinases, that suppress host immunity by targeting defense-related signaling pathways (Lo Presti et al., 2015; de Jonge et al., 2011). Deubiquitinases (DUBs) are important regulators of ubiquitin-mediated protein turnover and cellular signaling but whether the fungal DUBs deubiquitinate NPR3 to stabilize it and thus facilitate NPR1 degradation has not been tested. Recent findings from our lab show that compared to the wheat cv Bobwhite, some fungal DUBs are expressed at negligible levels in the comparatively more FHB resistant wheat Lpx3-RNAi line in which expression of a 9-lipoxygenase is knocked down. This study investigates the impact of these Fusarium graminearum DUBs on NPR1 and NPR3 protein stability and function in wheat defense.

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