The Role of Ethylene in Pamp-Triggered Immunity in Fusarium Crown Rot (FCR) in Wheat
Abstract
Fusarium Crown Rot (FCR) is a destructive cereal crop disease caused by fungal pathogens Fusarium graminearum, F. pseudograminearum, F. crookwellense, F. avenaceum, and F. culmorum (Akinsanmi, Mitter, Simpfendorfer, Backhouse, & Chakraborty, 2004; Balmas, Burgess, & Summerell, 1995; Mudge et al., 2006). Fusarium spp. impact grain quantity and quality by both reducing plant growth and producing mycotoxin deoxynivalenol (DON), further contaminating the crop for human and livestock consumption. Here, we investigate the effects of chemically stimulating and inhibiting the ethylene pathway on FCR disease resistance as well as the direct effects of these chemicals on the pathogen. Disease resistance to FCR in susceptible wheat cultivar ‘Kennedy’ and partially resistant ‘Bobwhite’ was enhanced by stimulating the ethylene-signaling pathway with commercially available phytohormone regulator ethephon and ethylene biosynthetic precursor 1-aminocyclopropene-carboxylic acid (ACC). Conversely, inhibiting ethylene signaling with competitive inhibitor 1-methylcylopropene (1-MCP) resulted in loss of resistance in ‘Bobwhite’ and exacerbation of FCR symptoms in ‘Kennedy’. RNA-Seq analyses of both cultivars during FCR infection identifies fundamental differences between genetically resistant and susceptible cultivars as well as highlights the impact of ethylene signaling and biosynthesis on the transcriptome during chemically induced resistance or susceptibility. There are 100 DEGs consistently expressed across all resistant responses, demonstrating that there are shared genes accessible by stimulating the ethylene pathway for improved FCR. These DEGs include known classic PTI components as well as R genes, novel defense response genes, and drought tolerance genes. The findings of this research demonstrate that components for FCR disease resistance are present and accessible in both partially resistant and susceptible cultivars through the ethylene signaling pathway.
Degree
Ph.D.
Advisors
Mengiste, Purdue University.
Subject Area
Plant Pathology|Plant sciences|Molecular biology
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