Chemical Activation of the Ethylene Signaling Pathway Promotes Fusarium graminearum Resistance in Detached Wheat Heads

Citation

Foroud, N.A., Pordel, R., Goyal, R.K., Ryabova, D., Eranthodi, A., Chatterton, S., Kovalchuk, I. (2019). Chemical Activation of the Ethylene Signaling Pathway Promotes Fusarium graminearum Resistance in Detached Wheat Heads, 109(5), 796–803. http://dx.doi.org/10.1094/PHYTO-08-18-0286-R

Plain language summary

Fusarium head blight (FHB) is a fungal disease of wheat and related cereal crops, commonly known as scab. The fungal species responsible produce mycotoxins, such as deoxynivalenol (DON; also known as vomitoxin), that accumulate in kernels of infected plants. The toxins cause extensive damage to developing kernels and render them unsuited to human and animal consumption. FHB resistance is a key factor in successful disease management practices. Resistance is mediated in part through the activities of plant hormones. The role of ethylene, a gaseous plant hormone, in the FHB disease response is poorly understood. Using different ethylene enhancer and inhibitor treatments, we found that ethylene signalling can mediate FHB resistance. Future directions for this work are to understand the interaction of this hormone pathway with other plant hormones and to (a) determine whether viable treatments can be developed to assist farmers in handling this disease, and (b) develop markers to breed for resistance cultivars.

Abstract

Plant signaling hormones such as ethylene have been shown to affect the host response to various pathogens. Often, the resistance responses to necrotrophic fungi are mediated through synergistic interactions of ethylene (ET) with the jasmonate signaling pathway. On the other hand, ET is also an inducer of senescence and cell death, which could be beneficial for some invading necrotrophic pathogens. Fusarium graminearum, a causative agent in Fusarium head blight of wheat, is a hemibiotrophic pathogen, meaning it has both biotrophic and necrotrophic phases during the course of infection. However, the role of ET signaling in the host response to Fusarium spp. is unclear; some studies indicate that ET mediates resistance, while others have shown that it is associated with susceptibility. These discrepancies could be related to various aspects of different experimental designs, and suggest that the role of ET signaling in the host response to FHB is potentially dependent on interactions with some undetermined factors. To investigate whether wheat genotype can influence the ET-mediated response to FHB, the effect of chemical treatments affecting the ET pathway was studied in six wheat genotypes in detached-head assays. ET-inhibitor treatments broke down resistance to both initial infection and disease spread in three resistant wheat genotypes, whereas ET-enhancer treatments resulted in reduced susceptibility in three susceptible genotypes. The results presented here show that the ET signaling can mediate FHB resistance to F. graminearum in different wheat backgrounds.