Browsing by Author "Zerihun, A"

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    Spatiotemporal patterns of wheat response to Pyrenophora tritici-repentis in asymptomatic regions revealed by transcriptomic and x-ray fluorescence microscopy analyses
    (Oxford University Press (OUP), 2023-08-17) Moolhuijzen, P; Sanglard, LMVP; Paterson, DJ; Gray, SA; Khambatta, K; Hackett, MJ; Zerihun, A; Gibberd, MR; Naim, F
    Pathogen attacks elicit dynamic and widespread molecular responses in plants. While our understanding of plant responses has advanced considerably, little is known of the molecular responses in the asymptomatic ‘green’ regions adjoining lesions. Here, we explore gene expression data and high-resolution elemental imaging to report the spatiotemporal changes in the asymptomatic green region of susceptible and moderately resistant wheat cultivars infected with a necrotrophic fungal pathogen, Pyrenophora tritici-repentis. We show, with improved spatiotemporal resolution, that calcium oscillations are modified in the susceptible cultivar, resulting in ‘frozen’ host defence signals at the mature disease stage, and silencing of the host’s recognition and defence mechanisms that would otherwise protect it from further attacks. In contrast, calcium accumulation and a heightened defence response were observed in the moderately resistant cultivar in the later stage of disease development. Furthermore, in the susceptible interaction, the asymptomatic green region was unable to recover after disease disruption. Our targeted sampling technique also enabled detection of eight previously predicted proteinaceous effectors in addition to the known ToxA effector. Collectively, our results highlight the benefits of spatially resolved molecular analysis and nutrient mapping to provide high-resolution spatiotemporal snapshots of host–pathogen interactions, paving the way for disentangling complex disease interactions in plants. © The Author(s) 2023. Published by Oxford University Press on behalf of the Society for Experimental Biology. This is an Open Access article distributed under the terms of the Creative Commons Attribution License.
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    Synchrotron x-ray fluorescence microscopy-enabled elemental mapping illuminates the ‘battle for nutrients’ between plant and pathogen
    (Oxford University Press, 2021-03-29) Naim, F; Khambatta, K; Sanglard, LMVP; Sauzier, G; Reinhardt, J; Paterson, DJ; Zerihun, A; Hackett, MJ; Gibberd, MR
    Metal homeostasis is integral to normal plant growth and development. During plant–pathogen interactions, the host and pathogen compete for the same nutrients, potentially impacting nutritional homeostasis. Our knowledge of outcome of the interaction in terms of metal homeostasis is still limited. Here, we employed the X-ray fluorescence microscopy (XFM) beamline at the Australian Synchrotron to visualize and analyse the fate of nutrients in wheat leaves infected with Pyrenophora tritici-repentis, a necrotrophic fungal pathogen. We sought to (i) evaluate the utility of XFM for sub-micron mapping of essential mineral nutrients and (ii) examine the spatiotemporal impact of a pathogen on nutrient distribution in leaves. XFM maps of K, Ca, Fe, Cu, Mn, and Zn revealed substantial hyperaccumulation within, and depletion around, the infected region relative to uninfected control samples. Fungal mycelia were visualized as thread-like structures in the Cu and Zn maps. The hyperaccumulation of Mn in the lesion and localized depletion in asymptomatic tissue surrounding the lesion was unexpected. Similarly, Ca accumulated at the periphery of the symptomatic region and as microaccumulations aligning with fungal mycelia. Collectively, our results highlight that XFM imaging provides the capability for high-resolution mapping of elements to probe nutrient distribution in hydrated diseased leaves in situ. © The Author(s) 2021. Published by Oxford University Press on behalf of the Society for Experimental Biology.