The deposition of the (1,3)-b-glucan cell wall polymer callose at sites of attempted penetration is a common plant defense response to intruding pathogens and part of the plant's innate immunity. Infection of the Fusarium graminearum disruption mutant Dfgl1, which lacks the effector lipase FGL1, is restricted to inoculated wheat (Triticum aestivum) spikelets, whereas the wild-type strain colonized the whole wheat spike. Our studies here were aimed at analyzing the role of FGL1 in establishing full F. graminearum virulence. Confocal laser-scanning microscopy revealed that the Dfgl1 mutant strongly induced the deposition of spot-like callose patches in vascular bundles of directly inoculated spikelets, while these callose deposits were not observed in infections by the wild type. Elevated concentrations of the polyunsaturated free fatty acids (FFAs) linoleic and a-linolenic acid, which we detected in F. graminearum wild type-infected wheat spike tissue compared with Dfgl1-infected tissue, provided clear evidence for a suggested function of FGL1 in suppressing callose biosynthesis. These FFAs not only inhibited plant callose biosynthesis in vitro and in planta but also partially restored virulence to the Dfgl1 mutant when applied during infection of wheat spikelets. Additional FFA analysis confirmed that the purified effector lipase FGL1 was sufficient to release linoleic and a-linolenic acids from wheat spike tissue. We concluded that these two FFAs have a major function in the suppression of the innate immunity-related callose biosynthesis and, hence, the progress of F. graminearum wheat infection.
ReuseUnless indicated otherwise, fulltext items are protected by copyright with all rights reserved. The copyright exception in section 29 of the Copyright, Designs and Patents Act 1988 allows the making of a single copy solely for the purpose of non-commercial research or private study within the limits of fair dealing. The publisher or other rights-holder may allow further reproduction and re-use of this version -refer to the White Rose Research Online record for this item. Where records identify the publisher as the copyright holder, users can verify any specific terms of use on the publisher's website. TakedownIf you consider content in White Rose Research Online to be in breach of UK law, please notify us by emailing eprints@whiterose.ac.uk including the URL of the record and the reason for the withdrawal request. P r o o fNumeric scoring system for rating the disease severity of F. graminearum-infected B. distachyon spikelets.156x77mm (300 x 300 DPI) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60Based on its phylogeny and morphology, the small annual grass Brachypodium 3 distachyon has emerged as a model system for the investigation of Triticeae (Catalán 4 et al., 1995, Vogel & Bragg, 2009, Vogel et al., 2006. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 and wilting (Cutler, 1988 to break type II resistance and to fully colonize the spike (Proctor et al., 1995 wheat spikelets (Voigt et al., 2005, Blümke et al., 2014. In the initial phase of 15In B. distachyon, we observed a slight hyphal growth of the gpmk1GFP mutant only 16 at the point of direct inoculation within the floret (Fig. 2D) (Fig. 3A), were comparable to the amounts described in previous reports of 21B. distachyon and other grasses (Christensen et al., 2010, Gomez et al., 2008. (Fig. 3A). Apart from glucose, we did not observed 2 alterations for the other neutral monosaccharides (Fig. 3A). At 14 dpi, we observed a 3 shift in the glucose/xylose ratio in the waterinoculated control tissue where the 4 glucose content increased to almost 30 mol%, which correlated with a decrease in the 5 xylose content to 58 mol%. The relative amounts of arabinose and galactose remained 6 unchanged compared to 7 dpi, which also applied to the F. graminearuminfected 7 samples for these monosaccharides (Fig. 3B). Whereas we did not detect differences 8 in the cell wall composition between control and tri5GFPinfected samples, 9 infection of spikelets with the F. graminearum...
Localized cell wall thickenings, so called papillae, are a common plant defense response to fungal attack at sites of penetration of the plant cell. The major constituent of papillae is callose, a (1,3)-β-glucan polymer, which contributes to slowing or blocking the invading fungal hyphae. In the model plant Arabidopsis thaliana, we could recently show that the overexpression of PMR4 (POWDERY MILDEW RESITANT 4), which encodes a stress induced callose synthase, results in complete powdery mildew resistance. To evaluate if these findings are also transferable to monocot crops, we transiently expressed PMR4 under control of the 35S promoter in leaves of barley (Hordeum vulgare) seedlings, which were subsequently inoculated with the virulent powdery mildew Blumeria graminis f. sp. hordei. Fusion of the green fluorescent protein (GFP) to PMR4 allowed the identification of successfully transformed barley cells, which showed an increased penetration resistance to B. graminis compared to control cells that express only GFP. PMR4-GFP localized in a similar pattern at the site of attempted fungal penetration as observed in A. thaliana, which suggests that similar transport mechanisms of the callose synthase might exist in dicot and monocot plants.
Converting biomass to biofuels is a key strategy in substituting fossil fuels to mitigate climate change. Conventional strategies to convert lignocellulosic biomass to ethanol address the fermentation of cellulose-derived glucose. Here we used super-resolution fluorescence microscopy to uncover the nanoscale structure of cell walls in the energy crops maize and Miscanthus where the typical polymer cellulose forms an unconventional layered architecture with the atypical (1, 3)-β-glucan polymer callose. This raised the question about an unused potential of (1, 3)-β-glucan in the fermentation of lignocellulosic biomass. Engineering biomass conversion for optimized (1, 3)-β-glucan utilization, we increased the ethanol yield from both energy crops. The generation of transgenic Miscanthus lines with an elevated (1, 3)-β-glucan content further increased ethanol yield providing a new strategy in energy crop breeding. Applying the (1, 3)-β-glucan-optimized conversion method on marine biomass from brown macroalgae with a naturally high (1, 3)-β-glucan content, we not only substantially increased ethanol yield but also demonstrated an effective co-fermentation of plant and marine biomass. This opens new perspectives in combining different kinds of feedstock for sustainable and efficient biofuel production, especially in coastal regions.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.