“Wax On, Wax Off”: In Vivo Imaging of Plant Physiology and Disease with Fourier Transform Infrared Reflectance Microspectroscopy

Analysis of the epicuticular wax layer on the surface of plant leaves can provide a unique window into plant physiology and responses to environmental stimuli. Well-established analytical methodologies can quantify epicuticular wax composition, yet few methods are capable of imaging wax distribution in situ or in vivo. Here, the first report of Fourier transform infrared (FTIR) reflectance spectroscopic imaging as a non-destructive, in situ, method to investigate variation in epicuticular wax distribution at 25 µm spatial resolution is presented. The authors demonstrate in vivo imaging of alterations in epicuticular waxes during leaf development and in situ imaging during plant disease or exposure to environmental stressors. It is envisaged that this new analytical capability will enable in vivo studies of plants to provide insights into how the physiology of plants and crops respond to environmental stresses such as disease, soil contamination, drought, soil acidity, and climate change

The Pentatricopeptide Repeat Protein MEF100 Is Required for the Editing of Four Mitochondrial Editing Sites in <i>Arabidopsis</i>

In Arabidopsis thaliana there are more than 600 C-to-U RNA editing events in the mitochondria and at least 44 in the chloroplasts. Pentatricopeptide repeat (PPR) proteins provide the specificity for these reactions. They recognize RNA sequences in a partially predictable fashion via key amino acids at the fifth and last position in each PPR motif that bind to individual ribonucleotides. A combined approach of RNA-Seq, mutant complementation, electrophoresis of mitochondrial protein complexes and Western blotting allowed us to show that MEF100, a PPR protein identified in a genetic screen for mutants resistant to an inhibitor of γ -glutamylcysteine synthetase, is required for the editing of nad1-493, nad4-403, nad7-698 and ccmFN2-356 sites in Arabidopsis mitochondria. The absence of editing in mef100 leads to a decrease in mitochondrial Complex I activity, which probably explains the physiological phenotype. Some plants have lost the requirement for MEF100 at one or more of these sites through mutations in the mitochondrial genome. We show that loss of the requirement for MEF100 editing leads to divergence in the MEF100 binding site

Synchrotron X-ray fluorescence microscopy-enabled elemental mapping illuminates the “battle for nutrients” between plant and pathogen

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 on nutritional homeostasis. Our knowledge of outcome of the interaction in terms of metal homeostasis is still limited. Here, we employed X-ray fluorescence microscopy (XFM) beamline at the Australian Synchrotron to visualise 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 visualised as threadlike structures in the Cu and Zn maps. The hyperaccumulation of Mn in the lesion and localised depletion in asymptomatic tissue surrounding the lesion was unexpected. Similarly, Ca accumulated at the periphery of symptomatic region and as micro-accumulations aligning with fungal mycelia. Collectively, our results highlight that XFM imaging provides capability for high resolution mapping of elements to probe nutrient distribution in hydrated diseased leaves in situ

Oral and cutaneous manifestations of covid-19 in pediatric patients

ABSTRACT COVID-19 began in December 2019 in Wuhan City, China, and on March 11, 2020 it was classified by the World Health Organization as a pandemic. It is an asymptomatic infection that can progress to severe respiratory conditions. In adults, it is more prevalent, but is also observed in children, with the occurrence of extra respiratory symptoms, such as oral and cutaneous manifestations. This literature review aims to report the oral and cutaneous manifestations of COVID-19 in pediatric patients. The bibliographic search strategy was carried out in the PubMed, SciELO and Bireme databases on August 1, 2020, using MeSH Terms “COVID-19”; “Child”; “Oral Manifestations”; “Skin Manifestations”; “Ageusia”; “Dysgeusia” and corresponding Decs, and also manual search, without language restriction. The stages of search, screening, selection, evaluation of studies and data extraction were performed by four independent reviewers. Nine studies that met the eligibility criteria were identified. The most cited oral and cutaneous manifestations were, respectively, taste dysfunction in adolescents and erythematous eruption in extremities and trunk. Health professionals should be aware of these manifestations, however, this is a recent theme in the literature, and more careful studies with greater strength of evidence still need to be performed

Photosynthetic and metabolic acclimation to repeated drought events play key roles in drought tolerance in coffee

Over the last decades, most information on the mechanisms underlying tolerance to drought has been gained by considering this stress as a single event that happens just once in the life of a plant, in contrast to what occurs under natural conditions where recurrent drought episodes are the rule. Here we explored mechanisms of drought toler- ance in coffee (Coffea canephora) plants from a broader perspective, integrating key aspects of plant physiology and biochemistry. We show that plants exposed to multiple drought events displayed higher photosynthetic rates, which were largely accounted for by biochemical rather than diffusive or hydraulic factors, than those submitted to drought for the first time. Indeed, these plants displayed higher activities of RuBisCO and other enzymes associated with car- bon and antioxidant metabolism. Acclimation to multiple drought events involved the expression of trainable genes related to drought tolerance and was also associated with a deep metabolite reprogramming with concordant altera- tions in central metabolic processes such as respiration and photorespiration. Our results demonstrate that plants exposed to multiple drought cycles can develop a differential acclimation that potentiates their defence mechanisms, allowing them to be kept in an ‘alert state’ to successfully cope with further drought events