Expression of stress-response proteins upon whitefly-mediated inoculation of Tomato yellow leaf curl virus in susceptible and resistant tomato plants

To better understand the nature of resistance of tomato to the whitefly (Bemisia tabaci, B biotype)-transmitted Tomato yellow leaf curl virus (TYLCV), whiteflies and TYLCV were considered as particular cases of biotic stresses and virus resistance as a particular case of successful response to these stresses. Two inbred tomato lines issued from the same breeding program that used Solanum habrochaites as a TYLCV resistance source, one susceptible and the other resistant, were used to compare the expression of key proteins involved at different stages of the plant response with stresses: mitogen-activated protein kinases (MAPKs), cellular heat shock proteins (HSPs, proteases), and pathogenesis-related (PR) proteins. The two biotic stresses-non-viruliferous whitefly feeding and virus infection with viruliferous insects--led to a slow decline in abundance of MAPKs, HSPs, and chloroplast protease FtsH (but not chloroplast protease ClpC), and induced the activities of the PR proteins, beta-1,3-glucanase, and peroxidase. This decline was less pronounced in virus-resistant than in virus-susceptible lines. Contrary to whitefly infestation and virus infection, inoculation with the fungus Sclerotinia sclerotiorum induced a rapid accumulation of the stress proteins studied, followed by a decline; the virus-susceptible and -resistant tomato lines behaved similarly in response to the fungus.     

Essential metals,vitamins and antioxidant enzyme activities in COVID-19 patients and their potential associations with the disease severity

BioMetals - The role of micronutrient deficiency in the pathogenesis of COVID-19 has been reviewed in the literature; however, the data are limited and conflicting. This study investigated the...     

Interactions of mouse glycophorin A with the dRTA-related mutant G719D of the mouse Cl-/HCO3- exchanger Ae1

The AE1 mutation G701D, associated with recessive distal renal tubular acidosis (dRTA), produces only minimal erythroid phenotype, reflecting erythroid-specific expression of stimulatory AE1 subunit glycophorin A (GPA). GPA transgene expression could theoretically treat recessive dRTA in patients and in mice expressing cognate Ae1 mutation G719D. However, human (h) GPA and mouse (m) Gpa amino acid sequences are widely divergent, and mGpa function in vitro has not been investigated. We therefore studied in Xenopus oocytes the effects of coexpressed mGpa and hGPA on anion transport by erythroid (e) and kidney (k) isoforms of wild-type mAe1 (meAe1, mkAe1) and of mAe1 mutant G719D. Coexpression of hGPA or mGpa enhanced the function of meAe1 and mkAe1 and rescued the nonfunctional meAe1 and mkAe1 G719D mutants through increased surface expression. Progressive N-terminal truncation studies revealed a role for meAe1 amino acids 22-28 in GPA-responsiveness of meAe1 G719D. MouseN-cyto/humanTMD and humanN-cyto/mouseTMD kAE1 chimeras were active and GPA-responsive. In contrast, whereas chimera mkAe1N-cyto/hkAE1 G701DTMD was GPA-responsive, chimera hkAE1N-cyto/mkAe1 G719DTMD was GPA-insensitive. Moreover, whereas the isolated transmembrane domain (TMD) of hAE1 G701D was GPA-responsive, that of mAe1 G719D was GPA-insensitive. Thus, mGpa increases surface expression and activity of meAe1 and mkAe1. However, the G719D mutation renders certain mAe1 mutant constructs GPA-unresponsive and highlights a role for erythroid-specific meAe1 amino acids 22-28 in GPA-responsiveness.     

Lead phytotoxicity on wheat (Triticum aestivum L.) seed germination and seedlings growth

Lead (Pb) is an environmental pollutant extremely toxic to plants and other living organisms including humans. To assess Pb phytotoxicity, experiments focusing on germination of wheat seeds were germinated in a solution containing Pb (NO(3))(2) (0.05; 0.1; 0.5; 1g/L) during 6 days. Lead accumulation in seedlings was positively correlated with the external concentrations, and negatively correlated with morphological parameters of plant growth. Lead increased lipid peroxidation, enhanced soluble protein concentrations and induced a significant accumulation of proline in roots. Esterase activity was enhanced in the presence of lead, whereas α-amylase activity was significantly inhibited. Antioxidant enzymes activities, such as, ascorbate peroxidase, peroxidase, superoxide dismutase, catalase and glutathione S-transferase were generally significantly increased in the presence of lead in a dose-dependent manner. The present results thus provide a model system to screen for natural compounds able to counteract the deleterious effects of lead.     

Integrated dataset of screening hits against multiple neglected disease pathogens

New chemical entities are desperately needed that overcome the limitations of existing drugs for neglected diseases. Screening a diverse library of 10,000 drug-like compounds against 7 neglected disease pathogens resulted in an integrated dataset of 744 hits. We discuss the prioritization of these hits for each pathogen and the strong correlation observed between compounds active against more than two pathogens and mammalian cell toxicity. Our work suggests that the efficiency of early drug discovery for neglected diseases can be enhanced through a collaborative, multi-pathogen approach.     

Assessment of genetic diversity of Mediterranean bread wheat using Randomly Amplified Polymorphic DNA (RAPD) markers

The genetic diversity of 14 bread wheat (Triticum aestivum L.) varieties originating from Mediterranean region (Egypt and Greece) was assessed by means of Randomly Amplified Polymorphic DNA (RAPD) markers. Seventeen RAPD markers were used to analyze and compare genetic diversity among the selected wheat varieties. Average of similarity coefficients based on RAPD markers for all of the studied varieties was 0.718. Average and range of genetic similarity coefficients among varieties obtained from both Egypt and Greece independently were 0.765 (from 0.66 to 0.886) and 0.723 (from 0.604 to 0.896), respectively. The cophenetic correlation coefficients of the three RAPD dendrograms (generated for all of the 14 varieties, the seven Egyptian varieties separately and the seven Greek varieties separately) were r = 0.774, 0.80, and 0.74, respectively. Both cluster analysis and Principal Coordinate Analysis (PCOORDA) were able to differentiate between Egyptian and Greek wheat varieties, but PCOORDA was more efficient in its separation. The percentage of variance accounted for the first two principal coordinates was 49.45% of total genetic variance for RAPD. Notable geographical divergence was found between Egyptian and Greek wheat varieties.     

Toxin-based in-vitro selection and its potential application to date palm for resistance to the bayoud Fusarium wilt

Date palm (Phoenix dactylifera L.) is qualified as a 'tree' of great ecological and socio-economical importance in desert oases. Unfortunately, it is being decimated, especially in Morocco and Algeria, by a fusariosis wilt called bayoud and caused by Fusarium oxysporum f. sp. albedinis (Fao). Controlling this disease requires the implementation of an integrated management program. Breeding for resistance is one of the most promising component strategies of this program. Few naturally resistant cultivars with a mediocre fruit quality (dates) are known. Conventional and non-conventional methods are under development and have to use the simplest and easiest methods to screen for resistant individuals. The use of pathogen toxins as selective agents at the tissue culture step might be a source of variability that can lead to the selection of individuals with suitable levels of resistance to the toxin and/or to the pathogen among the genetic material available. Foa produces toxins such as fusaric, succinic, 3-phenyl lactic acids and their derivatives, marasmins and peptidic toxins. These toxins can be used bulked or separately as selective agents. The aim of this contribution was to give a brief overview on toxins and their use as a mean to select resistant lines and to initiate a discussion about the potential use of this approach for the date palm-Foa pathosystem. This review does not pretend to be comprehensive or exhaustive and was prepared mainly to highlight the potential use of Foa toxins for selecting date palm individuals with a suitable resistance level to bayoud using toxin-based selective media.     

Cyclic adenosine monophosphate regulates calcium channels in the plasma membrane of Arabidopsis leaf guard and mesophyll cells

The effect of cAMP on Ca(2+)-permeable channels from Arabidopsis thaliana leaf guard cell and mesophyll cell protoplasts was studied using the patch clamp technique. In the whole cell configuration, dibutyryl cAMP was found to increase a hyperpolarization-activated Ba(2+) conductance (I(Ba)). The increase of I(Ba) was blocked by the addition of GdCl(3). In excised outside-out patches, the addition of dibutyryl cAMP consistently activated a channel with particularly fast gating kinetics. Current/voltage analyses indicated a single channel conductance of approximately 13 picosiemens. In patches where we measured some channel activity prior to cAMP application, the data suggest that cAMP enhances channel activity without affecting the single channel conductance. The cAMP activation of these channels was reversible upon washout. The results obtained with excised patches indicate that the cAMP-activated I(Ba) seen in the whole cell configuration could be explained by a direct effect of cAMP on the Ca(2+) channel itself or a close entity to the channel. This work represents the first demonstration using patch clamp analysis of the presence in plant cell membranes of an ion channel directly activated by cAMP.