Pectin Methylesterases: Cell Wall Remodeling Proteins Are Required for Plant Response to Heat Stress

Heat stress (HS) is expected to be of increasing worldwide concern in the near future, especially with regard to crop yield and quality as a consequence of rising or varying temperatures as a result of global climate change. HS response (HSR) is a highly conserved mechanism among different organisms but shows remarkable complexity and unique features in plants. The transcriptional regulation of HSR is controlled by HS transcription factors (HSFs) which allow the activation of HS-responsive genes, among which HS proteins (HSPs) are best characterized. Cell wall remodeling constitutes an important component of plant responses to HS to maintain overall function and growth; however, little is known about the connection between cell wall remodeling and HSR. Pectin controls cell wall porosity and has been shown to exhibit structural variation during plant growth and in response to HS. Pectin methylesterases (PMEs) are present in multigene families and encode isoforms with different action patterns by removal of methyl esters to influencing the properties of cell wall. We aimed to elucidate how plant cell walls respond to certain environmental cues through cell wall-modifying proteins in connection with modifications in cell wall machinery. An overview of recent findings shed light on PMEs contribute to a change in cell-wall composition/structure. The fine-scale modulation of apoplastic calcium ions (Ca2+) content could be mediated by PMEs in response to abiotic stress for both the assembly and disassembly of the pectic network. In particular, this modulation is prevalent in guard cell walls for regulating cell wall plasticity as well as stromal aperture size, which comprise critical determinants of plant adaptation to HS. These insights provide a foundation for further research to reveal details of the cell wall machinery and stress-responsive factors to provide targets and strategies to facilitate plant adaptation

Catechin production in cultured cells of Taxus cuspidata and Taxus baccata

Abstract The main polyphenols in callus and cell suspension cultures of Taxus cuspidata and T. baccata were (?)-catechin and (-)-epicatechin, while lignans, such as (?)-taxiresinol, (?)-isotaxiresinol, (?)-isolariciresinol and (-)-secoisolariciresinol, were present in trace amounts. T. cuspidata cells contained 1.7% (?)-catechin and 2.4% (-)-epicatechin on dry wt basis but when stimulated with methyl jasmonate produced 3.4% catechin and 5.2% epicatechin. These are the highest levels of these metabolites obtained in plant cell cultures

A Brief Overview of Potential Treatments for Viral Diseases Using Natural Plant Compounds: The Case of SARS-Cov

Review paper, jointly written by experts from Universiti Putra Malaysia, Taras Shevchenko National University of Kyiv (Ukraine), Kermanshah University of Medical Sciences (Iran), Federal University of Maranhão (Brazil), Central University of Punjab (India), Federal Scientific Center of the East Asia Terrestrial Biodiversity (Russia), De Montfort University (UK), University of Orléans (France) open access articleThe COVID-19 pandemic, as well as the more general global increase in viral diseases, has led researchers to look to the plant kingdom as a potential source for antiviral compounds. Since ancient times, herbal medicines have been extensively applied in the treatment and prevention of various infectious diseases in different traditional systems. The purpose of this review is to highlight the potential antiviral activity of plant compounds as effective and reliable agents against viral infections, especially by viruses from the coronavirus group. Various antiviral mechanisms shown by crude plant extracts and plant-derived bioactive compounds are discussed. The understanding of the action mechanisms of complex plant extract and isolated plant-derived compounds will help pave the way towards the combat of this life-threatening disease. Further, molecular docking studies, in silico analyses of extracted compounds, and future prospects are included. The in vitro production of antiviral chemical compounds from plants using molecular pharming is also considered. Notably, hairy root cultures represent a promising and sustainable way to obtain a range of biologically active compounds that may be applied in the development of novel antiviral agents

Linking Brassinosteroid and ABA Signaling in the Context of Stress Acclimation

The important regulatory role of brassinosteroids (BRs) in the mechanisms of tolerance to multiple stresses is well known. Growing data indicate that the phenomenon of BR-mediated drought stress tolerance can be explained by the generation of stress memory (the process known as ‘priming’ or ‘acclimation’). In this review, we summarize the data on BR and abscisic acid (ABA) signaling to show the interconnection between the pathways in the stress memory acquisition. Starting from brassinosteroid receptors brassinosteroid insensitive 1 (BRI1) and receptor-like protein kinase BRI1-like 3 (BRL3) and propagating through BR-signaling kinases 1 and 3 (BSK1/3) → BRI1 suppressor 1 (BSU1) ―‖ brassinosteroid insensitive 2 (BIN2) pathway, BR and ABA signaling are linked through BIN2 kinase. Bioinformatics data suggest possible modules by which BRs can affect the memory to drought or cold stresses. These are the BIN2 → SNF1-related protein kinases (SnRK2s) → abscisic acid responsive elements-binding factor 2 (ABF2) module; BRI1-EMS-supressor 1 (BES1) or brassinazole-resistant 1 protein (BZR1)–TOPLESS (TPL)–histone deacetylase 19 (HDA19) repressor complexes, and the BZR1/BES1 → flowering locus C (FLC)/flowering time control protein FCA (FCA) pathway. Acclimation processes can be also regulated by BR signaling associated with stress reactions caused by an accumulation of misfolded proteins in the endoplasmic reticulum

Proteomic Analysis of Proteins Related to Defense Responses in <i>Arabidopsis</i> Plants Transformed with the <i>rolB</i> Oncogene

During Agrobacterium rhizogenes–plant interaction, the rolB gene is transferred into the plant genome and is stably inherited in the plant’s offspring. Among the numerous effects of rolB on plant metabolism, including the activation of secondary metabolism, its effect on plant defense systems has not been sufficiently studied. In this work, we performed a proteomic analysis of rolB-expressing Arabidopsis thaliana plants with particular focus on defense proteins. We found a total of 77 overexpressed proteins and 64 underexpressed proteins in rolB-transformed plants using two-dimensional gel electrophoresis and MALDI mass spectrometry. In the rolB-transformed plants, we found a reduced amount of scaffold proteins RACK1A, RACK1B, and RACK1C, which are known as receptors for activated C-kinase 1. The proteomic analysis showed that rolB could suppress the plant immune system by suppressing the RNA-binding proteins GRP7, CP29B, and CP31B, which action are similar to the action of type-III bacterial effectors. At the same time, rolB plants induce the massive biosynthesis of protective proteins VSP1 and VSP2, as well as pathogenesis-related protein PR-4, which are markers of the activated jasmonate pathway. The increased contents of glutathione-S-transferases F6, F2, F10, U19, and DHAR1 and the osmotin-like defense protein OSM34 were found. The defense-associated protein PCaP1, which is required for oligogalacturonide-induced priming and immunity, was upregulated. Moreover, rolB-transformed plants showed the activation of all components of the PYK10 defense complex that is involved in the metabolism of glucosinolates. We hypothesized that various defense systems activated by rolB protect the host plant from competing phytopathogens and created an effective ecological niche for A. rhizogenes. A RolB → RACK1A signaling module was proposed that might exert most of the rolB-mediated effects on plant physiology. Our proteomics data are available via ProteomeXchange with identifier PXD037959

Tempo-Spatial Pattern of Stepharine Accumulation in <i>Stephania Glabra</i> Morphogenic Tissues

Alkaloids attract great attention due to their valuable therapeutic properties. Stepharine, an aporphine alkaloid of Stephania glabra plants, exhibits anti-aging, anti-hypertensive, and anti-viral effects. The distribution of aporphine alkaloids in cell cultures, as well as whole plants is unknown, which hampers the development of bioengineering strategies toward enhancing their production. The spatial distribution of stepharine in cell culture models, plantlets, and mature micropropagated plants was investigated at the cellular and organ levels. Stepharine biosynthesis was found to be highly spatially and temporally regulated during plant development. We proposed that self-intoxication is the most likely reason for the failure of the induction of alkaloid biosynthesis in cell cultures. During somatic embryo development, the toxic load of alkaloids inside the cells increased. Only specialized cell sites such as vascular tissues with companion cells (VT cells), laticifers, and parenchymal cells with inclusions (PI cells) can tolerate the accumulation of alkaloids, and thus circumvent this restriction. S. glabra plants have adapted to toxic pressure by forming an additional transport secretory (laticifer) system and depository PI cells. Postembryonic growth restricts specialized cell site formation during organ development. Future bioengineering strategies should include cultures enriched in the specific cells identified in this study

Critical analysis of protein signaling networks involved in the regulation of plant secondary metabolism: focus on anthocyanins

<p>Anthocyanin biosynthesis in <i>Arabidopsis</i> is a convenient and relatively simple model for investigating the basic principles of secondary metabolism regulation. In recent years, many publications have described links between anthocyanin biosynthesis and general defense reactions in plants as well as photomorphogenesis and hormonal signaling. These relationships are complex, and they cannot be understood intuitively. Upon observing the lacuna in the <i>Arabidopsis</i> interactome (an interaction map of the factors involved in the regulation of <i>Arabidopsis</i> secondary metabolism is not available), we attempted to connect various cellular processes that affect anthocyanin biosynthesis. In this review, we revealed the main signaling protein modules that regulate anthocyanin biosynthesis. To our knowledge, this is the first reconstruction of a network of proteins involved in plant secondary metabolism.</p