The poplar rust fungus is part of one of the most devastating group of fungi (Pucciniales) and causes important economic losses to the poplar industry. Because is a heteroecious obligate biotroph, its spread depends on its ability to carry out its reproductive cycle through larch and then poplar parasitism. Genomic approaches have identified more than 1,000 candidate secreted effector proteins (CSEPs) from the predicted secretome of that are potentially implicated in the infection process.
View Article and Find Full Text PDFIn plant cells, plastids form elongated extensions called stromules, the regulation and purposes of which remain unclear. Here, we quantitatively explore how different stromule structures serve to enhance the ability of a plastid to interact with other organelles: increasing the effective space for interaction and biomolecular exchange between organelles. Interestingly, electron microscopy and confocal imaging showed that the cytoplasm in Arabidopsis thaliana and Nicotiana benthamiana epidermal cells is extremely thin (around 100 nm in regions without organelles), meaning that inter-organelle interactions effectively take place in 2D.
View Article and Find Full Text PDFIn Nicotiana benthamiana, the expression of the Xanthomonas effector XANTHOMONAS OUTER PROTEIN Q (XopQ) triggers RECOGNITION OF XOPQ1 (ROQ1)-dependent effector-triggered immunity (ETI) responses accompanied by the accumulation of plastids around the nucleus and the formation of stromules. Both plastid clustering and stromules were proposed to contribute to ETI-related hypersensitive cell death and thereby to plant immunity. Whether these reactions are directly connected to ETI signaling events has not been tested.
View Article and Find Full Text PDFManganese (Mn2+) is essential for a diversity of processes, including photosynthetic water splitting and the transfer of glycosyl moieties. Various Golgi-localized glycosyltransferases that mediate cell wall matrix polysaccharide biosynthesis are Mn2+ dependent, but the supply of these enzymes with Mn2+ is not well understood. Here, we show that the BIVALENT CATION TRANSPORTER 3 (BICAT3) localizes specifically to trans-cisternae of the Golgi.
View Article and Find Full Text PDFDespite its central role as the ark of genetic information and gene expression the plant nucleus is surprisingly understudied. We isolated nuclei from the dark grown cell culture left untreated and treated with flg22 and nlp20, two elicitors of pattern triggered immunity (PTI) in plants, respectively. An liquid chromatography mass spectrometry (LC-MS) based discovery proteomics approach was used to measure the nuclear proteome fractions.
View Article and Find Full Text PDFUpon immune activation, chloroplasts switch off photosynthesis, produce antimicrobial compounds and associate with the nucleus through tubular extensions called stromules. Although it is well established that chloroplasts alter their position in response to light, little is known about the dynamics of chloroplast movement in response to pathogen attack. Here, we report that during infection with the Irish potato famine pathogen Phytophthora infestans, chloroplasts accumulate at the pathogen interface, associating with the specialized membrane that engulfs the pathogen haustorium.
View Article and Find Full Text PDFPathogens modulate plant cell structure and function by secreting effectors into host tissues. Effectors typically function by associating with host molecules and modulating their activities. This study aimed to identify the host processes targeted by the RXLR class of host-translocated effectors of the potato blight pathogen Phytophthora infestans.
View Article and Find Full Text PDFHydathodes are organs found on aerial parts of a wide range of plant species that provide almost direct access for several pathogenic microbes to the plant vascular system. Hydathodes are better known as the site of guttation, which is the release of droplets of plant apoplastic fluid to the outer leaf surface. Because these organs are only described through sporadic allusions in the literature, this review aims to provide a comprehensive view of hydathode development, physiology, and immunity by compiling a historic and contemporary bibliography.
View Article and Find Full Text PDFCurr Opin Plant Biol
December 2018
Plastids undergo drastic shape changes under stress, including the formation of stroma-filled tubules, or `stromules'. Stromules are dynamic, and may extend, branch and retract within minutes. There are two prerequisites for stromule extension: excess plastid membrane and a force(s) that shapes the membrane into a tubule.
View Article and Find Full Text PDFXanthomonas campestris pv. vesicatoria type III-secreted effectors were screened for candidates influencing plant cell processes relevant to the formation and maintenance of stromules in Nicotiana benthamiana lower leaf epidermis. Transient expression of XopL, a unique type of E3 ubiquitin ligase, led to a nearly complete elimination of stromules and the relocation of plastids to the nucleus.
View Article and Find Full Text PDFPlastids send "retrograde" signals to the nucleus to deliver information regarding their physiological status. One open question concerning this signal transfer is how the signal bridges the cytoplasm. Based on individual reports of plastid derived tubular membrane extensions connecting to nuclei, these so-called stromules have been suggested to function as communication routes between plastids and nuclei in response to biotic stress.
View Article and Find Full Text PDFAnnotation of protein-coding genes is very important in bioinformatics and biology and has a decisive influence on many downstream analyses. Homology-based gene prediction programs allow for transferring knowledge about protein-coding genes from an annotated organism to an organism of interest.Here, we present a homology-based gene prediction program called GeMoMa.
View Article and Find Full Text PDFA strategy to detect and quantify the polar ethylene precursor 1-aminocyclopropan-1-carboxylic acid (ACC) along with the more apolar phytohormones abscisic acid (ABA), indole-3-acetic acid (IAA), jasmonic acid (JA), jasmonic acid-isoleucine conjugate (JA-Ile), 12-oxo-phytodienoic acid (OPDA), trans-zeatin, and trans-zeatin 9-riboside using a single extraction is presented. Solid phase resins commonly employed for extraction of phytohormones do not allow the recovery of ACC. We circumvent this problem by attaching an apolar group to ACC via derivatization with the amino group specific reagent 9-fluorenylmethoxycarbonyl chloride (Fmoc-Cl).
View Article and Find Full Text PDFStudies spread over nearly two and a half centuries have identified the primary plastid in autotrophic algae and plants as a pleomorphic, multifunctional organelle comprising of a double-membrane envelope enclosing an organization of internal membranes submerged in a watery stroma. All plastid units have been observed extending and retracting thin stroma-filled tubules named stromules sporadically. Observations on living plant cells often convey the impression that stromules connect two or more independent plastids with each other.
View Article and Find Full Text PDFBackground: Agrobacterium tumefaciens-based transient assays have become a common tool for answering questions related to protein localization and gene expression in a cellular context. The use of these assays assumes that the transiently transformed cells are observed under relatively authentic physiological conditions and maintain 'normal' sub-cellular behaviour. Although this premise is widely accepted, the question of whether cellular organization and organelle morphology is altered in Agrobacterium-infiltrated cells has not been examined in detail.
View Article and Find Full Text PDFCytoplasmic dynein is a motor protein that exerts force on microtubules. To generate force for the movement of large organelles, dynein needs to be anchored, with the anchoring sites being typically located at the cell cortex. However, the mechanism by which dyneins target sites where they can generate large collective forces is unknown.
View Article and Find Full Text PDFPlant Signal Behav
September 2012
The recognition of stromules as sporadically extended stroma filled tubules from all kinds of plastids constitutes one of the major insights that resulted from the direct application of green fluorescent protein aided imaging of living plant cells. Observations of dynamic green fluorescent stromules strongly suggested that plastids frequently interact with each other while photo-bleaching of interconnected plastids indicated that proteins can move within the stroma filled tubules. These observations readily fit into the prevailing concept of the endosymbiogenic origins of plastids and provided stromules the status of conduits for inter-plastid communication and macromolecule transfer.
View Article and Find Full Text PDFStroma-filled tubules named stromules are sporadic extensions of plastids. Earlier, photobleaching was used to demonstrate fluorescent protein diffusion between already interconnected plastids and formed the basis for suggesting that all plastids are able to form networks for exchanging macromolecules. However, a critical appraisal of literature shows that this conjecture is not supported by unequivocal experimental evidence.
View Article and Find Full Text PDFNumerous subcellular-targeted probes have been created using a monomeric green-to-red photoconvertible Eos fluorescent protein for understanding the growth and development of plants. These probes can be used to create color-based differentiation between similar cells, differentially label organelle subpopulations, and track subcellular structures and their interactions. Both green and red fluorescent forms of mEosFP are stable and compatible with single colored FPs.
View Article and Find Full Text PDFMany higher plants are polysomatic whereby different cells possess variable amounts of nuclear DNA. The conditional triggering of endocycles results in higher nuclear DNA content (C value) that in some cases has been correlated to increased cell size. While numerous multicolored fluorescent protein (FP) probes have revealed the general behavior of the nucleus and intranuclear components, direct visualization and estimation of changes in nuclear-DNA content in live cells during their development has not been possible.
View Article and Find Full Text PDFBackground: Stromules are dynamic tubular structures emerging from the surface of plastids that are filled with stroma. Despite considerable progress in understanding the importance of certain cytoskeleton elements and motor proteins for stromule maintenance, their function within the plant cell is still unknown. It has been suggested that stromules facilitate the exchange of metabolites and/or signals between plastids and other cell compartments by increasing the cytosolically exposed plastid surface area but experimental evidence for the involvement of stromules in metabolic processes is not available.
View Article and Find Full Text PDFStromules are extended by plastids but the underlying basis for their extension and retraction had not been understood until recently. Our live-imaging aided observations on coincident plastid stromule branching and ER tubule dynamics open out new areas of investigation relating to these rapid subcellular interactions. The addendum provides a testable hypothesis on the formation of stromules, which argues against the need for new membrane incorporation and suggests that stromal extensions might result from a remodeling of the plastid envelope membrane in an ER aided manner.
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