The plant ER-Golgi interface: a highly structured and dynamic membrane complex. J Exp Bot 58: 49-64
ABSTRACT As compared with other eukaryotic cells, plants have developed an endoplasmic reticulum (ER)-Golgi interface with very specific structural characteristics. ER to Golgi and Golgi to ER transport appear not to be dependent on the cytoskeleton, and ER export sites have been found closely associated with Golgi bodies to constitute entire mobile units. However, the molecular machinery involved in membrane trafficking seems to be relatively conserved among eukaryotes. Therefore, a challenge for plant scientists is to determine how these molecular machineries work in a different structural and dynamic organization. This review will focus on some aspects of membrane dynamics that involve coat proteins, SNAREs (soluble N-ethylmaleimide-sensitive factor attachment receptor proteins), lipids, and lipid-interacting proteins.
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ABSTRACT: Hexaploid bread wheat (Triticum aestivum L.) is one of the major crops grown and consumed all over the world. Elevated soil-salinity causes reduction in crop yield and quality; therefore several strategies were developed to improve salt-tolerant cultivars. MicroRNAs (miRNAs), small and noncoding RNAs, regulate gene expression at post-transcriptional level and play important roles in stress tolerance. Here, we used a broad-range miRNA-microarray analysis to investigate the root-miRNA profiles of two cultivars, Bezostaja (sensitive) and Seri-82 (tolerant). A total of 44 differentially–regulated miRNAs were identified in the 8x15K array containing 11,862 plant miRNAs available in the database. Sixteen novel salt-responsive miRNAs were determined in wheat for the first time. The expression of three miRNAs (hvu-miR5049a, ppt-miR1074, and osa-miR444b.2) was up-regulated more than 260-fold in cv. Bezostaja upon salt stress. The target-gene analyses showed that several salt–stress-responsive miRNAs regulate mainly transcription factors such as bHLH135-like, AP2/ERBP, MADS-box and transporters. Gene-ontology searches for 565 putative salt-stress-responsive miRNA target-genes revealed 623 processes in ten different main topics such as metabolic process and response to stimuli. The genome-wide root miRNome study indicates salt-stress-responsive wheat miRNAs and the possible mechanisms behind the tolerance.Annals of Applied Biology 03/2015; DOI:10.1111/aab.12219
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ABSTRACT: In the present study we employ FIB/SEM tomography for analyzing 3-D architecture of dictyosomes and formation of multivesicular bodies (MVB) in high pressure frozen and cryo-substituted interphase cells of the green algal model system Micrasterias denticulata. The ability of FIB/SEM of milling very thin ‘slices’ (5–10 nm), viewing the block face and of capturing cytoplasmic volumes of several hundred μm3 provides new insight into the close spatial connection of the ER–Golgi machinery in an algal cell particularly in z-direction, complementary to informations obtained by TEM serial sectioning or electron tomography. Our FIB/SEM series and 3-D reconstructions show that interphase dictyosomes of Micrasterias are not only closely associated to an ER system at their cis-side which is common in various plant cells, but are surrounded by a huge “trans-ER” sheath leading to an almost complete enwrapping of dictyosomes by the ER. This is particularly interesting as the presence of a trans-dictyosomal ER system is well known from mammalian secretory cells but not from cells of higher plants to which the alga Micrasterias is closely related. In contrast to findings in plant storage tissue indicating that MVBs originate from the trans-Golgi network or its derivatives our investigations show that MVBs in Micrasterias are in direct spatial contact with both, trans-Golgi cisternae and the trans-ER sheath which provides evidence that both endomembrane compartments are involved in their formation.Journal of Structural Biology 10/2013; 184(2). DOI:10.1016/j.jsb.2013.10.003
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ABSTRACT: Movement of secretory organelles is a fascinating yet largely mysterious feature of eukaryotic cells. Microtubule-based endomembrane and organelle motility utilizing the motor proteins dynein and kinesin is commonplace in animal cells. In contrast, it has been long accepted that intracellular motility in plant cells is predominantly driven by myosin motors dragging organelles and endomembrane-bounded cargo along actin filament bundles. Consistent with this, defects in the acto-myosin cytoskeleton compromise plant growth and development. Recent findings, however, challenge the actin-centric view of the motility of critical secretory organelles and distribution of associated protein machinery. In this review, we provide an overview of current knowledge on actin-mediated organelle movement within the secretory pathway of plant cells and report on recent and exciting findings that support a critical role of microtubules in plant cell development, in fine-tuning the positioning of Golgi stacks as well as their involvement in cellulose synthesis and auxin polar transport. These emerging aspects of the biology of microtubules highlight adaptations of an ancestral machinery that plants have specifically evolved to support the functioning of the acto-myosin cytoskeleton, and mark new trends in our global appreciation of the complexity of organelle movement within the plant secretory pathway. This article is protected by copyright. All rights reserved.The Plant Journal 05/2013; 75(2). DOI:10.1111/tpj.12227