Stomatal development in the grasses McKown, Katelyn H.; Bergmann, Dominique C.
The New phytologist,
September 2020, Letnik:
227, Številka:
6
Journal Article
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When plants emerged from their aquatic origins to colonise land, they needed to avoid desiccation while still enabling gas and water exchange with the environment. The solution was the development of ...a waxy cuticle interrupted by epidermal pores, known as stomata. Despite the importance of stomata in plant physiology and their contribution to global water and carbon cycles, our knowledge of the genetic basis of stomatal development is limited mostly to the model dicot, Arabidopsis thaliana. This limitation is particularly troublesome when evaluating grasses, whose members represent our most agriculturally significant crops. Grass stomatal development follows a trajectory strikingly different from Arabidopsis and their uniquely shaped four-celled stomatal complexes are especially responsive to environmental inputs. Thus, understanding the development and regulation of these efficient complexes is of particular interest for the purposes of crop engineering. This review focuses on genetic regulation of grass stomatal development and prospects for the future, highlighting discoveries enabled by parallel comparative investigations in cereal crops and related genetic model species such as Brachypodium distachyon.
The plant stomatal lineage manifests features common to many developmental contexts: precursor cells are chosen from an initially equivalent field of cells, undergo asymmetric and self-renewing ...divisions, communicate among themselves and respond to information from a distance. As we review here, the experimental accessibility of these epidermal lineages, particularly in Arabidopsis, has made stomata a conceptual and technical framework for the study of cell fate, stem cells, and cell polarity in plants.
Stomata are structures on the surfaces of most land plants that are required for gas exchange between plants and their environment. In
, stomata comprise two kidney bean-shaped epidermal guard cells ...that flank a central pore overlying a cavity in the mesophyll. These guard cells can adjust their shape to occlude or facilitate access to this pore, and in so doing regulate the release of water vapor and oxygen from the plant, in exchange for the intake of carbon dioxide from the atmosphere. Stomatal guard cells are the end product of a specialized lineage whose cell divisions and fate transitions ensure both the production and pattern of cells in aerial epidermal tissues. The stomatal lineage is dynamic and flexible, altering stomatal production in response to environmental change. As such, the stomatal lineage is an excellent system to study how flexible developmental transitions are regulated in plants. In this Cell Science at a Glance article and accompanying poster, we will summarize current knowledge of the divisions and fate decisions during stomatal development, discussing the role of transcriptional regulators, cell-cell signaling and polarity proteins. We will highlight recent work that links the core regulators to systemic or environmental information and provide an evolutionary perspective on stomata lineage regulators in plants.
Coronaviruses are of veterinary and medical importance and include highly pathogenic zoonotic viruses, such as SARS-CoV and MERS-CoV. They are known to efficiently evade early innate immune ...responses, manifesting in almost negligible expression of type-I interferons (IFN-I). This evasion strategy suggests an evolutionary conserved viral function that has evolved to prevent RNA-based sensing of infection in vertebrate hosts. Here we show that the coronavirus endonuclease (EndoU) activity is key to prevent early induction of double-stranded RNA (dsRNA) host cell responses. Replication of EndoU-deficient coronaviruses is greatly attenuated in vivo and severely restricted in primary cells even during the early phase of the infection. In macrophages we found immediate induction of IFN-I expression and RNase L-mediated breakdown of ribosomal RNA. Accordingly, EndoU-deficient viruses can retain replication only in cells that are deficient in IFN-I expression or sensing, and in cells lacking both RNase L and PKR. Collectively our results demonstrate that the coronavirus EndoU efficiently prevents simultaneous activation of host cell dsRNA sensors, such as Mda5, OAS and PKR. The localization of the EndoU activity at the site of viral RNA synthesis-within the replicase complex-suggests that coronaviruses have evolved a viral RNA decay pathway to evade early innate and intrinsic antiviral host cell responses.
Multicellular development depends on generating and precisely positioning distinct cell types within tissues. During leaf development, pores in the epidermis called stomata are spaced at least one ...cell apart for optimal gas exchange. This pattern is primarily driven by iterative asymmetric cell divisions (ACDs) in stomatal progenitors, which generate most of the cells in the tissue. A plasma membrane-associated polarity crescent defined by BREAKING OF ASYMMETRY IN THE STOMATAL LINEAGE (BASL) and BREVIS RADIX family (BRXf) proteins is required for asymmetric divisions and proper stomatal pattern, but the cellular mechanisms that orient ACDs remain unclear. Here, utilizing long-term, quantitative time-lapse microscopy, we identified two oppositely oriented nuclear migrations that precede and succeed ACD during epidermal patterning. The pre- and post-division migrations are dependent on microtubules and actin, respectively, and the polarity crescent is the unifying landmark that is both necessary and sufficient to orient both nuclear migrations. We identified a specific and essential role for MYOXI-I in controlling post-ACD nuclear migration. Loss of MYOXI-I decreases stomatal density, owing to an inability to accurately orient a specific subset of ACDs. Taken together, our analyses revealed successive and polarity-driven nuclear migrations that regulate ACD orientation in the Arabidopsis stomatal lineage.
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•Nuclear migrations flank asymmetric divisions in the Arabidopsis stomatal lineage•A BASL/BRXf polarity crescent orients both nuclear migrations•MYOXI-I is required for nuclear migration after asymmetric division•Loss of directed nuclear migrations correlates with division orientation defects
How are asymmetric divisions oriented in developing plant tissues? Muroyama et al. find that oppositely oriented nuclear migrations flank asymmetric divisions in the Arabidopsis stomatal lineage. Despite having distinct cytoskeletal requirements, both migrations use BASL as a spatial landmark and are collectively required for division orientation.
Background
The use of allergen immunotherapy (AIT) for allergic rhinitis and its clinical efficacy in clinical trials depends on the effective determination of pollen allergen exposure time periods. ...We evaluate pollen data from Germany to examine the new definitions on pollen season and peak pollen period start and end as proposed by the European Academy of Allergy and Clinical Immunology (EAACI) in a recently published Position Paper. The aim was to demonstrate the ability of these definitions to mirror symptom loads for grass and birch pollen‐induced allergic rhinitis based on real‐life data.
Methods
Data coming from four pollen monitoring stations in the Berlin and Brandenburg area in Germany and for 3 years (2014‐2016) were used to investigate the correlation of season definitions, birch and grass pollen counts and total nasal symptom and mediation scores as reported by patients in “Patients Hay fever Diaries” (PHDs). After the identification of pollen periods on the basis of the EACCI criteria, a statistical analysis was employed, followed by a detailed graphical investigation.
Results
The analysis revealed that the definitions of pollen season as well as peak pollen period start and end as proposed by the EAACI are correlated to symptom loads for grass and birch pollen‐induced allergic rhinitis reported by patients in PHDs.
Conclusion
Based on our analysis, the validity of the EAACI definitions on pollen season is confirmed. Their use is recommended in future clinical trials on AIT as well as in daily routine for optimal patient care.
The new EAACI definition of pollen season allows to pinpoint pollen season and peak pollen period start and end. Pollen season characteristics are correlated to symptom loads for grass and birch pollen‐induced allergic rhinitis symptoms reported by patients in Pollen Hay fever Diaries in Germany. The use of the new EAACI definition of pollen season is recommended in future clinical trials on allergen immunotherapy as well as in daily routine for optimal patient care.
The central nervous system (CNS) is vulnerable to several viral infections including herpes viruses, arboviruses and HIV to name a few. While a rapid and effective immune response is essential to ...limit viral spread and mortality, this anti-viral response needs to be tightly regulated in order to limit immune mediated tissue damage. This balance between effective virus control with limited pathology is especially important due to the highly specialized functions and limited regenerative capacity of neurons, which can be targets of direct virus cytolysis or bystander damage. CNS infection with the neurotropic strain of mouse hepatitis virus (MHV) induces an acute encephalomyelitis associated with focal areas of demyelination, which is sustained during viral persistence. Both innate and adaptive immune cells work in coordination to control virus replication. While type I interferons are essential to limit virus spread associated with early mortality, perforin, and interferon-γ promote further virus clearance in astrocytes/microglia and oligodendrocytes, respectively. Effective control of virus replication is nonetheless associated with tissue damage, characterized by demyelinating lesions. Interestingly, the anti-inflammatory cytokine IL-10 limits expansion of tissue lesions during chronic infection without affecting viral persistence. Thus, effective coordination of pro- and anti-inflammatory cytokines is essential during MHV induced encephalomyelitis in order to protect the host against viral infection at a limited cost.
Pollen and spore monitoring in the world Buters, J. T. M.; Antunes, C.; Galveias, A. ...
Clinical and translational allergy,
04/2018, Letnik:
8, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Background
Ambient air quality monitoring is a governmental duty that is widely carried out in order to detect non‐biological (“chemical”) components in ambient air, such as particles of < 10 µm ...(PM10, PM2.5 ), ozone, sulphur dioxide, and nitrogen oxides. These monitoring networks are publicly funded and air quality data are open to the public. The situation for biological particles that have detrimental effects on health, as is the case of pollen and fungal spores, is however very different. Most pollen and spore monitoring networks are not publicly funded and data are not freely available. The information regarding which biological particle is being monitored, where and by whom, is consequently often not known, even by aerobiologists themselves. This is a considerable problem, as local pollen data are an important tool for the prevention of allergic symptoms.
Objective
The aim of this study was to review pollen monitoring stations throughout the world and to create an interactive visualization of their distribution.
Methods
The method employed to collect information was based on: (a) a review of the recent and historical bibliography related to pollen and fungal spore monitoring, and (b) personal surveys of the managers of national and regional monitoring networks. The interactive application was developed using the R programming language.
Results
We have created an inventory of the active pollen and spore monitoring stations in the world. There are at least 879 active pollen monitoring stations in the world, most of which are in Europe (> 500). The prevalent monitoring method is based on the Hirst principle (> 600 stations). The inventory is visualised as an interactive and on‐line map. It can be searched, its appearance can be adjusted to the users’ needs and it is updated regularly, as new stations or changes to those that already exist can be submitted online.
Conclusions
The map shows the current situation of pollen and spore monitoring and facilitates collaboration among those individuals who are interested in pollen and spore counts. It might also help to improve the monitoring of biological particles up to the current level employed for non‐biological components.
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