Emerging Research in Plant Cell Biology
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Emerging Research in Plant Cell Biology
A science editor's take on what's new and interesting in the plant kingdom.
Curated by Jennifer Mach
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Feedback regulation of COOLAIR expression controls seed dormancy and flowering time

Feedback regulation of COOLAIR expression controls seed dormancy and flowering time | Emerging Research in Plant Cell Biology | Scoop.it
Herbivores and an inopportune cold snap can destroy fragile plant seedlings. Plants control the dormancy of their seeds in anticipation of more favorable growth conditions. Chen and Penfield analyzed the molecular controls on seed dormancy in the model plant Arabidopsis thaliana. Two genes and an antisense RNA, known from the process of vernalization, integrate ambient temperature to control seed dormancy via their opposing configurations.

Science , this issue p. [1014][1]

[1]: /lookup/doi/10.1126/science.aar7361
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The Physcomitrella patens gene atlas project: large scale RNA‐seq based expression data (coll with IJPB, SPS)

The Physcomitrella patens gene atlas project: large scale RNA‐seq based expression data (coll with IJPB, SPS) | Emerging Research in Plant Cell Biology | Scoop.it
High throughput RNA sequencing (RNA‐seq) has recently become the method of choice to define and analyse transcriptomes. For the model moss Physcomitrella patens, although this method has been used to help the analysis of specific perturbations, no overall reference dataset has been established yet. In the framework of its Gene Atlas project, the Joint Genome Institute selected P. patens as a flagship genome, opening the way to generate the first comprehensive transcriptome dataset for this moss. The first round of sequencing described here is composed of 99 independent libraries spanning 34 different developmental stages and conditions. Upon dataset quality control and processing through read mapping, 28,509 of the 34,361 v3.3 gene models (83%) were detected to be expressed across the samples. Differentially expressed genes (DEGs) were calculated across the dataset to permit perturbation comparisons between conditions. The analysis of the three most distinct and abundant P. patens growth stages, protonema, gametophore and sporophyte, allowed us to define both general transcriptional patterns and stage‐specific transcripts. As an example of variation of physico‐chemical growth conditions, we detail here the impact of ammonium supplementation under standard growth conditions on the protonemal transcriptome. Finally, the cooperative nature of this project allowed us to analyse inter‐laboratory variation, as 13 different laboratories around the world provided samples. We compare the differences between single‐laboratory experiment replication with the comparison of the same experiment between different laboratories.

Via Loïc Lepiniec, Saclay Plant Sciences
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BRASSINOSTEROID-SIGNALING KINASE1 Phosphorylates MAPKKK5 to Regulate Immunity in Arabidopsis

BRASSINOSTEROID-SIGNALING KINASE1 Phosphorylates MAPKKK5 to Regulate Immunity in Arabidopsis | Emerging Research in Plant Cell Biology | Scoop.it
Arabidopsis (Arabidopsis thaliana) immune receptor FLAGELLIN SENSING2 (FLS2) rapidly forms a complex to activate pathogen-associated molecular pattern-triggered immunity (PTI) upon perception of the bacterial protein flagellin. The receptor-like cytoplasmic kinase BRASSINOSTEROID-SIGNALINGKINASE1 (BSK1) interacts with FLS2 and is critical for the activation of PTI. However, it is unknown how BSK1 transduces signals to activate downstream immune responses. We identified MEK Kinase5 (MAPKKK5) as a potential substrate of BSK1 by whole-genome phosphorylation analysis. In addition, we demonstrated that BSK1 interacts with and phosphorylates MAPKKK5. In the bsk1-1 mutant, the Ser-289 residue of MAPKKK5 was not phosphorylated as it was in the wild type. Similar to the bsk1 mutant, the mapkkk5 mutant displayed enhanced susceptibility to virulent and avirulent strains of the bacterial pathogen Pseudomonas syringae pv tomato DC3000, and to the fungal powdery mildew pathogen Golovinomyces cichoracearum. Phosphorylation of the Ser-289 residue is not involved in MAPKKK5-triggered cell death but is critical for MAPKKK5-mediated resistance to both bacterial and fungal pathogens. Furthermore, MAPKKK5 interacts with multiple MAPK kinases, including MKK1, MKK2, MKK4, MKK5, and MKK6. Overall, these results indicate that BSK1 regulates plant immunity by phosphorylating MAPKKK5 and suggest a direct regulatory mode of signaling from the immune complex to the MAPK cascade.
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A guide to sequence your favorite plant genomes

With the rapid development of sequencing technology and the plummeting cost, assembling whole genomes from non‐model plants will soon become routine for plant systematists and evolutionary biologists. Here we summarize and compare several of the latest genome sequencing and assembly approaches, offering a practical guide on how to approach a genome project. We also highlight certain precautions that need to be taken before investing time and money into a genome project.

Via Pierre-Marc Delaux
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Plant Vacuoles

Plant Vacuoles | Emerging Research in Plant Cell Biology | Scoop.it
Plant vacuoles are multifunctional organelles.Onthe one hand, most vegetative tissues develop lytic vacuoles that have a role in degradation.Onthe other hand, seed cells have two types of storage vacuoles: protein storage vacuoles (PSVs) in endosperm and embryonic cells and metabolite storage vacuoles in seed coats. Vacuolar proteins and metabolites are synthesized on the endoplasmic reticulum and then transported to the vacuoles via Golgi-dependent and Golgi-independent pathways. Proprotein precursors delivered to the vacuoles are converted into their respective mature forms by vacuolar processing enzyme, which also regulates various kinds of programmed cell death in plants. We summarize two types of vacuolar membrane dynamics that occur during defense responses: vacuolar membrane collapse to attack viral pathogens and fusion of vacuolar and plasma membranes to attack bacterial pathogens. We also describe the chemical defense against herbivores brought about by the presence of PSVs in the idioblast myrosin cell.

Via Loïc Lepiniec, Saclay Plant Sciences
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The Monocot-Specific Receptor-like Kinase SDS2 Controls Cell Death and Immunity in Rice

The Monocot-Specific Receptor-like Kinase SDS2 Controls Cell Death and Immunity in Rice | Emerging Research in Plant Cell Biology | Scoop.it
Programmed cell death (PCD) plays critical roles in plant immunity but must be regulated to prevent excessive damage. The E3 ubiquitin ligase SPL11 negatively regulates PCD and immunity in plants. We show that SPL11 cell-death suppressor 2 (SDS2), an S-domain receptor-like kinase, positively regulates PCD and immunity in rice by engaging and regulating SPL11 and related kinases controlling defense responses. An sds2 mutant shows reduced immune responses and enhanced susceptibility to the blast fungus Magnaporthe oryzae. Conversely, SDS2 over-expression induces constitutive PCD accompanied by elevated immune responses and enhanced resistance to M. oryzae. SDS2 interacts with and phosphorylates SPL11, which in turn ubiquitinates SDS2, leading to its degradation. In addition, SDS2 interacts with related receptor-like cytoplasmic kinases, OsRLCK118/176, that positively regulate immunity by phosphorylating the NADPH oxidase OsRbohB to stimulate ROS production. Thus, a plasma membrane-resident protein complex consisting of SDS2, SPL11, and OsRLCK118/176 controls PCD and immunity in rice.

Via Suayib Üstün
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Ethylene induced plant stress tolerance by Enterobacter sp. SA187 is mediated by 2‐keto‐4‐methylthiobutyric acid production (IPS2, SPS)

Ethylene induced plant stress tolerance by Enterobacter sp. SA187 is mediated by 2‐keto‐4‐methylthiobutyric acid production (IPS2, SPS) | Emerging Research in Plant Cell Biology | Scoop.it
Author summary Plants as sessile organisms are facing multiple stresses during their lifetime. Among them, abiotic stresses, such as salt stress, can cause severe crop yield reduction, leading to food security issues in many regions of the world. In order to respond to growing food demands, especially in the context of the global climate change and increasing world population, it then becomes urgent to develop new strategies to yield crops more tolerant to abiotic stresses. One way to overcome these challenges is to take advantage of plant beneficial microbes, defined as plant growth promoting bacteria (PGPB). In this study, we report the beneficial effect of Enterobacter sp. SA187 on plant growth under salt stress conditions. SA187 increased the yield of the forage crop alfalfa when submitted to different saline irrigations in field trials. Moreover, using the model plant Arabidopsis thaliana, we demonstrate that SA187 mediates its beneficial activity by producing 2-keto-4-methylthiobutyric acid (KMBA), which modulates the plant ethylene signaling pathway. This study highlights a novel mechanism involved in plant-PGPB interaction, and proves that endophytic bacteria can be efficiently used to enhance yield of current crops under salt stress conditions.

Via Saclay Plant Sciences
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Extracellular vesicles as key mediators of plant–microbe interactions

Extracellular vesicles as key mediators of plant–microbe interactions | Emerging Research in Plant Cell Biology | Scoop.it
Extracellular vesicles (EVs) are lipid compartments capable of trafficking proteins, lipids, RNA and metabolites between cells. Plant cells have been shown to secrete EVs during immune responses, but virtually nothing is known about their formation, contents or ultimate function. Recently developed methods for isolating plant EVs have revealed that these EVs are enriched in stress response proteins and signaling lipids, and appear to display antifungal activity. Comparison to work on animal EVs, and the observation that host-derived small interfering RNAs and microRNAs can silence fungal genes, suggests that plant EVs may also mediate trans-kingdom RNA interference. Many fundamental questions remain, however, regarding how plant EVs are produced, how they move, and if and how they are taken up by target cells.
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An extracellular network of Arabidopsis leucine-rich repeat receptor kinases

The cells of multicellular organisms receive extracellular signals using surface receptors. The extracellular domains (ECDs) of cell surface receptors function as interaction platforms, and as regulatory modules of receptor activation1,2. Understanding how interactions between ECDs produce signal-competent receptor complexes is challenging because of their low biochemical tractability3,4. In plants, the discovery of ECD interactions is complicated by the massive expansion of receptor families, which creates tremendous potential for changeover in receptor interactions5. The largest of these families in Arabidopsis thaliana consists of 225 evolutionarily related leucine-rich repeat receptor kinases (LRR-RKs)5, which function in the sensing of microorganisms, cell expansion, stomata development and stem-cell maintenance6,7,8,9. Although the principles that govern LRR-RK signalling activation are emerging1,10, the systems-level organization of this family of proteins is unknown. Here, to address this, we investigated 40,000 potential ECD interactions using a sensitized high-throughput interaction assay3, and produced an LRR-based cell surface interaction network (CSILRR) that consists of 567 interactions. To demonstrate the power of CSILRR for detecting biologically relevant interactions, we predicted and validated the functions of uncharacterized LRR-RKs in plant growth and immunity. In addition, we show that CSILRR operates as a unified regulatory network in which the LRR-RKs most crucial for its overall structure are required to prevent the aberrant signalling of receptors that are several network-steps away. Thus, plants have evolved LRR-RK networks to process extracellular signals into carefully balanced responses.

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Extracellular ATP Acts on Jasmonate Signaling to Reinforce Plant Defense

Extracellular ATP Acts on Jasmonate Signaling to Reinforce Plant Defense | Emerging Research in Plant Cell Biology | Scoop.it
Damaged cells send various signals to stimulate defense responses. Recent identification and genetic studies of the plant purinoceptor, P2K1 (also known as DORN1), have demonstrated that extracellular ATP is a signal involved in plant stress responses, including wounding, perhaps to evoke plant defense. However, it remains largely unknown how extracellular ATP induces plant defense responses. Here, we demonstrate that extracellular ATP induces plant defense mediated through activation of the intracellular signaling of jasmonate (JA), a well-characterized defense hormone. In Arabidopsis ( Arabidopsis thaliana ) leaves, ATP pretreatment induced resistance against the necrotrophic fungus, Botrytis cinerea . The induced resistance was enhanced in the P2K1 receptor overexpression line, but reduced in the receptor mutant, dorn1 - 3 . Mining the transcriptome data revealed that ATP induces a set of JA-induced genes. In addition, the P2K1-associated coexpression network contains defense-related genes, including those encoding jasmonate ZIM-domain (JAZ) proteins, which play key roles as repressors of JA signaling. We examined whether extracellular ATP impacts the stability of JAZ1 in Arabidopsis. The results showed that the JAZ1 stability decreased in response to ATP addition in a proteasome-dependent manner. This reduction required intracellular signaling via second messengers—cytosolic calcium, reactive oxygen species, and nitric oxide. Interestingly, the ATP-induced JAZ1 degradation was attenuated in the JA receptor mutant, coi1 , but not in the JA biosynthesis mutant, aos , or upon addition of JA biosynthesis inhibitors. Immunoprecipitation analysis demonstrated that ATP increases the interaction between COI1 and JAZ1, suggesting direct cross talk between extracellular ATP and JA in intracellular signaling events. Taken together, these results suggest that extracellular ATP signaling directly impacts the JA signaling pathway to maximize plant defense responses.

Via Tatsuya Nobori
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Speed breeding is a powerful tool to accelerate crop research and breeding

Speed breeding is a powerful tool to accelerate crop research and breeding | Emerging Research in Plant Cell Biology | Scoop.it

The growing human population and a changing environment have raised significant concern for global food security, with the current improvement rate of several important crops inadequate to meet future demand1. This slow improvement rate is attributed partly to the long generation times of crop plants. Here, we present a method called ‘speed breeding’, which greatly shortens generation time and accelerates breeding and research programmes. Speed breeding can be used to achieve up to 6 generations per year for spring wheat (Triticum aestivum), durum wheat (T. durum), barley (Hordeum vulgare), chickpea (Cicer arietinum) and pea (Pisum sativum), and 4 generations for canola (Brassica napus), instead of 2–3 under normal glasshouse conditions. We demonstrate that speed breeding in fully enclosed, controlled-environment growth chambers can accelerate plant development for research purposes, including phenotyping of adult plant traits, mutant studies and transformation. The use of supplemental lighting in a glasshouse environment allows rapid generation cycling through single seed descent (SSD) and potential for adaptation to larger-scale crop improvement programs. Cost saving through light-emitting diode (LED) supplemental lighting is also outlined. We envisage great potential for integrating speed breeding with other modern crop breeding technologies, including high-throughput genotyping, genome editing and genomic selection, accelerating the rate of crop improvement.

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Extracellular ATP elicits DORN1-mediated RBOHD phosphorylation to regulate stomatal aperture

Extracellular ATP elicits DORN1-mediated RBOHD phosphorylation to regulate stomatal aperture | Emerging Research in Plant Cell Biology | Scoop.it
In addition to acting as a cellular energy source, ATP can also act as a damage-associated molecular pattern in both animals and plants. Stomata are leaf pores that control gas exchange and, therefore, impact critical functions such as photosynthesis, drought tolerance, and also are the preferred entry point for pathogens. Here we show the addition of ATP leads to the rapid closure of leaf stomata and enhanced resistance to the bacterial pathogen Psuedomonas syringae. This response is mediated by ATP recognition by the receptor DORN1, followed by direct phosphorylation of the NADPH oxidase RBOHD, resulting in elevated production of reactive oxygen species and stomatal closure. Mutation of DORN1 phosphorylation sites on RBOHD eliminates the ability of ATP to induce stomatal closure. The data implicate purinergic signaling via DORN1 in the control of stomatal aperture with important implications for the control of plant photosynthesis, water homeostasis, pathogen resistance, and ultimately yield.

Via Suayib Üstün, Tatsuya Nobori, Jim Alfano
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Sharing resources for mutual benefit: crosstalk between disciplines deepens the understanding of mycorrhizal symbioses across scales

Sharing resources for mutual benefit: crosstalk between disciplines deepens the understanding of mycorrhizal symbioses across scales | Emerging Research in Plant Cell Biology | Scoop.it
Mycorrhizal scientists from 53 countries gathered in the city of Prague from 30 July until 4 August 2017 for the 9th International Conference on Mycorrhiza (ICOM9). They came to discuss an ancient symbiosis based on the exchange of resources between plant and fungal partners, with many impacts on plant health (van der Heijden et al., 2015). Much like this mutualistic interaction, delegates from disparate disciplines united with a strong focus on integration and sharing of resources for mutual benefit. By exchanging knowledge among researchers from the fields of molecular biology, physiology and ecology, the participants of ICOM9 made a leap forward in our understanding of symbiotic structure and function at multiple scales (Fig. 1).


Via Jean-Michel Ané
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Bob Reeves's curator insight, December 14, 2017 2:49 PM
Would have loved to have been a fly on the wall at this conference. So may great insights become possible when the various science disciplines mingle and share their findings. Symbiosis?
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CLE peptide tri‐arabinosylation and peptide domain sequence composition are essential for SUNN‐dependent autoregulation of nodulation in Medicago truncatula 

CLE peptide tri‐arabinosylation and peptide domain sequence composition are essential for SUNN‐dependent autoregulation of nodulation in Medicago truncatula  | Emerging Research in Plant Cell Biology | Scoop.it
MtCLE12 and MtCLE13 encode CLAVATA3/EMBRYO‐SURROUNDING REGION RELATED (CLE) peptides which regulate autoregulation of nodulation (AON) in Medicago through the shoot receptor, SUNN (SUPER NUMERIC NODULES). Genetics suggests RDN1 (ROOT‐DETERMINED NODULATION 1) arabinosylates MtCLE12 to enable SUNN perception. The functional structures of MtCLE12 and MtCLE13 peptides, however, remain elusive.
We combined genetic and chemical synthesis approaches to determine if glyco‐modifications of three nodule‐expressed CLE peptides are essential for AON. We also examined how root and shoot applied AON‐CLEs inhibit nodulation.
MtCLE12, MtCLE13 and MtCLE42 peptides were synthesized with hydroxylation, mono‐arabinosylation or tri‐arabinosylation (TaP) at proline 7. Only MtCLE12‐TaP and MtCLE13‐TaP peptides induced AON in wild‐type (WT) and rdn1‐1, but not in sunn‐4. The application of MtCLE13‐TaP to cotyledons 1 d before rhizobial inoculation completely inhibited both rhizobial infection and nodulation. By contrast, MtCLE12‐TaP induced significant AON without abolishing rhizobial infection.
The results indicate that key CLE domain amino acids and TaP modifications to MtCLE12 and MtCLE13 are essential for SUNN‐dependent AON. We also show evidence that RDN1 does not tri‐arabinosylate MtCLE13. Finally, MtCLE13‐TaP can induce a strong AON response in shoots that inhibits the entire symbiotic processes in roots. We present a new model for AON in Medicago.

Via Jean-Michel Ané
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Natural variation within a species for traits underpinning C4 photosynthesis

Natural variation within a species for traits underpinning C4 photosynthesis | Emerging Research in Plant Cell Biology | Scoop.it
Engineering C4 photosynthesis into C3 crops could substantially increase their yield by alleviating photorespiratory losses. This objective is challenging because the C4 pathway involves complex modifications to the biochemistry, cell biology and anatomy of leaves. Forward genetics has provided limited insight into the mechanistic basis of these properties, and there have been no reports of significant quantitative intra-specific variation of C4 attributes that would allow trait mapping. Here, we show that accessions of the C4 species Gynandropsis gynandra collected from locations across Africa and Asia exhibit natural variation in key characteristics of C4 photosynthesis. Variable traits include bundle sheath size and vein density, gas exchange parameters, and carbon-isotope discrimination associated with the C4 state. Abundance of transcripts encoding core enzymes of the C4 cycle also showed significant variation. Traits relating to water use showed more quantitative variation than those associated with carbon assimilation. We propose that variation in these traits likely adapted the hydraulic system for increased water use efficiency rather than improving carbon fixation, indicating that selection pressure may drive C4 diversity in G. gynandra by modifying water use rather than photosynthesis. The accessions analyzed can be easily crossed and produce fertile offspring. Our findings therefore indicate that natural variation within this C4 species is sufficiently large to allow genetic mapping of key C4 traits and regulators.

Via Pierre-Marc Delaux
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BRI1 and BAK1 interact with G proteins and regulate sugar-responsive growth and development in Arabidopsis

BRI1 and BAK1 interact with G proteins and regulate sugar-responsive growth and development in Arabidopsis | Emerging Research in Plant Cell Biology | Scoop.it
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Via Tatsuya Nobori
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Genome Editing for Global Food Security - Trends Biotechnol (2017) 

Genome Editing for Global Food Security - Trends Biotechnol (2017)  | Emerging Research in Plant Cell Biology | Scoop.it

Global food security is increasingly challenging in light of population increase, the impact of climate change on crop production, and limited land available for agricultural expansion. Here we outline how genome editing provides excellent and timely methods to optimize crop plants, and argue the urgency for societal acceptance and support. 


A growing world population and dietary shifts associated with economic developmenti have resulted in increasing and changing demands for food. In addition to political and economic responses to these challenges, new agricultural technologies are required to minimize threats including climate change, and to fulfill increasing demands, for example, by improving sustainable development despite unfavorable conditions (i.e., soil degeneration, drought, flooding, and temperature extremes)... 


Genome editing is one of the most promising solutions for food security issues, especially in developing countries where local crop plant varieties are the mainstay... Global food security is an enormous challenge with multifaceted social and economic implications; it therefore requires enormous coordinated efforts within this century. 


While large-scale and complex agricultural production chains contribute extensively to satisfying the food supply in highly developed countries, these facilities are not equally available to less-developed nations. It is thus clear that precise crop optimization with regard to yield, nutrition balance, and plant fitness using genome editing would be a necessary strategy to address current and potential agricultural challenges, thereby securing the food supply: investment costs for farmers can be kept low while globally diverse threats can be addressed in parallel. 


Rapid developments in genome editing technologies will decrease the costs and time required to produce optimized crops in the future, and the broad adoption of genome editing technologies for crop optimization requires government support in setting up an updated regulatory framework, which should be guided by reasonable discussion with the public... 


While ethical standards and food security challenges tend to be regionally specific, the regulatory framework and legislation for gene-edited crops should follow scientific oversight, in addition to potential risk assessments and the needs of consumers and farmers on a global scale.


https://doi.org/10.1016/j.tibtech.2017.08.004




Via Alexander J. Stein
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Leaf nodule symbiosis: function and transmission of obligate bacterial endophytes - ScienceDirect

Leaf nodule symbiosis: function and transmission of obligate bacterial endophytes - ScienceDirect | Emerging Research in Plant Cell Biology | Scoop.it
Various plant species establish intimate symbioses with bacteria within their aerial organs. The bacteria are contained within nodules or glands often present in distinctive patterns on the leaves, and have been used as taxonomic marker since the early 20th century. These structures are present in very diverse taxa, including dicots (Rubiaceae and Primulaceae) and monocots (Dioscorea). The symbionts colonize the plants throughout their life cycles and contribute bioactive secondary metabolites to the association. In this review, we present recent progress in the understanding of these plant–bacteria symbioses, including the modes of transmission, distribution and roles of the symbionts.
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A single fungal MAP kinase controls plant cell-to-cell invasion by the rice blast fungus

A single fungal MAP kinase controls plant cell-to-cell invasion by the rice blast fungus | Emerging Research in Plant Cell Biology | Scoop.it
When the rice blast fungus enters a rice cell, the plasma membrane stays intact, so the rice cell remains viable. The fungus then moves to adjacent cells via plasmodesmata, the plant's intercellular channels. Sakulkoo et al. used a chemical genetic approach to selectively inhibit a single MAP (mitogen-activated protein) kinase, Pmk1, in the blast fungus. Inhibition of Pmk1 trapped the fungus within a rice cell. Pmk1 regulated the expression of a suite of effector genes involved in suppression of host immunity, allowing the fungus to manipulate plasmodesmal conductance. At the same time, Pmk1 regulated the fungus's hyphal constriction, which allows movement into new host cells.

Science , this issue p. [1399][1]

[1]: /lookup/doi/10.1126/science.aaq0892

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Plant elicitor peptides promote plant defences against nematodes in soybean - Lee - 2018 - Molecular Plant Pathology -

Plant elicitor peptides promote plant defences against nematodes in soybean - Lee - 2018 - Molecular Plant Pathology - | Emerging Research in Plant Cell Biology | Scoop.it
Plant elicitor peptides (Peps) are widely distributed among angiosperms, and have been shown to amplify immune responses in multiple plant families. Here, we characterize three Peps from soybean (Glycine max) and describe their effects on plant defences against two damaging agricultural pests, the root‐knot nematode (Meloidogyne incognita) and the soybean cyst nematode (Heterodera glycines). Seed treatments with exogenous GmPep1, GmPep2 or GmPep3 significantly reduced the reproduction of both nematodes. Pep treatment also protected plants from the inhibitory effects of root‐knot nematodes on above‐ground growth, and up‐regulated basal expression levels of nematode‐responsive defence genes. GmPep1 induced the expression of its propeptide precursor (GmPROPEP1), a nucleotide‐binding site leucine‐rich repeat protein (NBS‐LRR), a pectin methylesterase inhibitor (PMEI), Respiratory Burst Oxidase Protein D (RBOHD) and the accumulation of reactive oxygen species (ROS) in leaves. In addition, GmPep2 and GmPep3 seed treatments up‐regulated RBOHD expression and ROS accumulation in roots and leaves. These results suggest that GmPeps activate plant defences through systemic transcriptional reprogramming and ROS signalling, and that Pep seed treatments represent a potential strategy for nematode management.
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Effects of Bt cabbage pollen on the honeybee Apis mellifera L

Effects of Bt cabbage pollen on the honeybee Apis mellifera L | Emerging Research in Plant Cell Biology | Scoop.it

Honeybees may be exposed to insecticidal proteins from transgenic plants via pollen during their foraging activity. Assessing effects of such exposures on honeybees is an essential part of the risk assessment process for transgenic Bacillus thuringiensis (Bt) cabbage. Feeding trials were conducted in a laboratory setting to test for possible effects of Cry1Ba3 cabbage pollen on Italian-derived honeybees Apis mellifera L. Newly emerged A. mellifera were fed transgenic pollen, activated Cry1Ba3 toxin, pure sugar syrup (60% w/v sucrose solution), and non-transgenic cabbage pollen, respectively. Then the effects on survival, pollen consumption, weight, detoxification enzyme activity and midgut enzyme activity of A. mellifera were monitored. The results showed that there were no significant differences in survival, pollen consumption, weight, detoxification enzyme activity among all treatments. No significant differences in the activities of total proteolytic enzyme, active alkaline trypsin-like enzyme and weak alkaline trypsin-like enzyme were observed among all treatments. These results indicate that the side-effects of the Cry1Ba3 cabbage pollen on A. mellifera L. are unlikely.

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The quest for durable resistance

The quest for durable resistance | Emerging Research in Plant Cell Biology | Scoop.it
Agriculture transformed humans from hunter-gatherers into city dwellers. This was made possible through the domestication of crops, such as wheat and barley. Based on archaeological evidence ( 1 ), we know that our ancestors' crops were constantly plagued by disease, including rusts and mildews on cereals. During the 4th century BCE, Romans sacrificed red cattle, foxes, and dogs to the god Robigus in the belief that it would prevent epidemics of cereal rusts. Today, we understand that crop diseases are caused by plant pathogens. Cereal rusts are fungal pathogens that colonize foliar parts of the plant, such as the stem or leaf. The ability of these pathogens to infect a plant requires the suppression of the plant's immune system. The principal weapon used by pathogens to inhibit immunity are effectors, typically small secreted proteins. Plants recognize pathogens through immune receptors, including those that either directly or indirectly “perceive” pathogen effectors secreted into the plant ( 2 ). On pages 1604 and 1607 of this issue, Salcedo et al. ( 3 ) and Chen et al. ( 4 ), respectively, describe the identification of two effectors from the fungal pathogen Puccinia graminis f. sp. tritici , the causal agent of wheat stem rust. The discovery of these effectors represents a critical milestone for developing an approach to track and prevent the worldwide spread of the rusts of wheat ( 5 ) and improve our understanding of the biology of these devastating pathogens.

Via Pierre Gladieux, Niklaus Grunwald
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Nature's genetic screens: using genome‐wide association studies for effector discovery

Nature's genetic screens: using genome‐wide association studies for effector discovery | Emerging Research in Plant Cell Biology | Scoop.it
Understanding the biology of infections requires knowledge about the intricate molecular dialogue between plants and pathogens. Some components of this molecular dialogue are well-conserved across taxa and the interacting molecules can often be inferred by homology. Yet in all specialized plant-pathogen interactions, a substantial portion of the molecular dialogue is based on proteins that are unique to the pathosystem (e.g. most effector proteins). Identifying these proteins is very challenging because the pathogen often gained the genes encoding these proteins in the recent past and the proteins often share only minor similarities among pathogens. Yet the speed of pathogen evolution can be exploited to identify these crucial components of the molecular dialogue. Pathogen populations often harbor both virulent and avirulent strains, because the adaptation to exploit a new host genotype is not yet fixed within the species. Hence, genomic analyses can point to the genetic differences between the evolved (i.e. virulent) and the ancestral (i.e. avirulent) genotypes. The complication is though that most genetic differences between such groups of strains are unrelated to the actual gain in virulence. A technique that was recently invented to identify the mutations responsible for human genetic diseases provides a solution to this dilemma.
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A role for small RNA in regulating innate immunity during plant growth

A role for small RNA in regulating innate immunity during plant growth | Emerging Research in Plant Cell Biology | Scoop.it
Author summary In plants, nucleotide-binding (NB) leucine-rich repeat (LRR) receptors (NLR) mediate pathogen-specific effector triggered immunity and are widely used in breeding to generate pathogen-resistant crops. However, dysregulation of NLR expression can inhibit plant growth and how NLR expression and function are regulated in different stages of plant growth is poorly understood. Using a high-throughput sequencing and bioinformatics approach, we found an overall increase in NLR expression, but expression of NLR-targeting sRNA during plant growth was decreased. We also used resistance to tobacco mosaic virus (TMV) mediated by the resistance gene N as a model system to study the biological significance of growth regulation of NLR by miRNAs. We found that N-mediated TMV immunity strengthened and N transcript levels increased during plant maturation. Using genetic analysis, we showed that up-regulation of N was due to transcriptional down-regulation of the N-targeting miR6019/6020 cluster during plant growth. We also showed that sRNA-mediated growth regulation of N expression and function was conserved between tobacco and tomato plants. This study therefore reveals a role for miRNAs in regulating innate immunity during plant growth.

Via Yogesh Gupta, Tatsuya Nobori
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Stochastic gene expression in Arabidopsis thaliana

Stochastic gene expression in Arabidopsis thaliana | Emerging Research in Plant Cell Biology | Scoop.it
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Via Tatsuya Nobori
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