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Dec 15
Read the Latest MPMI Editor’s Picks

 

A Lipopolysaccharide O-Antigen Synthesis Gene in Mesorhizobium huakuii Plays Differentiated Roles in Root Nodule Symbiotic Compatibility with Astragalus sinicus

Exploring the role of O-antigen in rhizobium–legume symbiosis, Zhide Tang and colleagues constructed a deletion mutant of MCHK_1752, a lipopolysaccharide (LPS) O-antigen polymerase gene in Mesorhizobium huakuii.

The inoculation of six Astragalus sinicus accessions with MCHK_1752 resulted in highly different symbiotic phenotypes in the accessions, indicating that this O-antigen synthesis gene affects the symbiotic compatibility between M. huakuii and A. sinicus during symbiotic nitrogen fixation.

This study provides new insights into the important role of LPS in the establishment of symbiotic nitrogen fixation systems and lays the foundation for further dissection of the molecular mechanism underlying rhizobium–legume symbiotic nitrogen fixation.

Putative NAD(P)-Binding Rossmann Fold Protein Is Involved in Chitosan-Induced Peroxidase Activity and Lipoxygenase Expression in Physcomitrium patens

Eeva Marttinen and colleagues screened part of the Physcomitrium patens mutant collection to elucidate the pathway of peroxidase activity in response to chitosan treatment.

Screening of 385 plants for reduced extracellular peroxidase activity enabled the identification of candidate plants with altered responses to chitosan treatment and ultimately led to the discovery of a Rossmann fold protein in P. patens.

This study suggests that the NAD(P)-binding Rossmann fold protein is involved as a novel player in the pathway leading to increased peroxidase activity after chitosan treatment and normal expression of lipoxygenase (LOX)—indicating a complex regulation of the defense response against pathogens in this species of moss.

Sep 18
Read the Newest MPMI Editor's Pick and Register for Upcoming Virtual Seminars

 

Elucidating the Obligate Nature and Biological Capacity of an Invasive Fungal Corn Pathogen

​Tar spot, caused by the fungal pathogen Phyllachora maydis, was first identified in the United States in 2015 and has since evolved into a major impediment to corn production. Joshua MacCready and colleagues used both genomic and transcriptomic data to provide foundational insights into how this pathogen is invading its plant host corn to ultimately complete its life cycle. This work is fundamental to understanding this host-pathogen interaction, as well as to developing control strategies for tar spot of corn.​


"What's New in MPMI!" is an open access series of live, online seminars that highlight trending MPMI papers presented by their authors. To increase accessibility and encourage global participation in the MPMI community, all virtual seminars are free to attend and open to anyone interested in molecular plant–microbe interactions.

Upcoming Seminars

November 13, 2023, at 7:00 p.m. CT

Hyelim Jeon and Cécile Segonzac will present "Manipulation of the Host Endomembrane System by Bacterial Effectors."

Register to attend this free presentation.

December 5, 2023, at 10:00 a.m. CT

Hasna Boubakri will present "A Nonspecific Lipid Transfer Protein with Potential Functions in Infection and Nodulation."

Register to attend this free presentation.

Recently Recorded Seminar

Sajjan Grover discusses his trending research that uncovered a dichotomous role of jasmonic acid in modulating sorghum defense against aphids. Watch this free presentation to learn more about the complexity of a plant–aphid interaction.

Watch Now!​

Jun 28
Catch Up on MPMI Editor's Picks and Virtual Seminars



NX Trichothecenes Are Required for
Fusarium graminearum Infection of Wheat

While the mycotoxin deoxynivalenol was previously shown to be a major virulence factor for Fusarium graminearum on wheat, the more recently discovered NX trichothecenes have not been characterized for their role in virulence. Guixia Hao and colleagues evaluated the role of NX trichothecenes in virulence using TRI5 gene disruptions that eliminated trichothecene biosynthesis during F. graminearum infection of wheat heads to show that the reduction in NX trichothecenes decreased both the initial infection of the wheat head and the subsequent spread compared to the wild-type strains. This work provides novel information on the mode of action of a new class of trichothecenes and exposes the TRI5 gene as a promising target for controlling Fusarium head blight of both wheat and barley.​

Arabidopsis Dynamin-Related Protein AtDRP2A Contributes to Late Flg22-Signaling and Effective Immunity Against Pseudomonas syringae Bacteria

Arabidopsis thaliana encodes two paralogs of the endocytic accessory protein DRP2. Gayani Enkanayake and colleagues further defined the functions of these two paralogs using the FLS2-flg22 system. Loss of AtDRP2A led to increased susceptibility to Pseudomonas syringae, and the effects resulting from the loss of AtDRP2A were distinct from the effects caused by the loss of AtDRP2B—with DRP2A being important for late flg22-mediated responses but not early responses, unlike DRP2B. This finding provides a new tool for investigating ligand-induced endocytosis of receptors in immunity.

The Potyviral Protein 6K2 from Turnip Mosaic Virus Increases Plant Resilience to Drought

Ved Prakash and colleagues demonstrated that Turnip mosaic virus (TuMV) can positively impact host plants by increasing plant survival under drought conditions. Their results show that at least three viral proteins contribute to enhanced drought tolerance in TuMV-infected Arabidopsis thaliana, with one of these proteins also conveying drought tolerance when expressed in Nicotiana benthamiana. This protein enhanced salicylic acid accumulation in both A. thaliana and N. benthamiana, demonstrating an ecological function in the plant during drought conditions.

On May 9, 2023, Janak Joshi, Amy Charkowski, and Adam Heuberger presented their MPMI Editor's Pick, "Protease Inhibitors from Solanum chacoense Inhibit Pectobacterium Virulence by Reducing Bacterial Protease Activity and Motility."

Watch the recorded presentation to learn more about proteomics, wild potato disease resistance, and the potential for protecting cultivated potatoes in the field. Watch now.

View all virtual seminars.​

Mar 21
Read the Latest MPMI Editor's Picks

Two Candidate Meloidogyne javanica Effector Genes, MjShKT and MjPUT3: A Functional Investigation of Their Roles in Regulating Nematode Parasitism

As one of the most destructive plant parasites, Meloidogyne root-knot nematodes infect thousands of plant species. Anil Kumar et al. used transcriptomic data from M. ja​vanica on tomato to identify two candidate M. javanica effectors potentially involved in nematode infection. Functional characterization of these effectors showed that MjShKT is involved in the inhibition of programmed cell death and that MjPUT3 may be involved in modifying root morphology—both of which improve the in planta fitness of the pathogen. This work provides another step toward understanding the important interaction between plants and nematodes.

Comparative Genomic Analysis of 31 Phytophthora Genomes Reveals Genome Plasticity and Horizontal Gene Transfer

Plant pathogens in the genus Phytophthora cause major economic losses globally. Brent Kronmiller and colleagues evaluated the relationships among 31 newly sequenced individual Phytophthora species using comparative genomics and transcriptomics and found variation in effector compliments, as well as predicted genes, that were likely involved in horizontal gene transfer events. This work provides a substantial resource for future studies involving Phytophthora species.

Effectors from a Bacterial Vector-Borne Pathogen Exhibit Diverse Subcellular Localization, Expression Profiles, and Manipulation of Plant Defense

To combat the phloem-limited 'Candidatus Liberibacter solanacearum' pathogen, Paola Reyes Caldas and colleagues determined its effector repertoire by predicting proteins secreted via the general secretory pathway across four different haplotypes. Additionally, they investigated effector localization in planta and profiled effector expression in the vector and host. Their results reveal that 'Candidatus Liberibacter solanacearum' effectors possess complex expression patterns, target diverse host organelles, and the majority are unable to suppress host immune responses. This research opens the door for identifying novel targets of these effectors to manage vector-borne diseases.​

Dec 21
Don't Miss the MPMI Editor's Picks from This Fall

September​

Protease Inhibitors from Solanum chacoense Inhibit Pectobacterium Virulence by Reducing Bacterial Protease Activity and Motility

Janak Joshi and colleagues identify protease inhibitors from wild potato that inhibit disease caused by bacterial Pectobacterium pathogens. These protease inhibitors can be used in potato breeding programs and may potentially have a much more immediate effect as purified proteins that can be used to manage Pectobacterium-caused disease.

October​​

Transcriptomic Identification of a Unique Set of Nodule-Specific Cysteine-Rich Peptides Expressed in the Nitrogen-Fixing Root Nodule of Astragalus sinicus

Nodule-specific cysteine-rich (NCR) peptides are targeted to the symbiosomes to regulate bacteroid differentiation. Feng Wei and colleagues identified NCR peptides from Astragalus sinicus and showed that AsNCRs expression depends on a rhizobial peptide transporter encoded by the BacA gene. Further, they established that AsNCR067 promotes rhizobial growth, whereas AsNCR083 expression in rhizobia disrupts late nodule development and bacteroid differentiation. This research highlights that NCR peptides are plant-encoded checkpoints for rhizobial differentiation in nodules and can be used as a tool to modify legume-rhizobia symbiosis.​

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A Promiscuity Locus Confers Lotus burttii Nodulation with Rhizobia from Five Different Genera

Why do some legumes interact only with one or two specialist rhizobia symbionts while others interact with many? Mohammad Zarrabian and colleagues identify a locus in Lotus burtii that determines its ability to interact with many different rhizobia strains. This study provides an opportunity to understand how host range and its restriction is controlled at a molecular level.​

Sep 20
Catch Up on MPMI Editor's Picks from This Summer!

June

Two AMP-Binding Domain Proteins from Rhizophagus irregularis Involved in Import of Exogenous Fatty Acids

M. Brands and P. Dörmann

Since it is unknown how arbuscular mycorrhizal fungi (AMF) take up host-derived fatty acids, which they need for nutrients, Mathias Brands and Peter Dörmann describe the characterization of two AMP-binding domain protein genes from Rhizophagus irregularis with sequence similarity to Saccharomyces cerevisiae fatty acid transporter 1 (FAT1). Their results suggest the two proteins might be involved in fatty acid import into the fungal arbuscules in colonized roots.​

July

Recognition of Microbe- and Damage-Associated Molecular Patterns by Leucine-Rich Repeat Pattern Recognition Receptor Kinases Confers Salt Tolerance in Plants

E. P.-I. Loo, Y. Tajima, K. Yamada, S. Kido, T. Hirase, H. Ariga, T. Fujiwara, K. Tanaka, T. Taji, I. E. Somssich, J. E. Parker, and Y. Saijo

Eliza Loo et al. find that activation of MAMP/DAMP signaling by a broad array of signals primes the plant to tolerate subsequent salt stress, demonstrating integration of abiotic and biotic signals via a conserved BAK1/BIK1 signaling pathway. This example of a biotic signaling promoting subsequent tolerance of an abiotic stress reveals the complexity of interactions of plants with their living and nonliving environment and may open new avenues to promote plant health in the field.​

August

Involvement of Arabidopsis Acyl Carrier Protein 1 in PAMP-Triggered Immunity

Z. Zhao, J. Fan, P. Yang, Z. Wang, S. Obol Opiyo, D. Mackey, and Y. Xia

Acyl carrier proteins (ACPs) are central components of fatty acid (FA) synthesis. Zhenzhen Zhao et al. show that ACP1 influences plant immunity by maintaining the balance of defense hormones jasmonic acid and salicylic acid, providing a direct link between FA and lipid biosynthesis to plant immune responses. This opens up the possibility of engineering disease-resistant plant varieties by modifying the expression levels of ACP1 in economically important crops.​

Jun 22
Explore Recent MPMI Editor's Picks!

​March

Two Related Picks from the MPMI Editors: We've studied rhizobia and legumes for a long time, and here we highlight two Editor's Picks that are beginning to address a whole new field: positive effects on nonhost plant growth and development by rhizobia. Both the Mercedes Schroeder et al. and the Casandra Hernández-Reyes et al. papers identify specific mechanisms by which symbiotic rhizobium bacteria promote the root growth of a nonhost, Arabidopsis, altering root architecture via auxin transport (Schroeder et al.) and modulating cell division and cell elongation via NLP-mediated nitrate signaling (Hernández-Reyes et al.).​

Bradyrhizobium japonicum IRAT FA3 Alters Arabidopsis thaliana Root Architecture via Regulation of Auxin Efflux Transporters PIN2, PIN3, PIN7, and ABCB19

Mercedes M. Schroeder, Melissa Y. Gomez, Nathan McLain, and Emma W. Gachomo

Plant root development changes in response to beneficial rhizobacteria. This MPMI paper by Schroeder et al. shows B. japonicum's influence on host transcriptional reprogramming during their beneficial interaction. Through bacterial association with knockout lines, plant auxin efflux transporters were identified as critical to developing the B. japonicum-modified root architecture.

NIN-Like Proteins: Interesting Players in Rhizobia-Induced Nitrate Signaling Response During Interaction with Non-Legume Host Arabidopsis thaliana

Casandra Hernández-Reyes, Elisabeth Lichtenberg, Jean Keller, Pierre-Marc Delaux, Thomas Ott, and Sebastian T. Schenk

As an essential macronutrient, nitrogen plays an important role in plant development and plant–microbe symbioses, including legume–rhizobia interactions. Hernández-Reyes et al. demonstrate that a nitrate-related NLP signaling pathway in Arabidopsis regulates rhizobium-induced lateral root growth and increased root hair length and density. The involvement of two NLP transcription factors in mediating this response and their similarity to known legume NLPs involved in nodule symbiosis suggests the response to rhizobia is a trait shared within that protein clade.

April​

Analysis of Outer Membrane Vesicles Indicates That Glycerophospholipid Metabolism Contributes to Early Symbiosis Between Sinorhizobium fredii HH103 and Soybean

Dongzhi Li, Ziqi Li, Jing Wu, Zhide Tang, Fuli Xie, Dasong Chen, Hui Lin, and Youguo Li

Gram-negative bacteria can produce outer membrane vesicles (OMVs), and most functional studies of OMVs have been focused on mammalian-bacterial interactions. Research on the OMVs of rhizobia is limited. In this work, Dhongzhi Li et al. isolated and purified OMVs from Sinorhizobium fredii HH103 under free-living conditions that were set as control (C-OMVs) and symbiosis-mimicking conditions that were induced by genistein (G-OMVs).

May

Synergistic Effects of a Root-Endophytic Trichoderma Fungus and Bacillus on Early Root Colonization and Defense Activation Against Verticillium longisporum in Rapeseed

Fatema Binte Hafiz, Narges Moradtalab, Simon Goertz, Steffen Rietz, Kristin Dietel, Wilfried Rozhon, Klaus Humbeck, Joerg Geistlinger, Günter Neumann, and Ingo Schellenberg

Rhizosphere-competent microbes often interact with plant roots and exhibit beneficial effects on plant performance. Numerous bacterial and fungal isolates are able to prime host plants for fast adaptive responses against pathogen attacks. The combined action of fungi and bacteria may lead to synergisms exceeding the effects of single strains. This study by Fatema Binte Hafiz et al. offers a perspective for the development of alternative and sustainable approaches to enhance the tolerance of rapeseed cultures against fungal infections.​

Mar 21
New MPMI Editor's Pick Announced!

Increasingly, new evidence is revealing variability in the epitope regions of bacterial flagellin, including in regions harboring the microbe-associated molecular patterns flg22 and flgII-28 that are recognized by the pattern recognition receptors. Learn more from Maria Malvino and colleagues in their paper "Influence of Flagellin Polymorphisms, Gene Regulation, and Responsive Memory on the Motility of Xanthomonas Species That Cause Bacterial Spot Disease of Solanaceous Plants."

Dec 20
In Case You Missed It—Editor's Picks from Recent Issues of MPMI

September

The Natural Antisense Transcript DONE40 Derived from the lncRNA ENOD40 Locus Interacts with SET Domain Protein ASHR3 during Inception of Symbiosis in Arachis hypogaea

Pritha Ganguly, Dipan Roy, Troyee Das, Anindya Kundu, Fabienne Cartieaux, Zhumur Ghosh, and Maitrayee DasGupta

The long noncoding RNA ENOD40 is required for cortical cell division during root nodule symbiosis (RNS) of legumes, although it is not essential for actinorhizal RNS. Ganguly et al. set out to understand whether ENOD40 is required for aeschynomenoid nodule formation in Arachis hypogaea. AhENOD40 expresses from chromosomes 5 (AhENOD40-1) and 15 (AhENOD40-2) during symbiosis, and RNA interference by these transcripts drastically affects nodulation, indicating the importance of ENOD40 in A. hypogaea.

​Metatranscriptomic Comparison of Endophytic and Pathogenic Fusarium–Arabidopsis Interactions Reveals Plant Transcriptional Plasticity​

Li Guo, Houlin Yu, Bo Wang, Kathryn Vescio, Gregory A. DeIulio, He Yang, Andrew Berg, Lili Zhang, Véronique Edel-Hermann, Christian Steinberg, H. Corby Kistler, and Li-Jun Ma​

Two strains of the fungus Fusarium oxysporum (Fo) share a core genome, but one is a beneficial endophyte while the other is a detrimental pathogen causing wilt and death. Guo et al. ​tried to tease apart why these two strains cause such opposite reactions, and more generally how plants respond differently to useful and harmful microbes, by exploring the interaction of these two strains with the model plant Arabidopsis.

October

Chitin Deacetylases Are Required for Epichloë festucae Endophytic Cell Wall Remodeling during Establishment of a Mutualistic Symbiotic Interaction with Lolium perenne

Nazanin Noorifar, Matthew S. Savoian, Arvina Ram, Yonathan Lukito, Berit Hassing, Tobias W. Weikert, Bruno M. Moerschbacher, and Barry Scott

A diverse set of microbes survives and thrives inside plants as endophytes, but we have little mechanistic understanding of these intimate associations. In their study, Noorifar et al. show the way in which an Epichloë endophyte remodels its cell wall, converting chitin to chitosan, to avoid detection by host defenses. Deletion mutants reveal an important role for chitin deacetylases in hyphal growth inside the plant.

November

Computational Structural Genomics Unravels Common Folds and Novel Families in the Secretome of Fungal Phytopathogen Magnaporthe oryzae

Kyungyong Seong and Ksenia V. Krasileva

Recent breakthroughs in protein structure modeling demonstrate the ability to predict protein folds without depending on homologous templates. In their study, Seong and Krasileva employed structure prediction methods on the secretome of the destructive fungal pathogen Magnaporthe oryzae. Out of 1,854 secreted proteins, they predicted the folds of 1,295 proteins (70%).

Mar 29
A Novel Role of Salt- and Drought-Induced RING 1 Protein in Modulating Plant Defense Against Hemibiotrophic and Necrotrophic Pathogens

​Many plant-encoded E3 ligases are known to be involved in plant defense. Ramu et al. report a novel role of E3 ligase SALT- AND DROUGHT-INDUCED RING FINGER1 (SDIR1) in plant immunity. Their research suggests that SDIR1 is a susceptibility factor and its activation or overexpression enhances disease caused by P. syringae pv. tomato DC3000 in Arabidopsis. 


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