Two nuclear effectors of the rice blast fungus modulate host immunity via transcriptional reprogramming

AbstractPathogens utilize multiple types of effectors to modulate plant immunity. Although many apoplastic and cytoplasmic effectors have been reported, nuclear effectors have not been well characterized in fungal pathogens. Here, we characterize two nuclear effectors of the rice blast pathogen Magnaporthe oryzae. Both nuclear effectors are secreted via the biotrophic interfacial complex, translocated into the nuclei of initially penetrated and surrounding cells, and reprogram the expression of immunity-associated genes by binding on effector binding elements in rice. Their expression in transgenic rice causes ambivalent immunity: increased susceptibility to M. oryzae and Xanthomonas oryzae pv. oryzae, hemibiotrophic pathogens, but enhanced resistance to Cochliobolus miyabeanus, a necrotrophic pathogen. Our findings help remedy a significant knowledge deficiency in the mechanism of M. oryzae–rice interactions and underscore how effector-mediated manipulation of plant immunity by one pathogen may also affect the disease severity by other pathogens.

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The overexpression of OsACBP5 protects transgenic rice against necrotrophic, hemibiotrophic and biotrophic pathogens

Scientific Reports ◽

10.1038/s41598-020-71851-9 ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Saritha Panthapulakkal Narayanan ◽

Shiu-Cheung Lung ◽

Pan Liao ◽

Clive Lo ◽

Mee-Len Chye

Keyword(s):

Pseudomonas Syringae ◽

Rice Blast ◽

Transgenic Arabidopsis ◽

Sheath Blight ◽

Xanthomonas Oryzae ◽

Deficient Mutant ◽

Class Iii ◽

Wild Type ◽

Enhanced Resistance ◽

Biotrophic Pathogens

Abstract The most devastating diseases in rice (Oryza sativa) are sheath blight caused by the fungal necrotroph Rhizoctonia solani, rice blast by hemibiotrophic fungus Magnaporthe oryzae, and leaf blight by bacterial biotroph Xanthomonas oryzae (Xoo). It has been reported that the Class III acyl-CoA-binding proteins (ACBPs) such as those from dicots (Arabidopsis and grapevine) play a role in defence against biotrophic pathogens. Of the six Arabidopsis (Arabidopsis thaliana) ACBPs, AtACBP3 conferred protection in transgenic Arabidopsis against Pseudomonas syringae, but not the necrotrophic fungus, Botrytis cinerea. Similar to Arabidopsis, rice possesses six ACBPs, designated OsACBPs. The aims of this study were to test whether OsACBP5, the homologue of AtACBP3, can confer resistance against representative necrotrophic, hemibiotrophic and biotrophic phytopathogens and to understand the mechanisms in protection. Herein, when OsACBP5 was overexpressed in rice, the OsACBP5-overexpressing (OsACBP5-OE) lines exhibited enhanced disease resistance against representative necrotrophic (R. solani & Cercospora oryzae), hemibiotrophic (M. oryzae & Fusarium graminearum) and biotrophic (Xoo) phytopathogens. Progeny from a cross between OsACBP5-OE9 and the jasmonate (JA)-signalling deficient mutant were more susceptible than the wild type to infection by the necrotroph R. solani. In contrast, progeny from a cross between OsACBP5-OE9 and the salicylic acid (SA)-signalling deficient mutant was more susceptible to infection by the hemibiotroph M. oryzae and biotroph Xoo. Hence, enhanced resistance of OsACBP5-OEs against representative necrotrophs appears to be JA-dependent whilst that to (hemi)biotrophs is SA-mediated.

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Tal2c Activates the Expression of OsF3H04g to Promote Infection as a Redundant TALE of Tal2b in Xanthomonas oryzae pv. oryzicola

International Journal of Molecular Sciences ◽

10.3390/ijms222413628 ◽

2021 ◽

Vol 22 (24) ◽

pp. 13628

Author(s):

Tao Wu ◽

Haimiao Zhang ◽

Yunya Bi ◽

Yue Yu ◽

Haifeng Liu ◽

...

Keyword(s):

Virulent Strain ◽

Xanthomonas Oryzae ◽

Transcription Activator ◽

Altered Expression ◽

Overexpression Line ◽

Dioxygenase Gene ◽

Highly Virulent ◽

Effector Binding ◽

Host Genes ◽

Increased Susceptibility

Xanthomonas oryzae delivers transcription activator-like effectors (TALEs) into plant cells to facilitate infection. Following economic principles, the redundant TALEs are rarely identified in Xanthomonas. Previously, we identified the Tal2b, which activates the expression of the rice 2-oxoglutarate-dependent dioxygenase gene OsF3H03g to promote infection in the highly virulent strain of X. oryzae pv. oryzicola HGA4. Here, we reveal that another clustered TALE, Tal2c, also functioned as a virulence factor to target rice OsF3H04g, a homologue of OsF3H03g. Transferring Tal2c into RS105 induced expression of OsF3H04g to coincide with increased susceptibility in rice. Overexpressing OsF3H04g caused higher susceptibility and less salicylic acid (SA) production compared to wild-type plants. Moreover, CRISPR–Cas9 system-mediated editing of the effector-binding element in the promoters of OsF3H03g or OsF3H04g was found to specifically enhance resistance to Tal2b- or Tal2c-transferring strains, but had no effect on resistance to either RS105 or HGA4. Furthermore, transcriptome analysis revealed that several reported SA-related and defense-related genes commonly altered expression in OsF3H04g overexpression line compared with those identified in OsF3H03g overexpression line. Overall, our results reveal a functional redundancy mechanism of pathogenic virulence in Xoc in which tandem Tal2b and Tal2c specifically target homologues of host genes to interfere with rice immunity by reducing SA.

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Salicylic acid is a key player of Arabidopsis autophagy mutant susceptibility to the necrotrophic bacterium Dickeya dadantii

Scientific Reports ◽

10.1038/s41598-021-83067-6 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Martine Rigault ◽

Sylvie Citerne ◽

Céline Masclaux-Daubresse ◽

Alia Dellagi

Keyword(s):

Fungal Pathogens ◽

Plant Immunity ◽

Nutrient Recycling ◽

Plant Tolerance ◽

Dickeya Dadantii ◽

Hormonal Balance ◽

Sa Signaling ◽

Increased Susceptibility ◽

Main Factor

AbstractAutophagy is a ubiquitous vesicular process for protein and organelle recycling in eukaryotes. In plant, autophagy is reported to play pivotal roles in nutrient recycling, adaptation to biotic and abiotic stresses. The role of autophagy in plant immunity remains poorly understood. Several reports showed enhanced susceptibility of different Arabidopsis autophagy mutants (atg) to necrotrophic fungal pathogens. Interaction of necrotrophic bacterial pathogens with autophagy is overlooked. We then investigated such interaction by inoculating the necrotrophic enterobacterium Dickeya dadantii in leaves of the atg2 and atg5 mutants and an ATG8a overexpressing line. Overexpressing ATG8a enhances plant tolerance to D. dadantii. While atg5 mutant displayed similar susceptibility to the WT, the atg2 mutant exhibited accelerated leaf senescence and enhanced susceptibility upon infection. Both phenotypes were reversed when the sid2 mutation, abolishing SA signaling, was introduced in the atg2 mutant. High levels of SA signaling in atg2 mutant resulted in repression of the jasmonic acid (JA) defense pathway known to limit D. dadantii progression in A. thaliana. We provide evidence that in atg2 mutant, the disturbed hormonal balance leading to higher SA signaling is the main factor causing increased susceptibility to the D. dadantii necrotroph by repressing the JA pathway and accelerating developmental senescence.

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The role of the MAP kinase−kinase protein StMKK1 in potato immunity to different pathogens

Horticulture Research ◽

10.1038/s41438-021-00556-5 ◽

2021 ◽

Vol 8 (1) ◽

Author(s):

Xiaokang Chen ◽

Wenbin Wang ◽

Pingping Cai ◽

Ziwei Wang ◽

Tingting Li ◽

...

Keyword(s):

Fungal Pathogens ◽

Plant Pathogens ◽

Plant Immunity ◽

Gray Mold ◽

Mitogen Activated Protein Kinase ◽

Necrotrophic Pathogen ◽

Mapk Cascades ◽

Molecular Pattern ◽

Mitogen Activated Protein ◽

Potato Resistance

AbstractMitogen-activated protein kinase (MAPK) cascades play important roles in plant immunity. Previously, we reported that the potato StMKK1 protein negatively regulates Nicotiana benthamiana resistance to Phytophthora infestans. However, the functions of StMKK1 in potato immunity are unknown. To investigate the roles of StMKK1 in potato resistance to different pathogens, such as the potato late-blight pathogen P. infestans, the bacterial wilt pathogen Ralstonia solanacearum, and the gray-mold fungal pathogen Botrytis cinerea, we generated StMKK1 transgenic lines and investigated the response of potato transformants to destructive oomycete, bacterial, and fungal pathogens. The results showed that overexpression and silencing of StMKK1 do not alter plant growth and development. Interestingly, we found that StMKK1 negatively regulated potato resistance to the hemibiotrophic/biotrophic pathogens P. infestans and R. solanacearum, while it positively regulated potato resistance to the necrotrophic pathogen B. cinerea. Further investigation showed that overexpression of StMKK1 suppressed potato pathogen-associated molecular pattern (PAMP)-triggered immunity (PTI) and salicylic acid (SA)-related responses, while silencing of StMKK1 enhanced PTI and SA-related immune responses. Taken together, our results showed that StMKK1 plays dual roles in potato defense against different plant pathogens via negative regulation of PTI and SA-related signaling pathways.

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OsGF14b Positively Regulates Panicle Blast Resistance but Negatively Regulates Leaf Blast Resistance in Rice

Molecular Plant-Microbe Interactions ◽

10.1094/mpmi-03-15-0047-r ◽

2016 ◽

Vol 29 (1) ◽

pp. 46-56 ◽

Cited By ~ 19

Author(s):

Qing Liu ◽

Jianyuan Yang ◽

Shaohong Zhang ◽

Junliang Zhao ◽

Aiqing Feng ◽

...

Keyword(s):

Salicylic Acid ◽

Rice Blast ◽

Blast Resistance ◽

Leaf Blast ◽

Biotic Stresses ◽

Enhanced Resistance ◽

Panicle Blast ◽

New Evidence ◽

Dependent Pathway ◽

Increased Susceptibility

Although 14-3-3 proteins have been reported to be involved in responses to biotic stresses in plants, their functions in rice blast, the most destructive disease in rice, are largely unknown. Only GF14e has been confirmed to negatively regulate leaf blast. We report that GF14b is highly expressed in seedlings and panicles during blast infection. Rice plants overexpressing GF14b show enhanced resistance to panicle blast but are susceptible to leaf blast. In contrast, GF14b-silenced plants show increased susceptibility to panicle blast but enhanced resistance to leaf blast. Yeast one-hybrid assays demonstrate that WRKY71 binds to the promoter of GF14b and modulates its expression. Overexpression of GF14b induces expression of jasmonic acid (JA) synthesis-related genes but suppresses expression of salicylic acid (SA) synthesis-related genes. In contrast, suppressed GF14b expression causes decreased expression of JA synthesis-related genes but activation of SA synthesis-related genes. These results suggest that GF14b positively regulates panicle blast resistance but negatively regulates leaf blast resistance, and that GF14b-mediated disease resistance is associated with the JA- and SA-dependent pathway. The different functions for 14-3-3 proteins in leaf and panicle blast provide new evidence that leaf and panicle blast resistance are controlled by different mechanisms.

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JA signal-mediated immunity of Dendrobium catenatum to necrotrophic Southern Blight pathogen

BMC Plant Biology ◽

10.1186/s12870-021-03134-y ◽

2021 ◽

Vol 21 (1) ◽

Author(s):

Cong Li ◽

Qiuyi Shen ◽

Xiang Cai ◽

Danni Lai ◽

Lingshang Wu ◽

...

Keyword(s):

Large Scale ◽

Plant Immunity ◽

Expression Patterns ◽

Protein Domain ◽

Functional Identification ◽

Necrotrophic Pathogen ◽

Southern Blight ◽

Meja Treatment ◽

Sclerotium Delphinii ◽

Large Scale Cultivation

Abstract Background Dendrobium catenatum belongs to the Orchidaceae, and is a precious Chinese herbal medicine. In the past 20 years, D. catenatum industry has developed from an endangered medicinal plant to multi-billion dollar grade industry. The necrotrophic pathogen Sclerotium delphinii has a devastating effection on over 500 plant species, especially resulting in widespread infection and severe yield loss in the process of large-scale cultivation of D. catenatum. It has been widely reported that Jasmonate (JA) is involved in plant immunity to pathogens, but the mechanisms of JA-induced plant resistance to S. delphinii are unclear. Results In the present study, the role of JA in enhancing D. catenatum resistance to S. delphinii was investigated. We identified 2 COI1, 13 JAZ, and 12 MYC proteins in D. catenatum genome. Subsequently, systematic analyses containing phylogenetic relationship, gene structure, protein domain, and motif architecture of core JA pathway proteins were conducted in D. catenatum and the newly characterized homologs from its closely related orchid species Phalaenopsis equestris and Apostasia shenzhenica, along with the well-investigated homologs from Arabidopsis thaliana and Oryza sativa. Public RNA-seq data were investigated to analyze the expression patterns of D. catenatum core JA pathway genes in various tissues and organs. Transcriptome analysis of MeJA and S. delphinii treatment showed exogenous MeJA changed most of the expression of the above genes, and several key members, including DcJAZ1/2/5 and DcMYC2b, are involved in enhancing defense ability to S. delphinii in D. catenatum. Conclusions The findings indicate exogenous MeJA treatment affects the expression level of DcJAZ1/2/5 and DcMYC2b, thereby enhancing D. catenatum resistance to S. delphinii. This research would be helpful for future functional identification of core JA pathway genes involved in breeding for disease resistance in D. catenatum.

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Mutations in Wheat Exhibiting Growth-Stage-Specific Resistance to Biotrophic Fungal Pathogens

Molecular Plant-Microbe Interactions ◽

10.1094/mpmi.2004.17.11.1242 ◽

2004 ◽

Vol 17 (11) ◽

pp. 1242-1249 ◽

Cited By ~ 6

Author(s):

Phil H. Smith ◽

John A. Howie ◽

Anthony J. Worland ◽

Rebecca Stratford ◽

Lesley A. Boyd

Keyword(s):

Fungal Pathogens ◽

Growth Stage ◽

Puccinia Striiformis ◽

Specific Resistance ◽

Yellow Rust ◽

Dominant Mutation ◽

Resistance Phenotype ◽

The Third ◽

Enhanced Resistance ◽

Seedling Leaf

Two mutants were isolated in wheat that showed enhanced resistance towards Puccinia striiformis f. sp. tritici, the fungal causal agent of yellow rust. The altered phenotype of I3-48 is due to a minimum of two mutation events, each showing a partial, additive effect, with one mutation segregating with a deletion on the long arm of chromosome 4D. In the case of I3-54, the enhanced resistance is due to a single, dominant mutation. In both mutants, the expression of the enhanced resistance is growth-stage specific. With I3-54, the full resistance phenotype is apparent from the third seedling leaf onwards, while with I3-48, a full resistance phenotype is only seen on the tenth and subsequent leaves. In addition to the enhanced resistance towards yellow rust, I3-48 also shows enhanced resistance towards brown rust, and I3-54 shows enhanced resistance to powdery mildew.

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Efficacy of Different Level of Systemic Fungicides on Management of Rice Blast at Baitadi, Nepal

The Geographic Base ◽

10.3126/tgb.v7i0.34267 ◽

2020 ◽

Vol 7 ◽

pp. 33-42

Author(s):

Ashok Acharya ◽

Prabin Ghimire ◽

Dhurba Raj Joshi ◽

Kishor Shrestha ◽

Govinda Sijapati ◽

...

Keyword(s):

Disease Severity ◽

Rice Blast ◽

Fungal Pathogens ◽

Block Design ◽

Rice Variety ◽

Disease Suppression ◽

Systemic Fungicide ◽

Disease Development ◽

Systemic Fungicides ◽

Different Levels

Rice blast (Pyriculariaoryzae Cavara) is one of the most devastating diseases affecting the rice crop in across the world. Systemic fungicides are used for the suppression of blast diseases caused by fungal pathogens. Propiconazole and Carbendazim are commercial chemical control products available in markets for the control of the fungal pathogen. An experiment was conducted to examine the effectiveness of systemic fungicide on suppression of rice blast incidence in farmers' field during wet seasons in 2016. The treatments consisted of the use of different levels of propiconazole and Carbendazim on ‘Rato Basmati’ a landrace rice variety. The experiments were arranged in a randomized complete block design with three replications. The disease was scored according to the standard scale developed by the International Rice Research Institute (IRRI). Disease severity and Area under Disease Progressive curve (AUDPC) was computed based on that scale score. Propiconazole and Carbendazim at different levels reduce disease development than no treatment (control). But its efficacy was not consistent. The magnitude of disease suppression by Propiconazole was high as compared to Carbendazim. The application of propiconazole at the rate of 1.5 ml effectively reduced disease severity and AUDPC at different dates. So propiconazole at the rate of 1.5 ml thrice at weekly intervals is effective to reduce the disease development

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The plant Mediator complex and its role in jasmonate signaling

Journal of Experimental Botany ◽

10.1093/jxb/erz233 ◽

2019 ◽

Vol 70 (13) ◽

pp. 3415-3424 ◽

Cited By ~ 12

Author(s):

Qingzhe Zhai ◽

Chuanyou Li

Keyword(s):

Rna Polymerase Ii ◽

Plant Hormone ◽

Plant Immunity ◽

Mediator Complex ◽

Transcriptional Coactivator ◽

Jasmonate Signaling ◽

Helix Loop Helix ◽

Transcriptional Reprogramming ◽

Genome Wide ◽

Ja Signaling

Abstract The Mediator complex is an essential, multisubunit transcriptional coactivator that is highly conserved in eukaryotes. Mediator interacts with gene-specific transcription factors, the RNA polymerase II transcriptional machinery, as well as several other factors involved in transcription, and acts as an integral hub to regulate various aspects of transcription. Recent studies of the plant Mediator complex have established that it functions in diverse aspects of plant development and fitness. Jasmonate (JA) is an oxylipin-derived plant hormone that regulates plant immunity and development. The basic helix–loop–helix transcription factor MYC2, which is a master regulator of JA signaling, orchestrates genome-wide transcriptional reprogramming of plant cells to coordinate defense- and growth-related processes. Here, we review the function of the plant Mediator complex in regulating JA signaling. We focus on the multifunctional Mediator subunit MED25, which emerges as an integrative hub for the transcriptional regulation of jasmonate signaling.

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A fungal effector targets a heat shock–dynamin protein complex to modulate mitochondrial dynamics and reduce plant immunity

Science Advances ◽

10.1126/sciadv.abb7719 ◽

2020 ◽

Vol 6 (48) ◽

pp. eabb7719

Author(s):

Guojuan Xu ◽

Xionghui Zhong ◽

Yanlong Shi ◽

Zhuo Liu ◽

Nan Jiang ◽

...

Keyword(s):

Transgenic Rice ◽

Protein Complex ◽

Fungal Pathogen ◽

Mitochondrial Dynamics ◽

Plant Immunity ◽

Mitochondrial Fission ◽

Plant Cells ◽

Related Protein ◽

Dnaj Protein ◽

Enhanced Resistance

Mitochondria are essential for animal and plant immunity. Here, we report that the effector MoCDIP4 of the fungal pathogen Magnaporthe oryzae targets the mitochondria-associated OsDjA9-OsDRP1E protein complex to reduce rice immunity. The DnaJ protein OsDjA9 interacts with the dynamin-related protein OsDRP1E and promotes the degradation of OsDRP1E, which functions in mitochondrial fission. By contrast, MoCDIP4 binds OsDjA9 to compete with OsDRP1E, resulting in OsDRP1E accumulation. Knockout of OsDjA9 or overexpression of OsDRP1E or MoCDIP4 in transgenic rice results in shortened mitochondria and enhanced susceptibility to M. oryzae. Overexpression of OsDjA9 or knockout of OsDRP1E in transgenic rice, in contrast, leads to elongated mitochondria and enhanced resistance to M. oryzae. Our study therefore reveals a previously unidentified pathogen-infection strategy in which the pathogen delivers an effector into plant cells to target an HSP40-DRP complex; the targeting leads to the perturbation of mitochondrial dynamics, thereby inhibiting mitochondria-mediated plant immunity.

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