Specialized and shared functions of the histidine kinase- and HOG1 MAP kinase-mediated signaling pathways in Alternaria alternata, a filamentous fungal pathogen of citrus

The ability of basic helix-loop-helix muscle regulatory factors (MRFs), such as MyoD, to convert nonmuscle cells to a myogenic lineage is regulated by numerous growth factor and oncoprotein signaling pathways. Previous studies have shown that H-Ras 12V inhibits differentiation to a skeletal muscle lineage by disrupting MRF function via a mechanism that is independent of the dimerization, DNA binding, and inherent transcriptional activation properties of the proteins. To investigate the intracellular signaling pathway(s) that mediates the inhibition of MRF-induced myogenesis by oncogenic Ras, we tested two transformation-defective H-Ras 12V effector domain variants for their ability to alter terminal differentiation. H-Ras 12V,35S retains the ability to activate the Raf/MEK/mitogen-activated protein (MAP) kinase cascade, whereas H-Ras 12V,40C is unable to interact directly with Raf-1 yet still influences other signaling intermediates, including Rac and Rho. Expression of each H-Ras 12V variant in C3H10T1/2 cells abrogates MyoD-induced activation of the complete myogenic program, suggesting that MAP kinase-dependent and -independent Ras signaling pathways individually block myogenesis in this model system. However, additional studies with constitutively activated Rac1 and RhoA proteins revealed no negative effects on MyoD-induced myogenesis. Similarly, treatment of Ras-inhibited myoblasts with the MEK1 inhibitor PD98059 revealed that elevated MAP kinase activity is not a significant contributor to the H-Ras 12V effect. These data suggest that an additional Ras pathway, distinct from the well-characterized MAP kinase and Rac/Rho pathways known to be important for the transforming function of activated Ras, is primarily responsible for the inhibition of myogenesis by H-Ras 12V.

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The Cek1 and Hog1 Mitogen-Activated Protein Kinases Play Complementary Roles in Cell Wall Biogenesis and Chlamydospore Formation in the Fungal Pathogen Candida albicans

Eukaryotic Cell ◽

10.1128/ec.5.2.347-358.2006 ◽

2006 ◽

Vol 5 (2) ◽

pp. 347-358 ◽

Cited By ~ 109

Author(s):

B. Eisman ◽

R. Alonso-Monge ◽

E. Román ◽

D. Arana ◽

C. Nombela ◽

...

Keyword(s):

Cell Wall ◽

Candida Albicans ◽

Map Kinase ◽

Fungal Pathogen ◽

Hog Pathway ◽

Cell Wall Biogenesis ◽

Chlamydospore Formation ◽

Mitogen Activated Protein ◽

Morphological Transitions ◽

Relationship Of

ABSTRACT The Hog1 mitogen-activated protein (MAP) kinase mediates an adaptive response to both osmotic and oxidative stress in the fungal pathogen Candida albicans. This protein also participates in two distinct morphogenetic processes, namely the yeast-to-hypha transition (as a repressor) and chlamydospore formation (as an inducer). We show here that repression of filamentous growth occurs both under serum limitation and under other partially inducing conditions, such as low temperature, low pH, or nitrogen starvation. To understand the relationship of the HOG pathway to other MAP kinase cascades that also play a role in morphological transitions, we have constructed and characterized a set of double mutants in which we deleted both the HOG1 gene and other signaling elements (the CST20, CLA4, and HST7 kinases, the CPH1 and EFG1 transcription factors, and the CPP1 protein phosphatase). We also show that Hog1 prevents the yeast-to-hypha switch independent of all the elements analyzed and that the inability of the hog1 mutants to form chlamydospores is suppressed when additional elements of the CEK1 pathway (CST20 or HST7) are altered. Finally, we report that Hog1 represses the activation of the Cek1 MAP kinase under basal conditions and that Cek1 activation correlates with resistance to certain cell wall inhibitors (such as Congo red), demonstrating a role for this pathway in cell wall biogenesis.

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Fungicidal management of Alternaria alternata (Fr.) Keissler causing blight of gerbera (Gerbera jamesonii H. Bolus ex J.D. Hook)

Journal of Applied and Natural Science ◽

10.31018/jans.v4i2.253 ◽

2012 ◽

Vol 4 (2) ◽

pp. 220-227 ◽

Cited By ~ 6

Author(s):

Dipak T. Nagrale ◽

Anil P. Gaikwad ◽

Sanjay Goswami ◽

Lalan Sharma

Keyword(s):

Disease Management ◽

Disease Control ◽

Alternaria Alternata ◽

Fungal Pathogen ◽

Management Practices ◽

Bordeaux Mixture ◽

Gerbera Jamesonii ◽

Leaf Spots ◽

Aerial Parts ◽

Blight Disease

Alternaria, the fungal pathogen has wide host range generally attacks the aerial parts of plants causing leaf spots and blights. Gerbera is a genus of ornamental flower plants. Gerbera plants are infected by many diseases. Different disease management practices are adopted in gerbera cultivation. The fungicidal management of Alternaria blight is one of the important strategies for the disease management in gerbera in polyhouse condition. In this study, preventive and curative fungicidal sprays were adopted for the management of blight disease in polyhouse. This study revealed that preventive fungicidal sprays were significant over curative fungicidal sprays for the management of Alternaria alternata blight of gerbera (Gerbera jamesonii H. Bolus ex J.D. Hook) in polyhouse. The preventive sprays made of Bordeaux mixture (0.6 %), tricyclazole (0.1%) and iprodione + carbendazim (0.1%) fungicides were found effective with 95.85 %, 96.59 % and 95.88 % disease control respectively, under polyhouse condition.

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MAP Kinase OsMEK2 and OsMPK1 Signaling for Ferroptotic Cell Death in Rice-Magnaporthe oryzae Interactions

10.1101/2020.06.26.174292 ◽

2020 ◽

Author(s):

Sarmina Dangol ◽

Raksha Singh ◽

Khoa Nam Nguyen ◽

Yafei Chen ◽

Juan Wang ◽

...

Keyword(s):

Cell Death ◽

Map Kinase ◽

Signaling Pathways ◽

Magnaporthe Oryzae ◽

Mapk Signaling ◽

Mitogen Activated Protein Kinase ◽

Microbial Pathogens ◽

Blast Disease ◽

Related Cell ◽

Mitogen Activated Protein

ABSTRACTMitogen-activated protein kinase (MAPK) signaling is required for plant cell death responses to invading microbial pathogens. Ferric ions and reactive oxygen species (ROS) accumulate in rice (Oryza sativa) tissues undergoing cell death during Magnaporthe oryzae infection. Here, we report that rice MAP kinase (OsMEK2 and OsMPK1) signaling cascades are involved in iron- and ROS-dependent ferroptotic cell death responses of rice to M. oryzae infection. OsMEK2 interacted with OsMPK1 in the cytoplasm, and OsMPK1 moved from the cytoplasm into the nucleus to bind to the OsWRKY90 transcription factor. OsMEK2 expression may trigger OsMPK1-OsWRKY90 signaling pathways in the nucleus. Avirulent M. oryzae infection in ΔOsmek2 mutant rice did not trigger iron and ROS accumulation and lipid peroxidation, and also downregulated OsMPK1, OsWRKY90, OsRbohB, and OsPR-1b expression. However, OsMEK2 overexpression induced ROS-and iron-dependent cell death in rice during M. oryzae infection. The downstream MAP kinase (OsMPK1) overexpression induced ROS- and iron-dependent ferroptotic cell death in the compatible rice-M. oryzae interaction. These data suggest that the OsMEK2-OsMPK1-OsWRKY90 signaling cascade is involved in the ferroptotic cell death in rice. The small-molecule inducer erastin triggered iron- and lipid ROS-dependent, but OsMEK2-independent, ferroptotic cell death in ΔOsmek2 mutant plants during M. oryzae infection. Disease-related cell death was lipid ROS-dependent and iron-independent in the ΔOsmek2 mutant plants. These combined results suggest that OsMEK2 and OsMPK1 expression positively regulates iron- and ROS-dependent ferroptotic cell death via OsMEK2-OsMPK1-OsWRKY90 signaling pathways, and blast disease (susceptibility)-related cell death was ROS-dependent but iron-independent in rice-M. oryzae interactions.

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