The transmembrane protein AaSho1 is essential for appressorium formation and secondary metabolism but dispensable for vegetative growth in pear fungal Alternaria alternata

2021 ◽  
Author(s):  
Yongxiang Liu ◽  
Yongcai Li ◽  
Li Ma ◽  
Huiwen Deng ◽  
Yi Huang ◽  
...  
Keyword(s):  
Secondary Metabolism ◽  
Alternaria Alternata ◽  
Vegetative Growth ◽  
Transmembrane Protein ◽  
Appressorium Formation

scholarly journals G Protein α Subunit Genes Control Growth, Development, and Pathogenicity of Magnaporthe grisea

1997 ◽  
Vol 10 (9) ◽  
pp. 1075-1086 ◽  
Author(s):  
Shaohua Liu ◽  
Ralph A. Dean
Keyword(s):  
Neurospora Crassa ◽  
G Protein ◽  
Vegetative Growth ◽  
Magnaporthe Grisea ◽  
Cryphonectria Parasitica ◽  
Appressorium Formation ◽  
Α Subunit ◽  
Targeted Deletion ◽  
Control Growth ◽  
G Protein Α Subunit

Three G protein α subunit genes have been cloned and characterized from Magnaporthe grisea: magA is very similar to CPG-2 of Cryphonectria parasitica; magB is virtually identical to CPG-1 of Cryphonectria parasitica, to gna1 of Neurospora crassa, and to fadA of Emericella nidulans; and magC is most similar to gna2 of Neurospora crassa. Homologous recombination resulting in targeted deletion of magA had no effect on vegetative growth, conidiation, or appressorium formation. Deletion of magC reduced conidiation, but did not affect vegetative growth or appressorium formation. However, disruption of magB significantly reduced vegetative growth, conidiation, and appressorium formation. magB¯ transformants, unlike magA¯ and magC¯ transformants, exhibited a reduced ability to infect and colonize susceptible rice leaves. G protein α subunit genes are required for M. grisea mating. magB¯ transformants failed to form perithecia, whereas magA¯ and magC¯ transformants did not produce mature asci. These results suggest that G protein α subunit genes are involved in signal transduction pathways in M. grisea that control vegetative growth, conidiation, conidium attachment, appressorium formation, mating, and pathogenicity.

A novel role of ammonia in appressorium formation of Alternaria alternata (Fries) Keissler, a tobacco pathogenic fungus

2010 ◽  
Vol 117 (3) ◽  
pp. 112-116 ◽  
Author(s):  
W. J. Duan ◽  
X. Q. Zhang ◽  
T. Z. Yang ◽  
X. W. Dou ◽  
T. G. Chen ◽  
...  
Keyword(s):  
Alternaria Alternata ◽  
Pathogenic Fungus ◽  
Appressorium Formation

scholarly journals An LaeA- and BrlA-Dependent Cellular Network Governs Tissue-Specific Secondary Metabolism in the Human PathogenAspergillus fumigatus

mSphere ◽  
2018 ◽  
Vol 3 (2) ◽  
Author(s):  
Abigail L. Lind ◽  
Fang Yun Lim ◽  
Alexandra A. Soukup ◽  
Nancy P. Keller ◽  
Antonis Rokas
Keyword(s):  
Aspergillus Fumigatus ◽  
Secondary Metabolism ◽  
Filamentous Fungi ◽  
Vegetative Growth ◽  
Cellular Network ◽  
Asexual Development ◽  
Human Pathogen ◽  
Wild Type ◽  
Cellular Processes ◽  
Type Strains

ABSTRACTBiosynthesis of many ecologically important secondary metabolites (SMs) in filamentous fungi is controlled by several global transcriptional regulators, like the chromatin modifier LaeA, and tied to both development and vegetative growth. InAspergillusmolds, asexual development is regulated by the BrlA > AbaA > WetA transcriptional cascade. To elucidate BrlA pathway involvement in SM regulation, we examined the transcriptional and metabolic profiles of ΔbrlA, ΔabaA, and ΔwetAmutant and wild-type strains of the human pathogenAspergillus fumigatus. We find that BrlA, in addition to regulating production of developmental SMs, regulates vegetative SMs and the SrbA-regulated hypoxia stress response in a concordant fashion to LaeA. We further show that the transcriptional and metabolic equivalence of the ΔbrlAand ΔlaeAmutations is mediated by an LaeA requirement preventing heterochromatic marks in thebrlApromoter. These results provide a framework for the cellular network regulating not only fungal SMs but diverse cellular processes linked to virulence of this pathogen.IMPORTANCEFilamentous fungi produce a spectacular variety of small molecules, commonly known as secondary or specialized metabolites (SMs), which are critical to their ecologies and lifestyles (e.g., penicillin, cyclosporine, and aflatoxin). Elucidation of the regulatory network that governs SM production is a major question of both fundamental and applied research relevance. To shed light on the relationship between regulation of development and regulation of secondary metabolism in filamentous fungi, we performed global transcriptomic and metabolomic analyses on mutant and wild-type strains of the human pathogenAspergillus fumigatusunder conditions previously shown to induce the production of both vegetative growth-specific and asexual development-specific SMs. We find that the genebrlA, previously known as a master regulator of asexual development, is also a master regulator of secondary metabolism and other cellular processes. We further show thatbrlAregulation of SM is mediated bylaeA, one of the master regulators of SM, providing a framework for the cellular network regulating not only fungal SMs but diverse cellular processes linked to virulence of this pathogen.

scholarly journals AaPKAc Regulates Differentiation of Infection Structures Induced by Physicochemical Signals From Pear Fruit Cuticular Wax, Secondary Metabolism, and Pathogenicity of Alternaria alternata

2021 ◽  
Vol 12 ◽  
Author(s):  
Miao Zhang ◽  
Yongcai Li ◽  
Tiaolan Wang ◽  
Yang Bi ◽  
Rong Li ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Mutant Strain ◽  
Alternaria Alternata ◽  
Intracellular Camp ◽  
Pear Fruit ◽  
Appressorium Formation ◽  
Dependent Protein Kinase ◽  
Camp Content ◽  
Infection Structures ◽  
Dependent Protein

Alternaria alternata, the casual agent of black rot of pear fruit, can sense and respond to the physicochemical cues from the host surface and form infection structures during infection. To evaluate the role of cyclic AMP-dependent protein kinase (cAMP-PKA) signaling in surface sensing of A. alternata, we isolated and functionally characterized the cyclic adenosine monophosphate-dependent protein kinase A catalytic subunit gene (AaPKAc). Gene expression results showed that AaPKAc was strongly expressed during the early stages of appressorium formation on hydrophobic surfaces. Knockout mutants ΔAaPKAc were generated by replacing the target genes via homologous recombination events. We found that intracellular cAMP content increased but PKA content decreased in ΔAaPKAc mutant strain. Appressorium formation and infection hyphae were reduced in the ΔAaPKAc mutant strain, and the ability of the ΔAaPKAc mutant strain to recognize and respond to high hydrophobicity surfaces and different surface waxes was lower than in the wild type (WT) strain. In comparison with the WT strain, the appressorium formation rate of the ΔAaPKAc mutant strain on high hydrophobicity and fruit wax extract surface was reduced by 31.6 and 49.3% 4 h after incubation, respectively. In addition, AaPKAc is required for the hypha growth, biomass, pathogenicity, and toxin production of A. alternata. However, AaPKAc negatively regulated conidia formation, melanin production, and osmotic stress resistance. Collectively, AaPKAc is required for pre-penetration, developmental, physiological, and pathological processes in A. alternata.

scholarly journals Fungal jasmonate as a novel morphogenetic signal for pathogenesis

2021 ◽  
Author(s):  
Yingyao Liu ◽  
Martin Pagac ◽  
Fan Yang ◽  
Rajesh Narhari Patkar ◽  
Naweed I Naqvi
Keyword(s):  
Cyclic Amp ◽  
Jasmonic Acid ◽  
Vegetative Growth ◽  
Rice Blast ◽  
Pathogenic Fungi ◽  
Appressorium Formation ◽  
Epistasis Analysis ◽  
Delayed Initiation ◽  
Developmental Switch ◽  
Cyclic Amp Signaling

A key question that has remained unanswered is how pathogenic fungi switch from vegetative growth to infection-related morphogenesis during a disease cycle. Here, we identify a fungal oxylipin analogous to the well-known phytohormone jasmonic acid, as the principal morphogenesis signal responsible for such a developmental switch to pathogenicity in the rice-blast fungus Magnaporthe oryzae. We explored the molecular function(s) of such intrinsic jasmonic acid during pathogenic differentiation in M. oryzae via OPR1, which encodes a 12-Oxo-phytodienoic Acid Reductase essential for its biosynthesis. Loss of OPR1 led to prolonged vegetative growth, and a delayed initiation and improper development of infection structures in M. oryzae, reminiscent of phenotypes observed in mutants (e.g. pth11Δ and cpkAΔ) that are compromised for cyclic AMP signaling. Genetic- or chemical-complementation completely restored proper germ tube growth and appressorium formation in opr1Δ. Liquid chromatography mass spectrometry-based quantification revealed increased OPDA accumulation and a significant decrease in JA levels in the opr1Δ. Most interestingly, exogenous jasmonic acid also restored appressorium formation in the pth11Δ mutant that lacks G protein/cyclic AMP signaling. Epistasis analysis placed fungal jasmonate upstream of the cyclic AMP signaling in rice blast. Lastly, we show that intrinsic jasmonate orchestrates the cessation of vegetative phase and initiates pathogenic development via a regulatory interaction with the cyclic AMP cascade and redox signaling in rice blast.

Spore germination and appressorium formation in the entomopathogenic Alternaria alternata

2002 ◽  
Vol 106 (11) ◽  
pp. 1349-1359 ◽  
Author(s):  
Panayotis Hatzipapas ◽  
Katerina Kalosak ◽  
Alexia Dara ◽  
Christos Christias
Keyword(s):  
Spore Germination ◽  
Alternaria Alternata ◽  
Appressorium Formation
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