scholarly journals The Role of G Protein Alpha Subunits in the Infection Process of the Gray Mold Fungus Botrytis cinerea

2001 ◽  
Vol 14 (11) ◽  
pp. 1293-1302 ◽  
Author(s):  
Christian Schulze Gronover ◽  
Daniela Kasulke ◽  
Paul Tudzynski ◽  
Bettina Tudzynski

To identify signal transduction pathways of the gray mold fungus Botrytis cinerea involved in host infection, we used heterologous hybridization and a polymerase chain reaction (PCR)-based approach to isolate two genes (bcg1 and bcg2) encoding α subunits of heterotrimeric GTP-binding proteins. Both genes have homologues in other fungi: bcg1 is a member of the Gαi class, whereas bcg2 has similarities to the magC gene of Magnaporthe grisea and the gna-2 gene of Neurospora crassa. Reverse-transcription (RT)-PCR experiments showed clearly that both genes are expressed at very early stages in infected bean leaves. Gene replacement experiments were performed for both genes. bcg1 null mutants differ in colony morphology from the wild-type strain, do not secrete extracellular proteases, and show clearly reduced pathogenicity on bean and tomato. Conidia germination and penetration of plant tissue is not disturbed in bcg1 mutants, but the infection process stops after formation of primary lesions. In contrast, bcg2 mutants show wild-type colony morphology in axenic culture and are only slightly reduced in pathogenicity. Complementation of bcg1 mutants with the wild-type gene copy led to the full recovery of colony morphology, protease secretion, and pathogenicity on both host plants. Application of exogenous cyclic AMP restored the wild-type growth pattern of bcg1 mutants, but not the protease secretion, implicating an essential role of BCG1 in different signaling pathways.

2000 ◽  
Vol 13 (7) ◽  
pp. 724-732 ◽  
Author(s):  
Li Zheng ◽  
Mathew Campbell ◽  
Jennifer Murphy ◽  
Stephen Lam ◽  
Jin-Rong Xu

In Magnaporthe grisea, a well-conserved mitogen-activated protein (MAP) kinase gene, PMK1, is essential for fungal pathogenesis. In this study, we tested whether the same MAP kinase is essential for plant infection in the gray mold fungus Botrytis cinerea, a necrotrophic pathogen that employs infection mechanisms different from those of M. grisea. We used a polymerase chain reaction-based approach to isolate MAP kinase homologues from B. cinerea. The Botrytis MAP kinase required for pathogenesis (BMP) MAP kinase gene is highly homologous to the M. grisea PMK1. BMP1 is a single-copy gene. bmp1 gene replacement mutants produced normal conidia and mycelia but were reduced in growth rate on nutrient-rich medium. bmp1 mutants were nonpathogenic on carnation flowers and tomato leaves. Re-introduction of the wild-type BMP1 allele into the bmp1 mutant restored both normal growth rate and pathogenicity. Further studies indicated that conidia from bmp1 mutants germinated on plant surfaces but failed to penetrate and macerate plant tissues. bmp1 mutants also appeared to be defective in infecting through wounds. These results indicated that BMP1 is essential for plant infection in B. cinerea, and this MAP kinase pathway may be widely conserved in pathogenic fungi for regulating infection processes.


2005 ◽  
Vol 18 (6) ◽  
pp. 602-612 ◽  
Author(s):  
Verena Siewers ◽  
Muriel Viaud ◽  
Daniel Jimenez-Teja ◽  
Isidro G. Collado ◽  
Christian Schulze Gronover ◽  
...  

The micrographic phytopathogen Botrytis cinerea causes gray mold diseases in a large number of dicotyledonous crop plants and ornamentals. Colonization of host tissue is accompanied by rapid killing of plant cells ahead of the growing hyphen, probably caused by secretion of nonspecific phytotoxins, e.g., the sesquiterpene botrydial. Although all pathogenic strains tested so far had been shown to secrete botrydial and although the toxin causes comparable necrotic lesions as infection by the fungus, the role of botrydial in the infection process has not been elucidated so far. Here, we describe the functional characterization of bcbot1, encoding a P450 monooxygenase and provide evidence that it is involved in the botrydial pathway, i.e., it represents the first botrydial biosynthetic gene identified. We show that bcbot1 is expressed in planta and that expression in vitro and in planta is controlled by an α-subunit of a heterotrimeric GTP-binding protein, BCG1. Deletion of bcbot1 in three standard strains of B. cinerea shows that the effect on virulence (on several host plants) is strain-dependent; only deletion in one of the strains (T4) led to reduced virulence.


2021 ◽  
Vol 22 (4) ◽  
pp. 1694
Author(s):  
Jiao Sun ◽  
Chen-Hao Sun ◽  
Hao-Wu Chang ◽  
Song Yang ◽  
Yue Liu ◽  
...  

Cyclophilin (Cyp) and Ca2+/calcineurin proteins are cellular components related to fungal morphogenesis and virulence; however, their roles in mediating the pathogenesis of Botrytis cinerea, the causative agent of gray mold on over 1000 plant species, remain largely unexplored. Here, we show that disruption of cyclophilin gene BcCYP2 did not impair the pathogen mycelial growth, osmotic and oxidative stress adaptation as well as cell wall integrity, but delayed conidial germination and germling development, altered conidial and sclerotial morphology, reduced infection cushion (IC) formation, sclerotial production and virulence. Exogenous cyclic adenosine monophosphate (cAMP) rescued the deficiency of IC formation of the ∆Bccyp2 mutants, and exogenous cyclosporine A (CsA), an inhibitor targeting cyclophilins, altered hyphal morphology and prevented host-cell penetration in the BcCYP2 harboring strains. Moreover, calcineurin-dependent (CND) genes are differentially expressed in strains losing BcCYP2 in the presence of CsA, suggesting that BcCyp2 functions in the upstream of cAMP- and Ca2+/calcineurin-dependent signaling pathways. Interestingly, during IC formation, expression of BcCYP2 is downregulated in a mutant losing BcJAR1, a gene encoding histone 3 lysine 4 (H3K4) demethylase that regulates fungal development and pathogenesis, in B. cinerea, implying that BcCyp2 functions under the control of BcJar1. Collectively, our findings provide new insights into cyclophilins mediating the pathogenesis of B. cinerea and potential targets for drug intervention for fungal diseases.


2021 ◽  
pp. 126731
Author(s):  
Md Kamaruzzaman ◽  
Ze Wang ◽  
Mingde Wu ◽  
Long Yang ◽  
Yongchao Han ◽  
...  

2008 ◽  
Vol 21 (6) ◽  
pp. 808-819 ◽  
Author(s):  
Nadja Segmüller ◽  
Leonie Kokkelink ◽  
Sabine Giesbert ◽  
Daniela Odinius ◽  
Jan van Kan ◽  
...  

Nicotinamide adenine dinucleotide (NADPH) oxidases have been shown to be involved in various differentiation processes in fungi. We investigated the role of two NADPH oxidases in the necrotrophic phytopathogenic fungus, Botrytis cinerea. The genes bcnoxA and bcnoxB were cloned and characterized; their deduced amino acid sequences show high homology to fungal NADPH oxidases. Analyses of single and double knock-out mutants of both NADPH oxidase genes showed that both bcnoxA and bcnoxB are involved in formation of sclerotia. Both genes have a great impact on pathogenicity: whereas bcnoxB mutants showed a retarded formation of primary lesions, probably due to an impaired formation of penetration structures, bcnoxA mutants were able to penetrate host tissue in the same way as the wild type but were much slower in colonizing the host tissue. Double mutants showed an additive effect: they were aberrant in penetration and colonization of plant tissue and, therefore, almost nonpathogenic. To study the structure of the fungal Nox complex in more detail, bcnoxR (encoding a homolog of the mammalian p67phox, a regulatory subunit of the Nox complex) was functionally characterized. The phenotype of ΔbcnoxR mutants is identical to that of ΔbcnoxAB double mutants, providing evidence that BcnoxR is involved in activation of both Bcnox enzymes.


2015 ◽  
Vol 28 (11) ◽  
pp. 1167-1180 ◽  
Author(s):  
Jani Kelloniemi ◽  
Sophie Trouvelot ◽  
Marie-Claire Héloir ◽  
Adeline Simon ◽  
Bérengère Dalmais ◽  
...  

Mature grapevine berries at the harvesting stage (MB) are very susceptible to the gray mold fungus Botrytis cinerea, while veraison berries (VB) are not. We conducted simultaneous microscopic and transcriptomic analyses of the pathogen and the host to investigate the infection process developed by B. cinerea on MB versus VB, and the plant defense mechanisms deployed to stop the fungus spreading. On the pathogen side, our genome-wide transcriptomic data revealed that B. cinerea genes upregulated during infection of MB are enriched in functional categories related to necrotrophy, such as degradation of the plant cell wall, proteolysis, membrane transport, reactive oxygen species (ROS) generation, and detoxification. Quantitative-polymerase chain reaction on a set of representative genes related to virulence and microscopic observations further demonstrated that the infection is also initiated on VB but is stopped at the penetration stage. On the plant side, genome-wide transcriptomic analysis and metabolic data revealed a defense pathway switch during berry ripening. In response to B. cinerea inoculation, VB activated a burst of ROS, the salicylate-dependent defense pathway, the synthesis of the resveratrol phytoalexin, and cell-wall strengthening. On the contrary, in infected MB, the jasmonate-dependent pathway was activated, which did not stop the fungal necrotrophic process.


2012 ◽  
Vol 25 (4) ◽  
pp. 481-495 ◽  
Author(s):  
S. Giesbert ◽  
J. Schumacher ◽  
V. Kupas ◽  
J. Espino ◽  
N. Segmüller ◽  
...  

Agrobacterium tumefaciens–mediated transformation (ATMT) was used to generate an insertional mutant library of the gray mold fungus Botrytis cinerea. From a total of 2,367 transformants, 68 mutants showing significant reduction in virulence on tomato and bean plants were analyzed in detail. As reported for other fungal ATMT libraries, integrations were mostly single copy, occurred preferentially in noncoding (regulatory) regions, and were frequently accompanied by small deletions of the target sequences and loss of parts of the border sequence. Two T-DNA integration events that were found to be linked to virulence were characterized in more detail: a catalytic subunit of a PP2A serine/threonine protein phosphatase (BcPP2Ac) and the SPT3 subunit of a Spt-Ada-Gcn5-acetyltransferase (SAGA-like) transcriptional regulator complex. Gene replacement and silencing approaches revealed that both Bcpp2Ac and SPT3 are crucial for virulence, growth, and differentiation as well as for resistance to H2O2 in B. cinerea.


2020 ◽  
Author(s):  
Zhexin Li ◽  
Jian-Bin Lan ◽  
Yi-Qing Liu ◽  
Li-Wang Qi ◽  
Jianmin Tang

Abstract Background: Elucidation of the regulatory mechanism of kiwifruit response to gray mold disease caused by Botrytis cinerea can provide the basis for its molecular breeding to impart resistance against this disease. In this study, 'Hongyang' kiwifruit served as the experimental material; the TOPLESS/TOPLESS-RELATED (TPL/TPR) co-repressor gene AcTPR2 was cloned into a pTRV2 vector (AcTPR2-TRV) and the virus-induced gene silencing technique was used to establish the functions of the AcTPR2 gene in kiwifruit resistance to Botrytis cinerea.Results: Virus-induced silencing of AcTPR2 enhanced the susceptibility of kiwifruit to Botrytis cinerea. Defensive enzymes such as superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and phenylalanine ammonia-lyase (PAL) and endogenous phytohormones such as indole acetic acid (IAA), gibberellin (GA3), abscisic acid (ABA), and salicylic acid (SA) were detected. Kiwifruit activated these enzymes and endogenous phytohormones in response to pathogen-induced stress and injury. The expression levels of the IAA signaling genes—AcNIT, AcARF1, and AcARF2—were higher in the AcTPR2-TRV treatment group than in the control. The IAA levels were higher and the rot phenotype was more severe in AcTPR2-TRV kiwifruits than that in the control. These results suggested that AcTPR2 downregulation promotes expression of IAA and IAA signaling genes and accelerates postharvest kiwifruit senescence. Further, Botrytis cinerea dramatically upregulated AcTPR2, indicating that AcTPR2 augments kiwifruit defense against pathogens by downregulating the IAA and IAA signaling genes.Conclusions: The results of the present study could help clarify the regulatory mechanisms of disease resistance in kiwifruit and furnish genetic resources for molecular breeding of kiwifruit disease resistance.


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