A cuticle-degrading protease (CDEP-1) of<i>Beauveria bassiana</i>enhances virulence

Zhang, Yongjun; Feng, Ming‐Guang; Fan, Yanhua; Luo, Zhibing; Yang, Xingyong; Wu, Di; Pei, Yan

doi:10.1080/09583150802082239

Cited by 52 publications

(44 citation statements)

References 28 publications

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“…Similarly, a MAPK suppresses the expression of cuticle-degrading enzyme encoding genes related to mycoparasitism in Trichoderma virens (28). However, disruption of Bbmpk1 in B. bassiana did not influence expression of two insect cuticle-degrading enzymes, a Pr1-like protease, Cdep1, and an secreted chitnase, Bbchit1, both of which are important virulence factors (8,52). The results suggest that expression of cuticle-degrading enzymes in B. bassiana is under the control of a different regulatory mechanism.…”

Section: Discussionmentioning

confidence: 99%

“…Thus far, only a few genes involved in the infection processes of B. bassiana have been identified. Most notably, a number of cuticle degrading enzymes and their genes have been characterized (1,8,52). In addition, two nonribosomal peptide synthetase (NRPS) encoding genes bbBeas and bbBsls, responsible for the synthesis of the insecticidal virulence factors beauvericin and bassianolide, respectively, have been recently identified (49,50).…”

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confidence: 99%

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Requirement of a Mitogen-Activated Protein Kinase for Appressorium Formation and Penetration of Insect Cuticle by the Entomopathogenic Fungus Beauveria bassiana

Zhang

Jiang

et al. 2010

Appl Environ Microbiol

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Beauveria bassiana is an important insect-pathogenic fungus that invades insects by direct penetration of the host cuticle. To delineate the molecular mechanisms involved in fungal infection, a mitogen-activated protein kinase (MAPK) gene, Bbmpk1, which encodes a YERK1 family MAPK was isolated and characterized. Targeted gene disruption of Bbmpk1 resulted in a complete loss of virulence when applied topically to host insects but did not affect growth of the fungus when conidia were injected directly into the hemocoel. Hyphae of the mutant strain growing in the insect hemocoel were unable to penetrate the cuticle growing outwards and consequently failed to sporulate on the cadaver surface. These data suggest that BbMPK1 is essential for penetration of the insect cuticle both from the outside and from the inside-out in order to escape and disperse from the host. Inactivation of BbMPK1 also caused a significant decrease in fungal adhesion to insect cuticles and eliminated their ability to form appressoria. In order to identify downstream genes regulated by BbMPK1, a suppressive subtractive hybridization (SSH) library was generated comparing mutant and wild-type transcripts isolated during appressorium formation. Thirty-one genes screened from the SSH library were determined to be expressed in the wild-type strain but either significantly reduced or not expressed in the mutant. Ten genes showed high or medium similarity to known protein encoding genes, including proteins involved in cell surface hydrophobicity, lipid metabolism, microtubule dynamics, mitochondrial electron transport, chromatin remodeling, transcription, rRNA processing, small nucleolar RNA accumulation, oxidation of aldehydes, translation, and likely other cellular processes.

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Section: Discussionmentioning

confidence: 99%

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confidence: 99%

Requirement of a Mitogen-Activated Protein Kinase for Appressorium Formation and Penetration of Insect Cuticle by the Entomopathogenic Fungus Beauveria bassiana

Zhang

Jiang

et al. 2010

Appl Environ Microbiol

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“…The mode of action of these fungi is through germination of conidia that adheres to the outer surface of target insect cuticle producing germ tube that can penetrate the cuticle towards the insect hemocoel. Penetrating germ tube multiplies forming mycelium in the interior portion causing eventually death of the infected insect (Pedrini et al 2007;Zhang et al 2008;Stephou et al 2012;Ortiz-Urquiza and Keyhani 2013). On the cadavers of dead insects due to infection with EPF, the internal mycelium penetrates the cuticle to the outside then grows on the cuticle surface producing large quantity of conidia at favorable conditions of temperature and relative humidity (Fig.…”

Section: Introductionmentioning

confidence: 99%

Efficacy of two species of entomopathogenic fungi against the stored-grain pest, Sitophilus granarius L. (Curculionidae: Coleoptera), via oral ingestion

Batta

2018

Egypt J Biol Pest Control

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Sitophilus granarius is a serious stored-grain insect that can destroy the whole grain of cereal crops. The present research demonstrated that two species of entomopathogenic fungi (EPF), Beauveria bassiana and Metarhizium anisoplidae, killed the treated adults of S. granarius when applied via oral ingestion. Mortality of S. granarius was shown by growth and development of the ingested conidia in the insect gut causing death of infected insects. During bioassays, the fungus conidia were mixed with wheat flour then provided to the insects for feeding on the mixture for 24 h. The insects were surface-treated with a contact fungicide (Merpan®) to kill the external conidia that could penetrate the cuticle and develop to kill the infected insects. Results indicated that the most effective ratio of mixing fungus conidia with the wheat flour was 0.1:2.0 (g/g) where this ratio should contain 2.75 × 10 8 conidia/g of M. anisopliae mixture or 2.6 × 10 8 conidia/g of B. bassiana mixture. Ingested conidia of each fungus caused a first mortality of S. granarius adults after 10 and 12 days of B. bassiana and M. anisopliae treatments, respectively. They also caused 50% mortality after 2.787 and 3.047 weeks of treatments for the same fungi, respectively. The novelty of this research is in adjusting and applying a technique of disinfection of insect cuticle with a fungicide and then verifying the presence of applied fungi in the infected insects. The practical application of this method was discussed.

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“…Samples were incubated at 25°C for 30 min, and the absorbance at 490 nm (A 490 ) was measured. One unit of PO activity was defined as a change in the A 490 of 0.01 after 30 min, as described previously (27). PO activity was determined in insects subjected to the following treatments: 2 l (1 ϫ 10 7 conidia/ml) of wild-type and Bb:: S43Ac conidial suspensions prepared in 0.05% Tween 80 was injected into the hemocoel of G. mellonella larvae, with injections of 0.05% Tween 80 used as controls.…”

Section: Methodsmentioning

confidence: 99%

“…Genetic engineering has become a powerful tool to improve fungal performance (20)(21)(22)(23), and the (over)expression of a variety of cuticle-degrading enzymes in M. anisopliae and/or B. bassiana, including chitinases, proteases, and chitinase-protease hybrids, has led to improvements in the virulence of these fungi (24)(25)(26)(27). More recently, small peptides, including trypsin-modulating oostatic factor (TMOF) from the mosquito Aedes aegypti and pheromone biosynthesis-activating neuropeptide (PBAN) from the fire ant Solenopsis invicta, were expressed in B. bassiana and resulted in increased virulence against their respective targets (28,29).…”

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confidence: 99%

Expression of a Toll Signaling Regulator Serpin in a Mycoinsecticide for Increased Virulence

Yang

Keyhani

Tang

et al. 2014

Appl Environ Microbiol

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bSerpins are ubiquitously distributed serine protease inhibitors that covalently bind to target proteases to exert their activities. Serpins regulate a wide range of activities, particularly those in which protease-mediated cascades are active. The Drosophila melanogaster serpin Spn43Ac negatively controls the Toll pathway that is activated in response to fungal infection. The entomopathogenic fungus Beauveria bassiana offers an environmentally friendly alternative to chemical pesticides for insect control. However, the use of mycoinsecticides remains limited in part due to issues of efficacy (low virulence) and the recalcitrance of the targets (due to strong immune responses). Since Spn43Ac acts to inhibit Toll-mediated activation of defense responses, we explored the feasibility of a new strategy to engineer entomopathogenic fungi with increased virulence by expression of Spn43Ac in the fungus. Compared to the 50% lethal dose (LD 50 ) for the wild-type parent, the LD 50 of B. bassiana expressing Spn43Ac (strain Bb::S43Ac-1) was reduced ϳ3-fold, and the median lethal time against the greater wax moth (Galleria mellonella) was decreased by ϳ24%, with the more rapid proliferation of hyphal bodies being seen in the host hemolymph. In vitro and in vivo assays showed inhibition of phenoloxidase (PO) activation in the presence of Spn43Ac, with Spn43Ac-mediated suppression of activation by chymotrypsin, trypsin, laminarin, and lipopolysaccharide occurring in the following order: chymotrypsin and trypsin > laminarin > lipopolysaccharide. Expression of Spn43Ac had no effect on the activity of the endogenous B. bassianaderived cuticle-degrading protease (CDEP-1). These results expand our understanding of Spn43Ac function and confirm that suppression of insect immune system defenses represents a feasible approach to engineering entomopathogenic fungi for greater efficacy.

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A cuticle-degrading protease (CDEP-1) ofBeauveria bassianaenhances virulence

Cited by 52 publications

References 28 publications

Requirement of a Mitogen-Activated Protein Kinase for Appressorium Formation and Penetration of Insect Cuticle by the Entomopathogenic Fungus Beauveria bassiana

Requirement of a Mitogen-Activated Protein Kinase for Appressorium Formation and Penetration of Insect Cuticle by the Entomopathogenic Fungus Beauveria bassiana

Efficacy of two species of entomopathogenic fungi against the stored-grain pest, Sitophilus granarius L. (Curculionidae: Coleoptera), via oral ingestion

Expression of a Toll Signaling Regulator Serpin in a Mycoinsecticide for Increased Virulence

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