Increased Insect Virulence in
            <i>Beauveria bassiana</i>
            Strains Overexpressing an Engineered Chitinase

Fan, Yanhua; Fang, Weiguo; Guo, Shujuan; Pei, Xiaokun; Zhang, Yongjun; Xiao, Yazhong; Li, De-Mou; Jin, Kai; Bidochka, Michael; Pei, Yan

doi:10.1128/aem.01974-06

Cited by 196 publications

(128 citation statements)

References 31 publications

Supporting

Mentioning

117

Contrasting

Unclassified

Order By: Relevance

“…To test the virulence of fungal strains, adult aphids (M. persicae) were used for the bioassay. The bioassay was conducted as previously described (18). Fifty percent lethal concentrations (LC 50 s), confidence intervals, and values for other regression parameters were determined using the DPS program.…”

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Carboxylate Transporter Gene JEN1 from the Entomopathogenic Fungus Beauveria bassiana Is Involved in Conidiation and Virulence

Jin

Zhang

Fang

et al. 2010

Appl Environ Microbiol

Self Cite

View full text Add to dashboard Cite

Beauveria bassiana is an important entomopathogenic fungus widely used as a biological agent to control insect pests. A gene (B. bassiana JEN1 [BbJEN1]) homologous to JEN1 encoding a carboxylate transporter in Saccharomyces cerevisiae was identified in a B. bassiana transfer DNA (T-DNA) insertional mutant. Disruption of the gene decreased the carboxylate contents in hyphae, while increasing the conidial yield. However, overexpression of this transporter resulted in significant increases in carboxylates and decreased the conidial yield. BbJEN1 was strongly induced by insect cuticles and highly expressed in the hyphae penetrating insect cuticles not in hyphal bodies, suggesting that this gene is involved in the early stage of pathogenesis of B. bassiana. The bioassay results indicated that disruption of BbJEN1 significantly reduced the virulence of B. bassiana to aphids. Compared to the wild type, ⌬BbJEN1 alkalinized the insect cuticle to a reduced extent. The alkalinization of the cuticle is a physiological signal triggering the production of pathogenicity. Therefore, we identified a new factor influencing virulence, which is responsible for the alkalinization of the insect cuticle and the initiation of fungal pathogenesis in insects.Mycoinsecticides are considered promising biological control agents and alternatives or supplements to chemical pesticides (15). However, the dearth of physiological, genetic, and molecular knowledge of entomopathogenic fungi has retarded their widespread application.For mycoinsecticide improvement, greater attention and effort have been given to elucidate the mechanisms of fungal pathogenesis (13,14,18,20,29,49,50,51,52,53). Entomopathogenic fungi, e.g., Metarhizium anisopliae and Beauveria bassiana, invade their hosts by direct penetration of the host exoskeleton or cuticle. M. anisopliae and B. bassiana produce hydrophobic spores which contact and adhere to the insect cuticle (12). Once attached, the conidium germinates and the germ tubes differentiate into swollen infection structures called appressoria. The appressoria produce penetration pegs which penetrate the insect cuticle via cuticle-degrading enzymes (11,19,46) as well as mechanical pressure (24, 53). Hyphae proliferate within the hemocoel, emerge from inside the insect, and subsequently conidiate on the cadaver (15). However, much remains to be elucidated regarding the mechanisms of insect fungal pathogenesis.To obtain detailed knowledge of the mechanisms of fungal pathogenesis, a pool of B. bassiana transfer DNA (T-DNA) insertional mutants had been generated through an Agrobacterium-mediated-transformation method (21). A mutant, designated T12, characterized by the presence of more conidia, was isolated, and its flanking sequence was obtained by T-DNA tagging. The flanking fragment contained an open reading frame (ORF), which corresponded to a gene termed JEN1, encoding a transporter of carboxylates (http://www.ncbi.nlm .nih.gov/Blast.cgi). Organic acid transportation is important for the metabolism of almost all cells ...

show abstract

Section: Methodsmentioning

confidence: 99%

“…For mycoinsecticide improvement, greater attention and effort have been given to elucidate the mechanisms of fungal pathogenesis (13,14,18,20,29,49,50,51,52,53). Entomopathogenic fungi, e.g., Metarhizium anisopliae and Beauveria bassiana, invade their hosts by direct penetration of the host exoskeleton or cuticle.…”

mentioning

confidence: 99%

Carboxylate Transporter Gene JEN1 from the Entomopathogenic Fungus Beauveria bassiana Is Involved in Conidiation and Virulence

Jin

Zhang

Fang

et al. 2010

Appl Environ Microbiol

Self Cite

View full text Add to dashboard Cite

show abstract

“…Os métodos de inoculação ou aplicação mais utilizados são: pulverização sobre o inseto HIROSE, 2005;TALAEI-HASSANLOUI et al, 2007;FAN et al, 2007); mergulho ou imersão dos insetos em suspensão de fungo (ALMEIDA et al, 2009); tratamento da superfície (solo ou folha) com a suspensão de conídios (SHAPIRO-ILAN et al, 2002;MOSLIM et al, 2004) …”

Section: Introductionunclassified

Métodos de inoculação e virulência de Beauveria bassiana (Bals.) Vuill. a Cosmopolites sordidus (Germar) (Coleoptera:Curculionidae) em laboratório

et al. 2010

View full text Add to dashboard Cite

ResumoA pesquisa teve o objetivo de avaliar distintos métodos de inoculação de Beauveria bassiana (Bals.) Vuill. em adultos de Cosmopolites sordidus (Germar) em condições de laboratório para utilização em bioensaios de seleção de isolados. Suspensões de conídios do isolado UEL151 foram aplicadas nos insetos através dos seguintes métodos: pulverização, imersão, tópica dorsal e tópica ventral. Em todos os métodos de inoculação obtiveram-se baixos valores de mortalidade total e confirmada, com valor máximo para a imersão dos insetos (21,7%) aos 37 dias após a aplicação (DAA), o qual foi significativamente maior ao resto dos métodos. Verificou-se que a avaliação deve ser de no máximo 22 DAA nas condições deste experimento, já que a taxa de esporulação (mortalidade confirmada/ mortalidade total) diminuiu com o tempo em todos os métodos, com valores de 95,8 e 75,3%, aos 22 e 37 daa, respectivamente no caso da imersão. Os métodos de inoculação tópica dorsal e ventral não causaram virulência significativa de C. sordidus com B. bassiana, pelo que se precisam pesquisar os mesmos, com diferentes concentrações do fungo as usadas neste ensaio. Palavras-chave: Controle biológico, fungo entomopatogênico, bioensaio AbstractThe research aimed to assess different inoculation methods of Beauveria bassiana (Bals.) Vuill. on Cosmopolites sordidus (Germar) adults, in laboratory conditions on an isolates selection bioassay. Conidial suspensions of UEL151 strain were applied on insects through the following methods: spray, immersion, dorsal and ventral topical. Low mortalities were achieved for all inoculation methods, with a higher value for immersion (21.7%) at 37 days after application (DAA), as the rest of methods were significantly lower. The evaluation must be extended to a maximum of 22 DAA because the sporulation rate (confirmed mortality / total mortality) decreased with time in all methods, with values of 95.8 and 75.3%, at 22 and 37 DAA, respectively, on the immersion method. Dorsal and ventral topical methods caused not significant C. sordidus virulence, so new tests are necessary with different fungus concentrations.

show abstract

“…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).…”

mentioning

confidence: 99%

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

Yang

Keyhani

Tang

et al. 2014

Appl Environ Microbiol

Self Cite

View full text Add to dashboard Cite

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.

show abstract

Increased Insect Virulence in Beauveria bassiana Strains Overexpressing an Engineered Chitinase

Cited by 196 publications

References 31 publications

Carboxylate Transporter Gene JEN1 from the Entomopathogenic Fungus Beauveria bassiana Is Involved in Conidiation and Virulence

Carboxylate Transporter Gene JEN1 from the Entomopathogenic Fungus Beauveria bassiana Is Involved in Conidiation and Virulence

Métodos de inoculação e virulência de Beauveria bassiana (Bals.) Vuill. a Cosmopolites sordidus (Germar) (Coleoptera:Curculionidae) em laboratório

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

Contact Info

Product

Resources

About