Differential expression of insect and plant specific adhesin genes, Mad1 and Mad2, in Metarhizium robertsii

Barelli, Larissa; Padilla-Guerrero, Israel Enrique; Bidochka, Michael

doi:10.1016/j.funbio.2011.08.003

Cited by 24 publications

(20 citation statements)

References 56 publications

(46 reference statements)

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“…Similarly, the post diauxic shift (PDS) element mediates transcriptional activation in response to nutritional limitation [24], [25]. The presence of these transcriptional elements is consistent with the finding that Mad2 is upregulated under nutrient deprivation [21].…”

Section: Discussionsupporting

confidence: 76%

“…Future research could focus on the expression of Mad2 between species since there was variation present within the promoter region. Several putative transcriptional elements have been identified within the Mad2 promoter [21], however, the analyses presented here focused on the variable STRE, PDS, degenerative TATA box, and TATA box-like regions. The stress response element (STRE) activates genes under various stress conditions, including glucose starvation [22], [23].…”

Section: Discussionmentioning

confidence: 99%

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Variability in the Insect and Plant Adhesins, Mad1 and Mad2, within the Fungal Genus Metarhizium Suggest Plant Adaptation as an Evolutionary Force

Wyrebek

Bidochka

2013

PLoS ONE

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Several species of the insect pathogenic fungus Metarhizium are associated with certain plant types and genome analyses suggested a bifunctional lifestyle; as an insect pathogen and as a plant symbiont. Here we wanted to explore whether there was more variation in genes devoted to plant association (Mad2) or to insect association (Mad1) overall in the genus Metarhizium. Greater divergence within the genus Metarhizium in one of these genes may provide evidence for whether host insect or plant is a driving force in adaptation and evolution in the genus Metarhizium. We compared differences in variation in the insect adhesin gene, Mad1, which enables attachment to insect cuticle, and the plant adhesin gene, Mad2, which enables attachment to plants. Overall variation for the Mad1 promoter region (7.1%), Mad1 open reading frame (6.7%), and Mad2 open reading frame (7.4%) were similar, while it was higher in the Mad2 promoter region (9.9%). Analysis of the transcriptional elements within the Mad2 promoter region revealed variable STRE, PDS, degenerative TATA box, and TATA box-like regions, while this level of variation was not found for Mad1. Sequences were also phylogenetically compared to EF-1α, which is used for species identification, in 14 isolates representing 7 different species in the genus Metarhizium. Phylogenetic analysis demonstrated that the Mad2 phylogeny is more congruent with 5′ EF-1α than Mad1. This would suggest that Mad2 has diverged among Metarhizium lineages, contributing to clade- and species-specific variation, while it appears that Mad1 has been largely conserved. While other abiotic and biotic factors cannot be excluded in contributing to divergence, these results suggest that plant relationships, rather than insect host, have been a major driving factor in the divergence of the genus Metarhizium.

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Section: Discussionsupporting

confidence: 76%

Section: Discussionmentioning

confidence: 99%

Variability in the Insect and Plant Adhesins, Mad1 and Mad2, within the Fungal Genus Metarhizium Suggest Plant Adaptation as an Evolutionary Force

Wyrebek

Bidochka

2013

PLoS ONE

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“…Equally important are the adhesins, Mad1 and Mad2 , which play an important role in adhesion of M. anisopliae to the insect cuticle [9]. Disruption of the Mad1 gene reduces virulence by reducing adhesion of conidia to the host surface [10]. It is assumed that the pattern of infection outlined above occurs in aquatic mosquito larvae [2].This paper demonstrates for the first time that M. anisopliae kills the mosquito larvae via a mechanism which does not entail the traditional infection processes.…”

Section: Introductionmentioning

confidence: 88%

Metarhizium anisopliae Pathogenesis of Mosquito Larvae: A Verdict of Accidental Death

et al. 2013

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Metarhizium anisopliae, a fungal pathogen of terrestrial arthropods, kills the aquatic larvae of Aedes aegypti, the vector of dengue and yellow fever. The fungus kills without adhering to the host cuticle. Ingested conidia also fail to germinate and are expelled in fecal pellets. This study investigates the mechanism by which this fungus adapted to terrestrial hosts kills aquatic mosquito larvae. Genes associated with the M. anisopliae early pathogenic response (proteinases Pr1 and Pr2, and adhesins, Mad1 and Mad2) are upregulated in the presence of larvae, but the established infection process observed in terrestrial hosts does not progress and insecticidal destruxins were not detected. Protease inhibitors reduce larval mortality indicating the importance of proteases in the host interaction. The Ae. aegypti immune response to M. anisopliae appears limited, whilst the oxidative stress response gene encoding for thiol peroxidase is upregulated. Cecropin and Hsp70 genes are downregulated as larval death occurs, and insect mortality appears to be linked to autolysis through caspase activity regulated by Hsp70 and inhibited, in infected larvae, by protease inhibitors. Evidence is presented that a traditional host-pathogen response does not occur as the species have not evolved to interact. M. anisopliae retains pre-formed pathogenic determinants which mediate host mortality, but unlike true aquatic fungal pathogens, does not recognise and colonise the larval host.

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“…Mucilage is often secreted to consolidate the attachment of the fungus to the host surface. The adhesins, Mad1 and Mad2 , assist in attachment of the fungus to insect and plant surfaces, as a result Mad1 also contributes to pathogenesis [ 17 , 26 ].…”

Section: Introductionmentioning

confidence: 99%

Conidia of the insect pathogenic fungus, Metarhizium anisopliae , fail to adhere to mosquito larval cuticle

et al. 2014

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Adhesion of conidia of the insect pathogenic fungus, Metarhizium anisopliae, to the arthropod host cuticle initially involves hydrophobic forces followed by consolidation facilitated by the action of extracellular enzymes and secretion of mucilage. Gene expression analysis and atomic force microscopy were used to directly quantify recognition and adhesion between single conidia of M. anisopliae and the cuticle of the aquatic larval stage of Aedes aegypti and a representative terrestrial host, Tenebrio molitor. Gene expression data indicated recognition by the pathogen of both hosts; however, the forces for adhesion to the mosquito were approximately five times lower than those observed for Tenebrio. Although weak forces were recorded in response to Aedes, Metarhizium was unable to consolidate firm attachment. An analysis of the cuticular composition revealed an absence of long-chain hydrocarbons in Aedes larvae which are thought to be required for fungal development on host cuticle. This study provides, to our knowledge, the first evidence that Metarhizium does not form firm attachment to Ae. aegypti larvae in situ, therefore preventing the normal route of invasion and pathogenesis from occuring.

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Differential expression of insect and plant specific adhesin genes, Mad1 and Mad2, in Metarhizium robertsii

Cited by 24 publications

References 56 publications

Variability in the Insect and Plant Adhesins, Mad1 and Mad2, within the Fungal Genus Metarhizium Suggest Plant Adaptation as an Evolutionary Force

Variability in the Insect and Plant Adhesins, Mad1 and Mad2, within the Fungal Genus Metarhizium Suggest Plant Adaptation as an Evolutionary Force

Metarhizium anisopliae Pathogenesis of Mosquito Larvae: A Verdict of Accidental Death

Conidia of the insect pathogenic fungus, Metarhizium anisopliae , fail to adhere to mosquito larval cuticle

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