scholarly journals Antibiotic-producing symbionts dynamically transition between plant pathogenicity and insect-defensive mutualism

2017 ◽  
Vol 8 (1) ◽  
Author(s):  
Laura V. Flórez ◽  
Kirstin Scherlach ◽  
Paul Gaube ◽  
Claudia Ross ◽  
Elisabeth Sitte ◽  
...  
Keyword(s):  
Defensive Mutualism ◽  
Plant Pathogenicity

scholarly journals nec1, a Gene Conferring a Necrogenic Phenotype, Is Conserved in Plant-Pathogenic Streptomyces spp. and Linked to a Transposase Pseudogene

1998 ◽  
Vol 11 (10) ◽  
pp. 960-967 ◽  
Author(s):  
Raghida A. Bukhalid ◽  
Soo Young Chung ◽  
Rosemary Loria
Keyword(s):  
Restriction Fragment ◽  
Genetic Basis ◽  
Nucleotide Sequences ◽  
Pathogenic Species ◽  
Potato Tubers ◽  
Biosynthetic Genes ◽  
Oligonucleotide Primers ◽  
Thaxtomin A ◽  
Streptomyces Spp ◽  
Plant Pathogenicity

We are investigating the genetic basis for, and evolution of, plant pathogenicity in Streptomyces spp. The plant-pathogenic species S. scabies, S. acidiscabies, and S. turgidiscabies cause the scab disease of potato and produce the phytotoxins, thaxtomins. Forty-three Streptomyces strains representing the three species were evaluated; all thaxtomin A-producing Streptomyces strains were pathogenic on potato tubers and all but one hybridized to nec1 and ORFtnp, two genes previously cloned from S. scabies ATCC 41973. nec1 confers a pathogenic phenotype on S. lividans TK24, a nonpathogen, and ORFtnp is a transposase pseudogene located 5′ to nec1. The eight nonpathogenic strains tested neither produced thaxtomin A nor hybridized to nec1. ORFtnp and nec1 occurred on a single PvuII restriction fragment in all thaxtomin A-producing Streptomyces strains. The nucleotide sequences of the homologs of nec1 and ORFtnp from two pathogenic strains each of S. scabies, S. acidiscabies, and S. turgidiscabies were identical; oligonucleotide primers specific to this gene amplified homologs from all strains that hybridized to nec1. We propose that nec1 and ORFtnp have been horizontally mobilized from S. scabies to S. acidiscabies and S. turgidiscabies, and that nec1 is involved in pathogenicity and physically linked to the thaxtomin A biosynthetic genes.

scholarly journals Aphid Heritable Symbiont Exploits Defensive Mutualism

2017 ◽  
Vol 83 (8) ◽  
Author(s):  
Matthew R. Doremus ◽  
Kerry M. Oliver
Keyword(s):  
Fungal Pathogens ◽  
Acyrthosiphon Pisum ◽  
Pea Aphid ◽  
Single Infection ◽  
Community Members ◽  
Content Type ◽  
Defensive Mutualism ◽  
Potential Alternative ◽  
Hamiltonella Defensa ◽  
Alternative Routes

ABSTRACT Insects and other animals commonly form symbioses with heritable bacteria, which can exert large influences on host biology and ecology. The pea aphid, Acyrthosiphon pisum, is a model for studying effects of infection with heritable facultative symbionts (HFS), and each of its seven common HFS species has been reported to provide resistance to biotic or abiotic stresses. However, one common HFS, called X-type, rarely occurs as a single infection in field populations and instead typically superinfects individual aphids with Hamiltonella defensa, another HFS that protects aphids against attack by parasitic wasps. Using experimental aphid lines comprised of all possible infection combinations in a uniform aphid genotype, we investigated whether the most common strain of X-type provides any of the established benefits associated with aphid HFS as a single infection or superinfection with H. defensa. We found that X-type does not confer protection to any tested threats, including parasitoid wasps, fungal pathogens, or thermal stress. Instead, component fitness assays identified large costs associated with X-type infection, costs which were ameliorated in superinfected aphids. Together these findings suggest that X-type exploits the aphid/H. defensa mutualism and is maintained primarily as a superinfection by “hitchhiking” via the mutualistic benefits provided by another HFS. Exploitative symbionts potentially restrict the functions and distributions of mutualistic symbioses with effects that extend to other community members. IMPORTANCE Maternally transmitted bacterial symbionts are widespread and can have major impacts on the biology of arthropods, including insects of medical and agricultural importance. Given that host fitness and symbiont fitness are tightly linked, inherited symbionts can spread within host populations by providing beneficial services. Many insects, however, are frequently infected with multiple heritable symbiont species, providing potential alternative routes of symbiont maintenance. Here we show that a common pea aphid symbiont called X-type likely employs an exploitative strategy of hitchhiking off the benefits of a protective symbiont, Hamiltonella. Infection with X-type provides none of the benefits conferred by other aphid symbionts and instead results in large fitness costs, costs lessened by superinfection with Hamiltonella. These findings are corroborated by natural infections in field populations, where X-type is mostly found superinfecting aphids with Hamiltonella. Exploitative symbionts may be common in hosts with communities of heritable symbionts and serve to hasten the breakdown of mutualisms.

Assessment of Plant Pathogenicity of Endophytic Beauveria bassiana in Bt Transgenic and Non-Transgenic Corn

Crop Science ◽  
2001 ◽  
Vol 41 (5) ◽  
pp. 1395-1400 ◽  
Author(s):  
Leslie C. Lewis ◽  
Denny J. Bruck ◽  
Robert D. Gunnarson ◽  
Keith G. Bidne
Keyword(s):  
Beauveria Bassiana ◽  
Transgenic Corn ◽  
Plant Pathogenicity

Evolution of Plant Pathogenicity inFusariumSpecies

2013 ◽  
pp. 485-500 ◽  
Author(s):  
Li-Jun Ma ◽  
H. Corby Kistler ◽  
Martijn Rep
Keyword(s):  
Plant Pathogenicity

Bioinformatic prediction of plant–pathogenicity effector proteins of fungi

2018 ◽  
Vol 46 ◽  
pp. 43-49 ◽  
Author(s):  
Darcy AB Jones ◽  
Stefania Bertazzoni ◽  
Chala J Turo ◽  
Robert A Syme ◽  
James K Hane
Keyword(s):  
Effector Proteins ◽  
Plant Pathogenicity

Fungal endophytes of Festuca rubra increase in frequency following long-term exclusion of rabbits

Botany ◽  
2015 ◽  
Vol 93 (4) ◽  
pp. 233-241 ◽  
Author(s):  
James S. Santangelo ◽  
Nash E. Turley ◽  
Marc T.J. Johnson
Keyword(s):  
Plant Growth ◽  
Intraspecific Competition ◽  
Fungal Endophytes ◽  
Natural Populations ◽  
Fungal Endophyte ◽  
Festuca Rubra ◽  
Red Fescue ◽  
Grass Endophyte ◽  
Defensive Mutualism ◽  
Endophyte Infection

Plant – fungal endophyte interactions are common in nature and they can shape the ecology of plants. Vertically transmitted endophytes are hypothesized to serve as mutualists, protecting plants from herbivores. If this hypothesis is true, then we expect endophytes to be most abundant in the presence of herbivores and least abundant in their absence, assuming endophytes incur a cost to their host. We tested this prediction by studying the effects of intense rabbit (Oryctolagus cuniculus Linnaeus) grazing on grass–endophyte interactions at Silwood Park, UK. We examined seeds of red fescue (Festuca rubra L.) collected from 15 natural populations that were protected from rabbits for 0.3–21 years. Contrary to our prediction, the mean proportion of seeds with endophytes increased 1.84×, from 0.45 to 0.83, following 21 years of rabbit exclusion. To better understand the mechanisms driving this increase in frequency, we conducted a fully factorial greenhouse experiment where we manipulated the presence or absence of endophyte infection, intraspecific competition, and simulated grazing on F. rubra plants. In both damaged and undamaged treatments, infected plants produced approximately twice as much biomass as uninfected plants, and endophytes did not influence tolerance to herbivory. These results suggest that endophytes directly change plant growth but not compensatory responses to damage. In the absence of competitors, infected plants produced 2.17× more biomass than uninfected plants, whereas in the presence of competitors, infected plants produced only 1.55× more biomass than uninfected plants. This difference suggests that intraspecific competition might lessen the benefits of endophyte infection. Our results do not support the defensive mutualism hypothesis, but instead suggest that endophyte-induced plant growth is important in shaping the costs and benefits of endophytes in our system.

scholarly journals Reduction of quinones and phenoxy radicals by extracellular glucose dehydrogenase from Glomerella cingulata suggests a role in plant pathogenicity

Microbiology ◽  
2011 ◽  
Vol 157 (11) ◽  
pp. 3203-3212 ◽  
Author(s):  
Christoph Sygmund ◽  
Miriam Klausberger ◽  
Alfons K. Felice ◽  
Roland Ludwig
Keyword(s):  
Catalytic Properties ◽  
Pathogenic Fungus ◽  
Glucose Dehydrogenase ◽  
Glomerella Cingulata ◽  
Volumetric Activity ◽  
Extracellular Glucose ◽  
Molecular Masses ◽  
Plant Pathogenicity ◽  
Encoding Gene ◽  
Phenoxy Radicals

The plant-pathogenic fungus Glomerella cingulata (anamorph Colletotrichum gloeosporoides) secretes high levels of an FAD-dependent glucose dehydrogenase (GDH) when grown on tomato juice-supplemented media. To elucidate its molecular and catalytic properties, GDH was produced in submerged culture. The highest volumetric activity was obtained in shaking flasks after 6 days of cultivation (3400 U l−1, 4.2 % of total extracellular protein). GDH is a monomeric protein with an isoelectric point of 5.6. The molecular masses of the glycoforms ranged from 95 to 135 kDa, but after deglycosylation, a single 68 kDa band was obtained. The absorption spectrum is typical for an FAD-containing enzyme with maxima at 370 and 458 nm and the cofactor is non-covalently bound. The preferred substrates are glucose and xylose. Suitable electron acceptors are quinones, phenoxy radicals, 2,6-dichloroindophenol, ferricyanide and ferrocenium hexafluorophosphate. In contrast, oxygen turnover is very low. The GDH-encoding gene was cloned and phylogenetic analysis of the translated protein reveals its affiliation to the GMC family of oxidoreductases. The proposed function of this quinone and phenoxy radical reducing enzyme is to neutralize the action of plant laccase, phenoloxidase or peroxidase activities, which are increased in infected plants to evade fungal attack.

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