Increased plant tolerance against chrysanthemum yellows phytoplasma (‘Candidatus Phytoplasma asteris’) following double inoculation with Glomus mosseae BEG12 and Pseudomonas putida S1Pf1Rif

Yang

et al. 2013

J. Basic Microbiol.

Many studies have examined pair‐wise interactions between plants and endophytes, while overlooking the interplays among multiple endosymbionts and their combined impacts on hosts. In this study, Atractylodes lancea plantlets were inoculated with endophytic fungus Acremonium strictum AL16, or endophytic bacterium Acinetobacter sp., or both, to investigate the impacts of the three‐way symbiosis on the host. Our results showed that defense‐related responses of the co‐inoculated plantlets were delayed and weakened relative to plantlets with single inoculants, but no detrimental effects on phyto‐physiology (growth, photosynthesis) were observed after combined inoculations. Quantitative PCR analysis verified a decrease in AL16 colonization density within plants after co‐inoculation with the endobacteria. An in vitro assay was then performed to elucidate the suppressed plant defense responses and reduced fungal colonization by dual inoculation. The data showed that the presence of Acinetobacter sp. reduced AL16 colony diameter and spore germination rate without negatively affecting fungal morphology. Additionally, direct hyphal attachment of the bacterium to AL16 in vitro was visualized by scanning electronic microscopy. Therefore, we propose that a balanced and compatible symbiosis might require constraints conferred by the antagonistic endophyte Acinetobacter sp. on the fungus AL16 in the tripartite endophytic bacterium–fungus–plant system.

Section: Discussionmentioning

confidence: 77%

Consequences of antagonistic interactions between endophytic fungus and bacterium on plant growth and defense responses in Atractylodes lancea

Yang

et al. 2013

J. Basic Microbiol.

“…The present study on the monitoring of the spatiotemporal distribution of these plants with BN symptoms contributes to the further understanding of how complex the population structure of stolbur phytoplasma is, whilst also raising questions about the different abilities of the different vectors to acquire these vmp1 genotypes, particularly in light of recent BN epidemiological studies (Johannesen et al ., ). These data can also contribute to better management of phytoplasma disease, together with weed control and increased plant resistance (D'Amelio et al ., ; Maixner, ; Romanazzi et al ., ), thus also further promoting sustainable agricultural practices.…”

Section: Discussionmentioning

confidence: 99%

Spatial and temporal stolbur population structure in a cv. Chardonnay vineyard according to vmp1 gene characterization

2013

Bois noir is a grapevine disease caused by the stolbur phytoplasma. It is widespread in all European and Mediterranean viticultural areas, and it can induce severe damage to the quality and quantity of production. The recent disease recrudescence has encouraged studies on the use of molecular markers to assess the genetic diversity of stolbur strains. The aim of this study was to evaluate the presence of Bois noir symptoms and to monitor the spatial genetic structure of the stolbur population according to vmp1 genotypes, through 2011 and 2012 in a cv. Chardonnay vineyard. In both years, there were increased vines with symptoms from July to September. The analysis of dispersal indices showed that the spatial distribution was uniform in the vineyard. However, the two-dimensional contour maps show that Bois noir severity was higher in plants located on the borders than in the central parts of the vineyard. Stolbur population was composed of two prevalent vmp genotypes (V14, V12) across both years, along with other minor haplotypes (V3, V4, V9, V11, V15, V18, in 2011; V3, V18 in 2012). The data indicate that the vmp1 gene is an efficient marker to study the population structure of stolbur phytoplasma, to track the movement of the pathogen, and to identify the inoculum source, which will all serve in the planning of control strategies.

“…CY viability decreased over time only in the control plants. This result suggests that, irrespective of the presence of the AM fungus, CY infected plants loose the capability to fully support phytoplasma metabolic activity with time (D'Amelio et al 2011). This hypothesis is consistent with the alteration of photosyntate transport efficiency in phloematic vessel, due to callose deposition on the sieve elements, observed through electron microscopy in CY plants.…”

Section: Discussionmentioning

confidence: 73%

Effects of two AM fungi on phytoplasma infection in the model plant Chrysanthemum carinatum

Sampò

D’Agostino

Bosco

et al. 2012

AFSci

Phytoplasmas are plant pathogenic bacteria, naturally transmitted by insects and confined in the phloem of the host plant, where they take up nutrients and eventually cause plant death. Their control is mainly based on insecticide treatments. The aim of this work was to study the effect of two AM fungi in modifying plant response to chrysanthemum yellows phytoplasma (CY) infection in chrysanthemum plants. Inoculation of Glomus intraradices BB-E and G. mosseae BEG12 reduced the damage caused by this plant pathogen in the aerial part of the plant, increased plant tolerance to the infection and reduced the severity of symptom expression, probably in a systemic way. Inoculation with G. mosseae did not alter CY multiplication and viability in young leaves, whilst the morphology of CY mature leaves was typical of senescent cells. Possible mechanisms involved are discussed.