The root-knot nematode, Meloidogyne incognita, is among the most damaging agricultural pests, particularly to tomato. The mutualistic endophytes Fusarium oxysporum strain Fo162 (Fo162) and Rhizobium ...etli strain G12 (G12) have been shown to systemically induce resistance toward M. incognita. By using triple-split-root tomato plants, spatially separated but simultaneous inoculation of both endophytes did not lead to additive reductions in M. incognita infection. More importantly, spatially separated inoculation of Fo162 and G12 led to a reduction in Fo162 root colonization of 35 and 39% when G12 was inoculated on a separate root section of the same plant in two independent experiments. In an additional split-root experiment, spatial separation of Fo162 and G12 resulted in a reduction of Fo162 root colonization of approximately 50% over the water controls in two independent experiments. The results suggested that the suppressive activity of G12 on Fo162 and M. incognita is possibly related to the induction of specific plant defense mechanisms. Thus, although Fo162 and G12 have the ability to systemically repress M. incognita infection in tomato, they can be considered incompatible biocontrol agents when both organisms are present simultaneously on the same root system.
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► The endophytes Fusarium oxysporum and Rhizobium etli affect Aphis gossypii behavior. ► Spatially-separated co-inoculation of both endophytes reduced the aphid population. ► The ...co-inoculation did not improve the aphid biocontrol respect to single treatment. ► The aphids preferred to feed on endophyte-free than on endophyte-inoculated plants.
The mutualistic root-colonizing endophytes Fusarium oxysporum strain Fo162 (Fo162) and Rhizobium etli strain G12 (G12) have been shown to individually induce systemic resistance against the sucking insect Aphis gossypii Glover (Hom., Aphididae). Simultaneous application of both organisms may be a strategy to further increase the systemic defense responses and thus the biocontrol efficacy. The simultaneous inoculation of both endophytes, either in a mixed or in a spatially-separated way, also reduced the aphid population in comparison to untreated squash plants. However, both types of combined treatments did not lead to significant additive biocontrol levels, i.e. further reduction in the aphid population, when compared to individual inoculation. A choice experiment with intact squash plants showed that the aphids favor feeding on endophyte-free plants, indicating that both Fo162 and G12 are able to affect the host plant preference by the aphids. The data illustrate that cocktail type inoculants comprising of different beneficial microorganisms may not always enhance the biocontrol efficacy against insects. Thus, although both Fo162 and G12 are recognized as biocontrol agents, their mutual interactions and their interactions with the host plant have to be taken into account in co-inoculation strategies in biocontrol.
An organic treatment for control of crown rot disease of banana was developed and evaluated at EARTH University in Costa Rica. Studies were conducted to evaluate the efficacy of Biocto 6 (seed ...extract from citrus) in combination with the wax-based adjuvant Verdiol for control of post-harvest crown rot of banana. The standard commercial fungicide treatment (thiabendazol, imazalil and ammonium sulfate) and an untreated control were included for comparison. Bananas with the various treatments were processed using standard commercial procedures and stored in a refrigerated chamber that was modified to simulate commercial transport, distribution and controlled ripening for exported bananas. Fruit clusters were evaluated for percent weight loss, ripening in storage and crown rot disease severity. At the end of the 28-day storage period, there were no significant differences in percent weight loss between any of the treatments. There was no significant difference in ripening (maturity level) between the organic treatment and the commercial fungicide standard in 2 years of testing. In 2003, the untreated control had a significantly higher maturity rating than the organic or standard fungicide treatment. However, there were no significant differences in any of the treatments in maturity level in 2005. There was no significant difference between the organic and standard fungicide treatment for crown rot control and both treatments had significantly less crown rot than the untreated control. Results indicate that Biocto 6 in combination with Verdiol wax provides a new organic alternative for control of post-harvest crown rot of banana.
Pseudocapacitive charge storage in Ti
C
T
MXenes in acid electrolytes is typically described as involving proton intercalation/deintercalation accompanied by redox switching of the Ti centres and ...protonation/deprotonation of oxygen functional groups. Here we conduct nanoscale electrochemical measurements in a unique experimental configuration, restricting the electrochemical contact area to a small subregion (0.3 µm
) of a monolayer Ti
C
T
flake. In this unique configuration, proton intercalation into interlayer spaces is not possible, and surface processes are isolated from the bulk processes, characteristic of macroscale electrodes. Analysis of the pseudocapacitive response of differently sized MXene flakes indicates that entire MXene flakes are charged through electrochemical contact of only a small basal plane subregion, corresponding to as little as 3% of the flake surface area. Our observation of pseudocapacitive charging outside the electrochemical contact area is suggestive of a fast transport of protons mechanism across the MXene surface.
Culminating in the 1950's, bananas, the world's most extensive perennial monoculture, suffered one of the most devastating disease epidemics in history. In Latin America and the Caribbean, Fusarium ...wilt (FW) caused by the soil-borne fungus Fusarium oxysporum f. sp. cubense (FOC), forced the abandonment of the Gros Michel-based export banana industry. Comparative microbiome analyses performed between healthy and diseased Gros Michel plants on FW-infested farms in Nicaragua and Costa Rica revealed significant shifts in the gammaproteobacterial microbiome. Although we found substantial differences in the banana microbiome between both countries and a higher impact of FOC on farms in Costa Rica than in Nicaragua, the composition especially in the endophytic microhabitats was similar and the general microbiome response to FW followed similar rules. Gammaproteobacterial diversity and community members were identified as potential health indicators. Healthy plants revealed an increase in potentially plant-beneficial Pseudomonas and Stenotrophomonas, while diseased plants showed a preferential occurrence of Enterobacteriaceae known for their plant-degrading capacity. Significantly higher microbial rhizosphere diversity found in healthy plants could be indicative of pathogen suppression events preventing or minimizing disease expression. This first study examining banana microbiome shifts caused by FW under natural field conditions opens new perspectives for its biological control.
MAIN CONCLUSION : The research demonstrated that Arabidopsis can be used as a model system for studying plant–nematode–endophyte tripartite interactions; thus, opening new possibilities for further ...characterizing the molecular mechanisms behind these interactions. Arabidopsis has been established as an important model system for studying plant biology and plant–microbe interactions. We show that this plant can also be used for studying the tripartite interactions among plants, the root-knot nematode Meloidogyne incognita and a beneficial endophytic isolate of Fusarium oxysporum, strain Fo162. In various plant species, Fo162 can systemically reduce M. incognita infection development and fecundity. Here it is shown that Fo162 can also colonize A. thaliana roots without causing disease symptoms, thus behaving as a typical endophyte. As observed for other plants, this endophyte could not migrate from the roots into the shoots and leaves. Direct inoculation of the leaves also did not result in colonization of the plant. A significant increase in plant fresh weight, root length and average root diameter was observed, suggesting the promotion of plant growth by the endophyte. The inoculation of A. thaliana with F. oxysporum strain Fo162 also resulted in a significant reduction in the number of M. incognita juveniles infecting the roots and ultimately the number of galls produced. This was also observed in a split-root experiment, in which the endophyte and nematode were spatially separated. The usefulness of Arabidopsis opens new possibilities for further dissecting complex tripartite interactions at the molecular and biochemical level.
The endophytic fungus
Fusarium oxysporum
strain Fo162 and the endophytic bacterium
Rhizobium etli
strain G12 have been shown to enhance plant resistance toward the root-knot nematode
Meloidogyne ...incognita.
The individual inoculation of tomato seedlings with these antagonists lead to significant reductions in the number of juveniles that penetrated the root and ultimately the number of galls and egg-masses produced. The present study determined the influence of Fo162 and G12 root colonization on juvenile development inside the root system over time after a synchronized nematode infection. The results showed that 14 and 21 days after nematode inoculation, the development into the third-stage juvenile as well as into the adult-stage was significantly lower in endophyte-treated plants when compared to the untreated control, respectively. In addition, Fo162 and G12 treatment led to a significant reduction in the number of eggs per female 35 days after nematode inoculation. The results demonstrated that both Fo162 and G12 not only reduce
M. incognita
root penetration, but also reduce their development and reproduction.
Bananas (Musa spp.) belong to the most important global food commodities, and their cultivation represents the world's largest monoculture. Although the plant-associated microbiome has substantial ...influence on plant growth and health, there is a lack of knowledge of the banana microbiome and its influencing factors. We studied the impact of (i) biogeography, and (ii) agroforestry on the banana-associated gammaproteobacterial microbiome analyzing plants grown in smallholder farms in Nicaragua and Costa Rica. Profiles of 16S rRNA genes revealed high abundances of Pseudomonadales, Enterobacteriales, Xanthomonadales, and Legionellales. An extraordinary high diversity of the gammaproteobacterial microbiota was observed within the endophytic microenvironments (endorhiza and pseudostem), which was similar in both countries. Enterobacteria were identified as dominant group of above-ground plant parts (pseudostem and leaves). Neither biogeography nor agroforestry showed a statistically significant impact on the gammaproteobacterial banana microbiome in general. However, indicator species for each microenvironment and country, as well as for plants grown in Coffea intercropping systems with and without agri-silvicultural production of different Fabaceae trees (Inga spp. in Nicaragua and Erythrina poeppigiana in Costa Rica) could be identified. For example, banana plants grown in agroforestry systems were characterized by an increase of potential plant-beneficial bacteria, like Pseudomonas and Stenotrophomonas, and on the other side by a decrease of Erwinia. Hence, this study could show that as a result of legume-based agroforestry the indigenous banana-associated gammaproteobacterial community noticeably shifted.
Las cepas de Fusarium no patogénicas son importantes para la producción de cultivos, ya que algunos de ellos han mostrado un efecto de inducción de resistencia en las plantas colonizadas, ...predisponiendo el sistema inmune de las plantas a defenderse contra el ataque de plagas y enfermedades. Las bacterias endofíticas son aisladas de los tejidos internos de las plantas, siendo un grupo importante las rhizobacterias. Estudios han demostrado que la inoculación de estas bacterias en diferentes cultivos disminuyó la intensidad de enfermedades causadas por patógenos del suelo, resultando en la promoción de crecimiento y salud de las plantas. Sin embargo, la variabilidad en el nivel de control biológico de las plagas y enfermedades, asociadas a la aplicación simultanea de microorganismos endofíticos, es considerado como un factor limitante al usar agentes antagonistas para la protección de cultivos. En este contexto, la presente investigación evaluó la interacción entre los endofíticos Fusarium oxysporum Fo162 y Rizobium etli G12 al aplicarlos simultáneamente en experimentos in vitro e in vivo. Los resultados indicaron que la bacteria causó una reducción significativa en el crecimiento radial del hongo, así como en su capacidad de colonización radicular. Lo anterior, sugiere que es necesario evaluar la compatibilidad entre microorganismos benéficos, antes de utilizarlos en inoculaciones simultaneas como parte de una estrategia de control biológico.
Access to spiritual support appears to be important in the hospital setting. The offer of spiritual support can be done by different providers such as doctors, nurses or chaplains. Who should ...initiate or coordinate this spiritual care. This study addresses the following questions: 1) How many patients accept spiritual proposition? 2) What is the better mode of proposition? The study's objectives are the assessment and comparison of the rates of acceptance to an offer of spiritual support made by nurses and chaplains. Two hundred twenty-three consecutive hospitalized patients hospitalized received a proposal of spiritual support and were randomly assigned to one of two conditions. Results revealed that 85.8 % of patients accepted the offer in the chaplains' group and 38.5 % in the nurses' group. Acceptance of the offer of spiritual support was positively associated with the proposal being made by the chaplains by the frequency of meditation and age, and negatively related to physical well-being.
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