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- Temporal dynamics of endophytic microbial communities colonizing olives infested and non-infested by olive fruit flyPublication . Lopes, Teresa; Baptista, Paula; Ramos, Vítor Manuel CapelaOlive fruit fly, Bactrocera oleae (Rossi) (Diptera: Tephritidae) is the major insect pest of olive crop worldwide. Distinct olive cultivars exhibit different susceptibility to olive fruit fly infestation and the causes of this phenomenon are still unclear. Here, we wanted to disclose the role of biotic and abiotic factors in shaping the olive-associated endophytes and their implication in conferring different host susceptibilities to olive fly. The importance of air as a source of endophytes was additionally evaluated. Accordingly, the endophytic microbial composition of infested and non-infested fruits from cultivars Madural (susceptible to olive fly) and Cobrançosa (less susceptible) were studied over two maturation indexes in two olive orchards under organic and integrated management. Endophytic diversity assessed by rRNA sequencing of cultivable isolates revealed a larger consortium of bacteria associated to olives than fungi. The bacterial communities were predominantly composed of Proteobacteria and Actinobacteria while the fungal community was dominated by members belonging to Ascomycota. The overall assemblages of endophytes in fruits were shaped mainly by the maturation index, followed by the type of management and cultivar, being the level of infestation a negligible effect. Despite this, it was found a clear positive association of a set of endophytes with the resistant cultivar (Pseudomonas citronellolis, Rhodococcus fascians, Actinobacterium sp., Cladosporium sp. 2, Stereum sp. and Aspergillus flavus), organic orchard and non-infested fruits (Microbacterium paraoxydans, Kocuria sp., Penicillium solitum, Cladosporium sp3. and Vishniacozyma victoriae). The microbial composition of the air and the fruit endosphere were completely different, suggesting that there are other sources of endophytes. Our study provides potential microbial candidates to further evaluate their role on host cultivar susceptibility/resistance to fruit fly.
- Exploring macrophytes’ microbial populations dynamics to enhance bioremediation in constructed wetlands for industrial pollutants removal in sustainable wastewater treatmentPublication . Ijoma, Grace N.; Lopes, Teresa; Mannie, Thulani; Mhlongo, Thandazile N.Toxic contaminants from intense industrial operations are entering wetlands, harming human health and biodiversity. Macrophytes serve as principal producers in aquatic environments including natural wetlands, providing shelter, food, and, most crucially, intricate relationships with the surrounding microbial assemblage for support and microorganisms attachment. Wetlands have been nature's kidneys, for filtering water. Recent research has examined macrophytes' phytoremediation abilities. With recent improvements focused on engineered wetland technology, microbiological characterization, and genetic engineering, phytoremediation strategies have also benefited. However, little research has examined the role surrounding microbial population play on macrophyte efficiency in pollutant degradation, the extent and even mechanisms of these interactions, and their potential utility in wastewater treatment of diverse industrial effluents. Our bid for greener solutions implies that macrophyte-microorganisms’ interspecific interactions for in situ treatment of effluents should be optimised to remove contaminants before discharge in natural waterbodies or for recycle water usage. This review provides for the varied types of plants and microbial interspecific interactions beneficial to effective phytoremediation processes in artificial wetland design as well as considerations and modifications in constructed wetland designs necessary to improve the bioremediation processes. Additionally, the review discusses the latest advancements in genetic engineering techniques that can enhance the effectiveness of phyto-assisted wastewater treatment. We will also explore the potential utilisation of invasive species for their demonstrated ability to remove pollutants in the controlled setting of constructed wetlands.
- Potential of the endophyte Penicillium commune in the control of olive anthracnose via induction of antifungal volatiles in host plantPublication . Silva, Sofia; Costa, Helgeneusa Neto da; Lopes, Teresa; Ramos, Vitor; Rodrigues, Nuno; Pereira, J.A.; Lino-Neto, Teresa; Baptista, PaulaOlive anthracnose, caused by several Colletotrichum species, is the most economically harmful fruit disease of the olive crop. This work aimed to evaluate the ability of the endophyte Penicillium commune CIMO 14FM009 to protect the olive tree against Colletotrichum nymphaeae via induction of plant volatile organic compounds (VOCs). Accordingly, olive tree branches were inoculated with the endophyte and one month later with the pathogen. After 0, 3, and 24 h of pathogen inoculation, the volatile composition of leaves and fruits was analyzed by HSSPME- GC/MS, and compared with controls (branches inoculated with buffer, endophyte, or pathogen). The effect of plant-derived volatiles on C. nymphaeae was also evaluated. Penicillium commune induced the release of VOCs on the olive trees, with the capacity to reduce significantly the growth (up to 1.4-fold) and sporulation (up to 1.2-fold) of C. nymphaeae. This effect was most notorious on olives than on leaves, and occurred 3 h after pathogen-challenge, suggesting the need for a stressful stimulus for the production of antifungal VOCs. The observed inhibition was associated to a specific set of VOCs released from olives (mostly belonging to the alcohols and esters chemical classes) and leaves (mostly belonging to the alkenes). Curiously, a set of VOCs belonging to alkene, alkane and ester classes, were emitted exclusively in olive branches inoculated with C. nymphaeae. These findings provide new possibilities for controlling olive anthracnose using P. commune and/or volatiles, which efficacy should be tested in future works.
- Biocontrol ability and production of volatile organic compounds as a potential mechanism of action of olive endophytes against Colletotrichum acutatumPublication . Sdiri, Yosra; Lopes, Teresa; Rodrigues, Nuno; Silva, Kevin; Rodrigues, Isabel; Pereira, J.A.; Baptista, PaulaOlive anthracnose, mainly caused by Colletotrichum acutatum, is considered a key biotic constraint of the olive crop worldwide. This work aimed to evaluate the ability of the endophytes Aureobasidium pullulans and Sarocladium summerbellii isolated from olive trees to reduce C. acutatum growth and anthracnose symptoms, and to assess A. pullulans-mediated changes in olive fruit volatile organic compounds (VOCs) and their consequences on anthracnose development. Among the endophytes tested, only A. pullulans significantly reduced the incidence (up to 10-fold) and severity (up to 35-fold) of anthracnose in detached fruits, as well as the growth (up to 1.3-fold), sporulation (up to 5.9-fold) and germination (up to 3.5-fold) of C. acutatum in dual culture assays. Gas chromatography–mass spectrometry analysis of olives inoculated with A. pullulans + C. acutatum and controls (olives inoculated with C. acutatum, A. pullulans or Tween) led to the identification of 37 VOCs, with alcohols being the most diversified and abundant class. The volatile profile of A. pullulans + C. acutatum revealed qualitative and quantitative differences from the controls and varied over the time course of microbial interactions. The most significant differences among treatments were observed at a maximal reduction in anthracnose development. At this stage, a set of VOCs, particularly Z-3-hexen-1-ol, benzyl alcohol and nonanal, were highly positively correlated with the A. pullulans + C. acutatum treatment, suggesting they play a critical role in anthracnose reduction. 6-Methyl-5-hepten-2-one and 2-nonanone were positively associated with the C. acutatum treatment and thus likely have a role in pathogen infection.