Exploring interactions of plant microbiomes

A plethora of microbial cells is present in every gram of soil, and microbes are found extensively in plant and animal tissues. The mechanisms governed by microorganisms in the regulation of physiological processes of their hosts have been extensively studied in the light of recent findings on microbiomes. In plants, the components of these microbiomes may form distinct communities, such as those inhabiting the plant rhizosphere, the endosphere and the phyllosphere. In each of these niches, the "microbial tissue" is established by, and responds to, specific selective pressures. Although there is no clear picture of the overall role of the plant microbiome, there is substantial evidence that these communities are involved in disease control, enhance nutrient acquisition, and affect stress tolerance. In this review, we first summarize features of microbial communities that compose the plant microbiome and further present a series of studies describing the underpinning factors that shape the phylogenetic and functional plant-associated communities. We advocate the idea that understanding the mechanisms by which plants select and interact with their microbiomes may have a direct effect on plant development and health, and further lead to the establishment of novel microbiome-driven strategies, that can cope with the development of a more sustainable agriculture

Mycoparasitic nature of Bionectria sp. strain 6.21

In this study, a Bionectria sp. strain isolated from citrus rhizosphere was evaluated for its potential in inhibiting the growth of Rhizoctonia solani and Pythium aphanidermatum. It was demonstrated that Bionectria sp. 6.21 inhibited the growth of P. aphanidermatum and R. solani. In dual cultures, however, the antagonist only parasitised R. solani. Regarding the assay involving P. aphanidermatum, a lack of mycoparasitic ability was demonstrated. Crude extract of Bionectria completely inhibited the mycelial growth of both fungi. It appears that the main mechanism involved in the antagonism of Pythium by Bionectria is through antibiotic production. The antagonistic fungus released extracellular secondary metabolites. The metabolites were found to be inhibitory to both plant pathogenic fungi. From the crude extract, eleven fractions were obtained and tested for their antifungal properties. Two of them showed very strong activity against P. aphanidermatum. The obtained results indicated that this biocontrol agent has both antibiotic and mycoparasitic properties. On the other hand, evidence obtained from Scanning Electron Microscopy (SEM) suggests the involvement of an enzymatic process, with enzymatic digestion playing a major role in the parasitism of Bionectria sp. 6.21. In conclusion, these results provide evidence that mainly due to mycoparasitism, this strain has the potential to become a good candidate for biological control

Antitumoral, Antioxidant And Antimicrobial Molecules From Combretum Rupicola

This investigation describes the anticancer, antioxidant and antimicrobial properties of the extracts of Combretum rupicola, a native plant from Northeast of Brazil. Methanolic, ethyl acetate and chloroform extracts from leaves of C. rupicola were evaluated in relation to their potential in inhibiting the cell growth and cytotoxic properties against nine human cancer cell lines (MCF-7, NCI-ADR/RES, OVCAR-3, PC-3, HT-29, NCIH460, 786-O, UACC-62, K-562). In addition, antioxidant activity of these extracts was measured using DPPH as radical scavenging assay and the antimicrobial activities against nine pathogens were tested by agar diffusion method. Preliminary results showed that the this plant demonstrates to have moderate activity against bacteria but, on the other side, the extracts showed significant anticancer activitiesagainst four cell lines and the most significant activity was observed against MCF-7 (65.9 μg mL-1), highest inhibitory concentration IC50 0.22 μg mL-1 for antioxidant activity. 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