Recognition and response to prospective competitors are crucial variables that must be considered in resource distribution and utilization in plant communities. Associated behaviors are largely mediated through the exchange of low-molecular weight exudates. These cues can significantly alter the root system architecture (RSA) between neighboring plants and are routinely sensitive enough to distinguish between plants of the same or different accessions, a phenomenon known as kin recognition (KR). Such refined discrimination of identity, based on the composition and detection of patterns of exudate signals is remarkable and provides insight into the chemical ecology of plant-plant interactions. The discovery that KR occurs in Arabidopsis thaliana provides a model system to resolve many of the mechanistic questions associated with this process. We hypothesized that the low-molecular weight cues which direct changes to the RSA during KR was driven by nutrient availability. Here we present evidence in support of a nutrient-inducible model for KR. Our findings underscore how exudate production and detection are influenced by nutrient availability as well as how this information is integrated into 'decisions' about competition and root system architecture which may have broader impacts on community composition.

Significance and Impact of the Study: The Casearia plant extracts exhibited important antifungal activity on wood decay fungi and triggered oxidative stress process, an inhibitory mechanism rarely studied in filamentous fungi exposed to plant extracts. Therefore, a starting point was provided for the development of natural compounds-based products as an alternative to chemical fungicides. In addition, subsidies were given to further studies in order to elucidate in more detail how compounds present in extracts of native tropical plants affect the physiology of fungi. AbstractLigninolytic fungi take part in critical processes in ecosystems such as nutrient recycling; however, some fungal species can be pathogenic to forest and urban trees and deteriorate wood products. The tropical flora is an important source of antimicrobial compounds environmentally safer than traditional wood preservatives. Therefore, this study aimed to evaluate the inhibitory activity of ethanol plant extracts of Casearia sylvestris and Casearia decandra on the white-rot wood decay basidiomycetes Trametes villosa and Pycnoporus sanguineus. In addition, the effect of the extracts on the fungal antioxidative metabolism was studied. Among the different substances present in the extracts, the phytochemical analyses identified a clerodane diterpenoid (C. sylvestris) and cinnamic acid, hydroquinone and b-sitosterol (C. decandra). The extracts inhibited the fungi up to 70% and caused hyphal morphology changes. The extracts triggered oxidative stress process as indicated by the increased levels of the antioxidant enzymes catalase and glutathione reductase. Therefore, the Casearia extracts are a potential source of natural biocides to control wood decay fungi, and one of the mechanisms of action is the oxidative stress.

-(Leaf extracts of Casearia sylvestris and Casearia decandra affect growth and production of ligninolytic enzymes in wood decay basidiomycetes). White-rot basidiomycetes are able to deteriorate wood products and be pathogenic to living trees, requiring, thus requiring control. The tropical flora is an important source of eco-friendly antifungal compounds; however, the knowledge on how leaf extracts affect the fungal physiology is limited. Therefore, in the present work we investigated the influence of ethanolic leaf extracts of Casearia sylvestris and C. decandra at 0.1 mg mL -1 on the production of ligninolytic enzymes by Trametes villosa, Ganoderma australe and Pycnoporus sanguineus. Overall, the extracts inhibited the mycelial growth and the production of biomass. Additionally, C. sylvestris extract reduced the production of manganese peroxidase and laccase; however, the exposure to C. decandra extract resulted in variable responses. Therefore, enzymes related to lignin degradation are potential targets to control wood decay fungi by plant bioactive compounds, as their ability to colonize the substrate may be impaired. Keywords: antimicrobial, biodeterioration, lignin, phytopathogen, white rot RESUMO -(Extratos foliares de Casearia sylvestris e Casearia decandra afetam crescimento e produção de enzimas ligninolíticas em basidiomicetos deterioradores de madeira). Basidiomicetos de podridão branca são capazes de deteriorar madeira e atuar como patógenos de árvores. A flora tropical é uma importante fonte de compostos antifúngicos ecologicamente seguros, entretanto, o conhecimento de como extratos vegetais afetam a fisiologia fúngica é limitado. Portanto, neste trabalho foi investigada a influência de extratos etanólicos de folhas de Casearia sylvestris e C. decandra, na concentração de 0,1 mg mL -1 , sobre a produção de enzimas ligninolíticas por Trametes villosa, Ganoderma australe e Pycnoporus sanguineus. De modo geral, os extratos inibiram o crescimento micelial e a produção de biomassa. Além disso, o extrato de C. sylvestris reduziu a produção de manganês peroxidase e lacase, porém as respostas ao extrato de C. decandra foram variáveis. Deste modo, enzimas envolvidas na degradação da lignina são alvos potenciais para o controle de fungos causadores de podridão em madeira por compostos vegetais bioativos, uma vez que a capacidade desses microrganismos para colonizar o substrato pode ser prejudicada.

Many organisms have evolved to identify and respond to differences in genetic relatedness between conspecifics, allowing them to select between competitive and facilitative strategies to improve fitness. Due to their sessile nature, plants frequently draw from the same pool of nutrients, and the ability to limit competition between closely related conspecifics would be advantageous. Studies with Arabidopsis thaliana have confirmed that plants can detect variations at the accession level and alter their root system architecture (RSA) in response, presumably for regulating nutrient uptake. The phenotypic impact of this accession-recognition on the RSA is influenced by nutrient availability, underscoring the importance of plant-plant recognition in their growth and fitness. Thus far, these observations have been limited to short-term studies (<21 days) of only the RSA of this model angiosperm. Here we exploit nutrient-mediated regulation of accession-recognition to observe how this plant-plant recognition phenomenon influences growth from germination to flowering in A. thaliana . Our work identifies root and shoot traits that are affected by nutrient-mediated accession recognition. By coupling phenotypic assays to mass spectrometry-based studies of primary metabolite distribution, we provide preliminary insight into the biochemical underpinnings of the changes observed during these plant-plant responses. Most notably that late-stage changes in sucrose metabolism in members of the same accession drove early flowering. This work underscores the need to evaluate accession-recognition under the context of nutrient availability and consider responses throughout the plant’s life, not simply at the earliest stages of interaction.