Linhas gerais In this review, we describe the mechanisms involved in the initiation and development of plant-associated microbial biofilms in general,

Apresentação em tema: "Linhas gerais In this review, we describe the mechanisms involved in the initiation and development of plant-associated microbial biofilms in general,"— Transcrição da apresentação:

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2 Linhas gerais In this review, we describe the mechanisms involved in the initiation and development of plant-associated microbial biofilms in general, with a special emphasis on the root- surface-associated biofilms. Furthermore, examples and references regarding bacterial biofilm formation on aerial plant parts as well as abiotic surfaces are included to enhance the understanding of biofilm formation in general, and to hypothesize and compare and contrast these biofilms to root- associated biofilms.

3 Rizosfera; é a região onde o solo e as raízes das plantas entram em contato. O número de microrganismos na raiz e à sua volta é muito maior do que no solo …critical interface between plant roots and soil where beneficial and harmful interactions between plants and microorganisms occur.

4 Biofilmes nas plantas organized structures called biofilms when colonizing different plant surfaces……with an increasing number of studies on the biochemistry, physiology and genetics of such organized structures (Kearns et al., 2005; Stanley & Lazazzera, 2005), it has become clear that bacterial interactions, growth and formation of biofilms on the root surface involve complex mechanisms Parte do conceito simples e mostra a evolução do conhecimento pela contribuição de outras áreas.( trabalhos recentes de 2005, 2007,

5 Nonpathogenic plant growth promoting rhizobacteria (PGPRs) associated with plant root surfaces are known to contribute towards increases in plant yield by mechanisms such as improved mineral uptake, phytohormone production (Biswas et al., 2000; Ryu et al., 2003, 2004; Fujishige et al., 2006) and competitive suppression of pathogens by production of antibiotics (Mazzola et al., 1992) and induction of secondary metabolite-mediated systemic resistance…Apart fromthe root surface,microbial biofilms are also reported on the phyllosphere and vasculature, especially by pathogenic microorganisms Exemplo: Xylella fastidiosa – uvas frutas cítricas- bloqueia sistema vascular

6 Until 1995, it was generally believed that plants were incapable of being infected by human pathogens. This view changed when Pseudomonas aeruginosa PA14, a human pathogen known to infect burn and cystic fibrosis patients, was recognized as a potent foliar pathogen of a variety of plants, including the model plant Arabidopsis thaliana (Rahme et al., 1995). Additionally, it was determined that many of the same P. aeruginosa virulence factors required for animal pathogenesis are also essential for plant pathogenesis

7 Este ponto de vista mudou quando Pseudomonas aeruginosa PA14, (fibrose cística, foi reconhecido como um potente patógeno foliar de uma variedade de plantas, incluindo a planta modelo Arabidopsis thaliana (Rahme et al., 1995). Além disso, foi determinado que muitos dos mesmos fatores de virulência necessários para patogenia de P. aeruginosa animais também são essenciais para a patogênese da planta

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9 The plant root surface and microbial biofilm associations A schematic hypothetical model of the possible bacterial biofilm formation on the different root regions is depicted in Fig. 1a.

10 Não é bem compreendida: natureza dinâmica Fatores que influênciam associações biofilme- raiz – variações físico-químicas – outros fatores abióticos : disponibilidade de nutrientes, temperatura e umidade relativa – Apesar dos fatores que parecem limitantes há formação das microcolonias e amadurecimento- adaptação – Exudatos radiculares- fábricas (Estima-se que as plantas secretam entre 10% e 44% de seus fotossintatos como exsudatos radiculares)

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