Causes and consequences of plant-associated biofilms

Abstract

The rhizosphere is the critical interface between plant roots and soil where beneficial and harmful interactions between plants and microorganisms occur. Although microorganisms have historically been studied as planktonic (or free-swimming) cells, most are found attached to surfaces, in multicellular assemblies known as biofilms. When found in association with plants, certain bacteria such as plant growth promoting rhizobacteria not only induce plant growth but also protect plants from soil-borne pathogens in a process known as biocontrol. Contrastingly, other rhizobacteria in a biofilm matrix may cause pathogenesis in plants. Although research suggests that biofilm formation on plants is associated with biological control and pathogenic response, little is known about how plants regulate this association. Here, we assess the biological importance of biofilm association on plants.

Microbe-Associated Molecular Patterns-Triggered Root Responses Mediate Beneficial Rhizobacterial Recruitment in Arabidopsis

“…Among these PGPR strains, FB17 rhizoinoculated onto the roots of Arabidopsis plants reduced disease severity, thus inhibiting the proliferation of foliar pathogen Pst DC3000 through induction of JA/ET-mediated ISR and SAmediated SAR (Rudrappa et al, 2010). The magnitude of colonization on the root by beneficial microbes is limited by several factors that include root surface biochemistry and composition of root exudates (Rudrappa et al, 2008a;Doornbos et al, 2011;Chen et al, 2012). It has been speculated that components of root exudates may play a critical role in establishing a beneficial microbiome in the rhizosphere (Lugtenberg et al, 1999;Bais et al, 2006).…”

“…This recent data validates the specificity and preference of B. subtilis for MA. Our previous studies showed that aerial plant pathogenesis involved the induction of MA in root secretions that effectively recruited beneficial rhizobacteria (Rudrappa et al, 2008a(Rudrappa et al, , 2010. We also showed that the pathogenic phyllosphere pathogen, Pst DC3000, induced root ALMT1 expression (Rudrappa et al, 2008b).…”

Fis regulates the competitiveness of Pseudomonas putida on barley roots by inducing biofilm formation

“…One of the important groups of bacteria that are able to colonize the rhizosphere and promote plant growth are the pseudomonads Rudrappa et al, 2008). For instance, Pseudomonas fluorescens, Pseudomonas putida and Pseudomonas chlororaphis have been described as antagonistic towards pathogens of crop plants (Chin-AWoeng et al, 2000;Espinosa-Urgel et al, 2002;Silby et al, 2011).…”

“…Such microcolonies eventually develop into mature biofilms (Ramos-González et al, 2005;Rudrappa et al, 2008;Stanley & Lazazzera, 2004;Villacieros et al, 2003). The formation of biofilms is important, as it protects plants against pathogens.…”

Exploring Quorum Sensing Loci and Biofilm Formation in Bacillus Isolates from Pigeonpea Rhizosphere

“…Bais et al, (2004) observed that lipopeptide production and biocontrol activity are directly related to the ability of B. subtilis to form stable biofilms on plant roots. Surfactin produced early in the growth cycle of the bacterium rapidly increase the surface motility and accelerates the development of multicellular communities called as biofilms (Rudrappa et al, 2008). The involvement of cyclic lipopeptides in biofilm formation by B. subtilis has been reported previously (Branda et al, 2001;Hofemeister et al, 2004).…”