Burkholderia glumae: next major pathogen of rice?

Abstract

Bacteria exhibit an optimal growth rate in culture media with sufficient nutrients at an optimal temperature and pH. In addition, the concentration of solutes plays a critical role in bacterial growth and survival. Glutamate is known to be a major anionic solute involved in osmoregu-lation and the bacterial cell's response to changes in solute concentration. To determine how glutamate uptake is involved in osmoregulation in the rice bacterial pathogen Burkhol-deria glumae BGR1, we mutated the gltI gene encoding a periplasmic substrate binding protein of a glutamate transport system to abolish glutamate uptake, and monitored the growth of the gltI null mutant in Luria-Bertani medium. We found that the gltI null mutant showed a slower growth rate than the wild-type strain and experienced hyperosmotic stress resulting in water loss from the cytoplasm in stationary phase. When the incubation time was extended , the mutant population collapsed due to the hyperosmotic stress. The gltI null mutant exhibited loss of adaptability under both hypoosmotic and hyperosmotic stresses. The growth rate of the gltI null mutant was restored to the level of wild-type growth by exogenous addition of glycine betaine to the culture medium, indicating that glycine betaine is a compatible solute in B. glumae. These results indicate that glutamate uptake from the environment plays a key role in osmoregulation in B. glumae.

The awr Gene Family Encodes a Novel Class of Ralstonia solanacearum Type III Effectors Displaying Virulence and Avirulence Activities

“…The well-known instability of the R. solanacearum genome (Guidot et al 2009) and the fact that Burkholderia spp. and A. avenae share the same soil habitat (Attree and Attree, 2001;Ham et al 2010;Viallard et al 1998;Willems et al 1992) render these gene transfers very likely. The evolutionary model results in five AWR members in each Ralstonia strain, except in UW551 and Molk5, where an extra duplication event in awr5 gave rise to awr6.…”

“…AWR are also present in other plant-pathogenic strains with emerging importance such as the rice pathogen B. glumae, other Burkholderia strains, Acidovorax avenae infecting cucurbitaceae or poaceae and some Xanthomonas pathovars causing disease in rice, pepper, tomato, brasicaceae, citrus, or even a bacterial wilt in banana (Ham et al 2010;Mole et al 2007;Smith et al 2008;Viallard et al 1998;Willems et al 1992). The long evolution suffered by this ancestral family and the disparate contexts in which it functions may have facilitated the functional diversification that we have observed for its members.…”

EliA is required for inducing the stearyl alcohol-mediated expression of secretory proteins and production of polyester in Ralstonia sp. NT80

“…The secretory lipase has also been shown to be a virulence factor of Xanthomonas oryzae pv. oryzae and B. glumae, which are pathogenic to rice plants (Aparna et al, 2009;Ham et al, 2011). While the function of Ndk in the virulence of phytopathogenic bacteria remains unclear, it is known that secretory Ndk is involved in the virulence of Pseudomonas aeruginosa and M. tuberculosis, which are pathogenic to humans (Chakrabarty, 1998;Kim et al, 2014).…”

Burkholderia glumae en el cultivo de arroz en Costa Rica.

“…Se reportan varios factores de virulencia en B. glumae, entre ellos, la catalasa, la biogénesis flagelar, un sistema de secreción tipo III y una fitotoxina llamada toxoflavina (Ham et al, 2011); sin embargo, el principal mediador de daño es la toxoflavina, una toxina con propiedades físicas y químicas similares a la riboflavina y que se evidencia en las cepas productoras de la toxina por la pigmentación amarilla que produce en los medios de cultivo (Nandakumar et al, 2009).…”