Bacterial community changes in an industrial algae production system.

While microalgae are a promising feedstock for production of fuels and other chemicals, a challenge for the algal bioproducts industry is obtaining consistent, robust algae growth. Algal cultures include complex bacterial communities and can be difficult to manage because specific bacteria can promote or reduce algae growth. To overcome bacterial contamination, algae growers may use closed photobioreactors designed to reduce the number of contaminant organisms.

Gene amplification confers glyphosate resistance in Amaranthus palmeri.

The herbicide glyphosate became widely used in the United States and other parts of the world after the commercialization of glyphosate-resistant crops. These crops have constitutive overexpression of a glyphosate-insensitive form of the herbicide target site gene, 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS). Increased use of glyphosate over multiple years imposes selective genetic pressure on weed populations.

Host-microbe interactions: shaping the evolution of the plant immune response.

The evolution of the plant immune response has culminated in a highly effective defense system that is able to resist potential attack by microbial pathogens. The primary immune response is referred to as PAMP-triggered immunity (PTI) and has evolved to recognize common features of microbial pathogens. In the coevolution of host-microbe interactions, pathogens acquired the ability to deliver effector proteins to the plant cell to suppress PTI, allowing pathogen growth and disease.

Molecular basis for the RIN4 negative regulation of RPS2 disease resistance.

Recent studies have demonstrated that RPS2, a plasma membrane-localized nucleotide binding site/leucine-rich repeat protein from Arabidopsis thaliana, associates with RPM1 Interacting Protein 4 (RIN4) and that this association functions to modulate the RPS2-mediated defense pathway in response to the bacterial effector protein AvrRpt2. In addition to negatively regulating RPS2 activity, RIN4 is also a target of AvrRpt2, a Cys protease and cognate bacterial effector protein of RPS2. Nicotiana benthamiana has been employed as a heterologous expression system to characterize the RPS2-RIN4 association, defining the domains in RIN4 required for the negative regulation of RPS2 activity.

Molecular characterization of proteolytic cleavage sites of the Pseudomonas syringae effector AvrRpt2.

During infection of Arabidopsis thaliana, the bacterium Pseudomonas syringae pv tomato delivers the effector protein AvrRpt2 into the plant cell cytosol. Within the plant cell, AvrRpt2 undergoes N-terminal processing and causes elimination of Arabidopsis RIN4. Previous work established that AvrRpt2 is a putative cysteine protease, and AvrRpt2 processing and RIN4 elimination require an intact predicted catalytic triad in that AvrRpt2.

Genetic and molecular evidence that the Pseudomonas syringae type III effector protein AvrRpt2 is a cysteine protease.

Upon delivery to the plant cell during infection, the Pseudomonas syringae effector protein AvrRpt2 undergoes proteolytic processing, enhances pathogen virulence and causes the elimination of the Arabidopsis RIN4 protein. A structure-prediction method was employed in order to investigate possible biochemical functions of AvrRpt2. Results of a secondary structure prediction algorithm suggest that the functional C-terminal portion of AvrRpt2 is a cysteine protease.