MV, FH, MJV and LR provided the bacteria culture collection for t

MV, FH, MJV and LR provided the bacteria culture collection for the study and helped to draft the manuscript. NFA and NC conceived of the study and participated in its design and coordination and helped to draft the manuscript. All authors read and approved the final manuscript.”
“Background During their life cycles, phytopathogenic bacteria possess an epiphyte growth stage during which they can grow

and reproduce on the surface of a plant without causing disease. However, when conditions are favorable, the bacteria enter a pathogenic stage that leads to disease development. It is known that a complex interaction between key factors must exist for the development of the disease in plants, represented as “disease triangle”. This involves the interaction of a susceptible MGCD0103 host, a virulent pathogen, and environmental conditions favorable for disease development [1, 2]. Regarding environmental conditions, temperature is a key factor in most plant diseases, which are favored mainly by low temperatures [1, 3, 4]. The influence of low temperature on disease development is predominantly due to the expression of various pathogenicity

and/or virulence factors by the pathogens, which influences plant health. Several bacterial phytopathogens, such as Pseudomonas syringae and Erwinia sp., produce disease in their host plants in response to low temperature, which appears to P005091 mouse be the cue for these phytoBatimastat mouse pathogens to produce virulence factors, including toxins, cell-wall degrading enzymes, and effector proteins [4]. Thus, low temperatures are an important environmental parameter in the development of most diseases in plants. One of the most common and economically important diseases is the bean disease (Phaseolus vulgaris L.) known as “halo blight” because it causes major field crop losses. This disease, caused by the bacterial pathogen P. syringae pv. phaseolicola, affects both the leaves and pods [5–7]. Cool temperatures (less than 25°C) favor disease development, a condition that also favors production of the major virulence factor of the pathogen, known as phaseolotoxin [8, 9]. Phaseolotoxin is a non-host specific and chlorosis-inducing toxin

that acts as a reversible inhibitor of the enzyme ornithine carbamoyltransferase (OCTase; EC2.1.3.3), which catalyzes the conversion of ornithine to citruline in the Astemizole arginine biosynthetic pathway [10, 11]. The production of phaseolotoxin by P. syringae pv. phaseolicola is regulated mainly by temperature and is optimally produced at 18°C-20°C, whereas at 28°C (the optimal growth temperature for this bacterium), the toxin is not detected [8, 9]. Genes whose products are involved in phaseolotoxin synthesis are clustered within of a chromosomal region known as the “Pht cluster”, whose expression is also low temperature (18°C) dependent [12]. Thus, like other phytopathogenic bacteria, low temperatures play an important role in P. syringae pv. phaseolicola for the development of halo blight disease.

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