Pathogenicity of two Pratylenchus coffeae populations from Brazil on coffee plants

There is limited information on the influence of Pratylenchus coffeae on the growth and development of coffee plants, in spite of the widespread occurrence of this nematode in coffee plantations. In addition, populations of P. coffeae vary in morphological and molecular features, as well as reproductive fitness and pathological potential. The objective of the present study was to compare the pathogenicity of two Brazilian P. coffeae populations, K-5 from Coffea arabica roots and M-2 from Aglaonema sp. roots, in terms of their influence on the plant growth and photosynthesis of Arabian coffee (C. arabica). Five experiments were conducted in controlled conditions, and the results demonstrated that K-5 is pathogenic on coffee, as it can reproduce and causes obvious damage on the plant. Moreover K-5 proved to be very virulent on Arabian coffee, considering its effects on seedling mortality, plant growth and photosynthesis. By contrast, M-2 was considered to be of low virulence, or even non-pathogenic, on coffee because it failed to reproduce. Thus, the results indicate that K-5 and M-2 may be distinct species, supporting the hypothesis of previous authors.9685385

Deletion of BmoR affects the expression of genes related to thiol/disulfide balance in Bacteroides fragilis

Bacteroides fragilis, an opportunistic pathogen and commensal bacterium in the gut, is one the most aerotolerant species among strict anaerobes. However, the mechanisms that control gene regulation in response to oxidative stress are not completely understood. In this study, we show that the MarR type regulator, BmoR, regulates the expression of genes involved in the homeostasis of intracellular redox state. Transcriptome analysis showed that absence of BmoR leads to altered expression in total of 167 genes. Sixteen of these genes had a 2-fold or greater change in their expression. Most of these genes are related to LPS biosynthesis and carbohydrates metabolism, but there was a signifcant increase in the expression of genes related to the redox balance inside the cell. A pyridine nucleotide-disulfde oxidoreductase located directly upstream of bmoR was shown to be repressed by direct binding of BmoR to the promoter region. The expression of two other genes, coding for a thiosulphate:quinoneoxidoreductase and a thioredoxin, are indirectly afected by bmoR mutation during oxygen exposure. Phenotypic assays showed that BmoR is important to maintain the thiol/disulfde balance in the cell, confrming its relevance to B. fragilis response to oxidative stress