Differentially expressed proteins in the interaction of Xanthomonas axonopodis pv. citri with leaf extract of the host plant

Abstract

The present study reports the expression of proteins of Xanthomonas axonopodis pv. citri in response to different growth conditions. The bacterium was cultured in the basal medium MM1 and in the presence of leaf extracts from a susceptible host plant (sweet orange) as well as a resistant (ponkan) and a nonhost plant (passion fruit). The protein profiles were analyzed by two-dimensional gel electrophoresis (2-DE). Twelve differential spots (induced, up- and down-regulated and repressed) were observed in the protein profiles of the bacterium cultivated in citrus extract (susceptible host) when compared to that of MM1. The 2-DE profile of the bacterium cultured in the complex medium nutrient yeast glycerol was also obtained and the comparison with that of MM1 revealed 36 differential spots. Five proteins from the different treatments were successfully N-terminally sequenced and the putative functions were assigned by homology searches in databases. Two constitutively expressed proteins, B4 and B5, were identified as pseudouridine synthase and elongation factor P, respectively. The large subunit of ribulose 1,5-biphosphate carboxylase/oxygenase and a sulfate binding protein were found as specifically up-regulated in the presence of citrus extracts. Finally, the heat shock protein G was found exclusively in the complex medium and repressed in all other media.

Identification of differentially expressed genes of Xanthomonas axonopodis pv. citri by representational difference analysis of cDNA

“…After 12 h growth in NYG, X. axonopodis pv. citri is close to the stationary phase (Mehta and Rosato, 2001), which could explain the expression of the transposon ISXac3 in this treatment. In X. axonopodis pv.…”

“…The induction time and leaf extract concentration of the culture media were previously determined by Mehta and Rosato (2001) in the analysis of the differential expression of proteins of X. axonopodis pv citri. The bacterium was also recovered from host plant leaves 6 days after inoculation.…”

“…Also primers for the gene efp encoding the elongation factor P protein (XAC1849), which was constitutively expressed in the treatments MM1, MM1+leaf extract and NYG (Mehta and Rosato, 2001) was synthesized and used as a control. The RT-PCR reactions performed herein were not quantitative and therefore only the presence or absence of bands was considered.…”

“…Many of these genes may have been differentially expressed due to the difference in the presence of nutrients in the media used. The minimal medium MM1, used as a control is poor in nutrients and therefore the bacterium grows slowly, when compared to the other culture conditions (Mehta and Rosato, 2001). Peptides and amino acids, for example, are essential growth factors for several bacteria and enzymes such as peptidyl dipeptidase should be important for the degradation of proteins which are more abundant in the leaf extract, NYG and probably in vivo treatments.…”

The induction of differentially expressed proteins of Xylella fastidiosa with citrus extract

“…These metabolites may play a role in the interaction of plants with biotic and abiotic environmental factors (23). Other studies that supplemented bacterial culture media with plant leaf extract or plant flavonoids have shown that compounds derived from plant can stimulate differential expression of bacterial proteins (11,15).…”