Project description:Pseudomonas syringae is an important plant pathogen that infects a wide variety of crops. The mgo (mangotoxin-generating operon) gene cluster produces an extracellular signaling molecule, leudiazen, and is highly conserved in Pseudomonas syringae strains. Here, we genetically removed mgo in Pseudomonas syringae pv. syringae (Pss) UMAF0158 to interrogate its impacts on bacterial infection. Loss of mgo not only alleviated the chlorosis symptom caused by Pss UMAF0158 infection, but also reduced bacterial population in tomato leaflets. Structure-activity relationship revealed that the diazeniumdiolate group and the isobutyl side chain of leudiazen are critical for its signaling activity. Through global transcriptome analysis, we found that mgo regulates the expression of a new gene cluster in addition to mangotoxin biosynthetic operon, namely RS17235-RS17245. This new gene cluster contributes to in planta survival of Pss UMAF0158 and is widely distributed in Pseudomonas syringae strains. Our results demonstrate that chemical signaling systems in plant pathogens play prominent roles in virulence and population increase and set stages for understanding downstream components of mgo-regulated signaling pathways.
Project description:We implemented transcriptional analysis methods using cDNA and high-throughput sequencing data to identify HrpL-regulated genes for six strains of Pseudomonas syringae
Project description:To further determine the origin of the increased virulence of Pseudomonas aeruginosa PA14 compared to Pseudomonas aeruginosa PAO1, we report a transcriptomic approach through RNA sequencing. Next-generation sequencing (NGS) has revolutioned sistems-based analsis of transcriptomic pathways. The goals of this study are to compare the transcriptomic profile of all 5263 orthologous genes of these nearly two strains of Pseudomonas aeruginosa.
Project description:Pseudomonas sp. GM16 associates with Populus, a model plant in biofuel production. Populus releases abundant phenolic glycosides such as salicin, but Pseudomonas sp. GM16 cannot utilize salicin whereas Pseudomonas strains are known to utilize compounds similar to the aglycone moiety of salicin – salicyl alcohol. We propose that the association of Pseudomonas to Populus is mediated by another organism (such as Rahnella sp. OV744) that degrades the glucosyl group of salicin. In this study, we demonstrate that in the Rahnella-Pseudomonas salicin co-culture model, Rahnella grows by degrading salicin to glucose 6-phosphate and salicyl alcohol which is secreted out and is subsequently utilized by Pseudomonas for its growth. Using various quantitative approaches, we elucidate the individual pathways for salicin and salicyl alcohol metabolism present in Rahnella and Pseudomonas, respectively. Furthermore, we were able to establish that the salicyl alcohol cross-feeding interaction between the two strains on salicin medium is carried out through combination of their respective individual pathways. The research presents one of the potential advantages of salicyl alcohol release by strains such as Rahnella, and how phenolic glycosides could be involved in attracting multiple types of bacteria into the Populus microbiome.
Project description:We implemented transcriptional analysis methods using cDNA and high-throughput sequencing data to identify HrpL-regulated genes for six strains of Pseudomonas syringae Each Pseudomonas syringae strains was transformed with either pBAD::EV or pBAD containing native hrpL sequence. Strains were grown in MM media supplemented with arabinose and collected 1, 3, and 5 hours post arabinose treatment. RNA was extracted for each time point and mixed at a 1/3 ratio. After removal of rRNA, double stranded cDNA was generated and library prepared accordeing to Illumina protocols.
