|CHAKRAVARTHY, SUMA - Cornell University - New York|
|BUTCHER, BRONWYN - Cornell University - New York|
|LIU, YINGYU - Cornell University - New York|
|D'AMICO, KATHERINE - Former ARS Employee|
|COSTER, MATTHEW - Cornell University - New York|
Submitted to: Molecular Plant Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/2/2017
Publication Date: 4/6/2017
Citation: Chakravarthy, S., Butcher, B., Liu, Y., D'Amico, K.M., Coster, M., Filiatrault, M.J. 2017. Virulence of Pseudomonas syringae pv. tomato DC3000 is influenced by the catabolite repression control protein Crc. Molecular Plant Pathology. 30(4):283-294.
Interpretive Summary: The catabolite repression control (crc) protein in Pseudomonas is a protein that controls the ability of the bacterium to preferentially utilize the most preferred carbon sources. In some bacteria, this protein has also been shown to contribute to other processes such as cell aggregation and virulence. To further elucidate the role of Crc in P. syringae, a Crc mutant was constructed. Our research revealed that when Crc was deleted from P. syringae the mutant showed increased ability to move across a surface (swarm) and increased ability to form cell aggregates (biofilm). Unexpectedly, we also discovered that deletion of Crc resulted in reduced virulence in a host plant and delayed hypersensitivity response in a non-host. The factors causing this reduced virulence are not yet known. The results of this study provide insight into the function of Crc in P. syringae and more broadly, provide new evidence for a link between metabolism and the ability of P. syringae to cause disease.
Technical Abstract: Pseudomonas syringae infects diverse plant species and is widely used as a model system in the study of effector function and the molecular basis of plant diseases. Although the relationship between bacterial metabolism, nutrient acquisition, and virulence has attracted increasing attention in bacterial pathology, it is largely unexplored in P. syringae. The Crc (catabolite repression control) protein is a putative RNA-binding protein that regulates carbon metabolism as well as a number of other factors in the pseudomonads. Here, we show that deletion of crc increased bacterial swarming motility and biofilm formation. The crc mutant showed reduced growth and symptoms in Arabidopsis and tomato when compared with the wild-type strain. We have evidence that the crc mutant shows delayed hypersensitive response (HR) when infiltrated into Nicotiana benthamiana and tobacco. Interestingly, the crcmutant was more susceptible to hydrogen peroxide, suggesting that, in planta, the mutant may be sensitive to reactive oxygen species generated during pathogen-associated molecular pattern–triggered immunity (PTI). Indeed, HR was further delayed when PTI-induced tissues were challenged with the crc mutant. The crc mutant did not elicit an altered PTI response in plants compared with the wild-type strain. We conclude that Crc plays an important role in growth and survival during infection.