The role of PP2C protein phosphatases in pattern- and effector- triggered immunity in tomato

Protein phosphorylation mediated by protein kinases is important in plant immune signaling transduction and has been extensively investigated. The reverse action of protein dephosphorylation via protein phosphatases, however, is less understood. Based on transcriptome data, we previously identified 14 tomato PP2C phosphatases that may be involved in pattern triggered immunity (PTI) or effector triggered immunity (ETI). We renamed these PP2C phosphatases as PP2C immunity-associated candidates (Pic). In the context of this current project, four Pic proteins were screened for their impact on resistance to the bacterial pathogen, Pseudomonas syringae pv. tomato (Pst). Using loss of function mutants, the role of four Pic proteins were characterized in terms of the overall impact on growth of Pst, as well as how they are related to the ROS production or the mitogen-activated protein kinase (MAPK) pathways. Additionally, we used an agrobacterium-mediated transient overexpression approach to further examine the function of Pic 5, Pic 10 and Pic 12 in the regulation of immune pathways. Our results showed that loss-of-function mutation in Pic 2, Pic 5 or Pic 10 did not significantly alter disease resistance to Pst, Also, ROS production and MAPK activation in these mutants were not affected. Interestingly, we found loss-of-function pic12 mutant had enhanced disease resistance to Pst. Our data further indicated that Pic12 might regulate both flagellin-dependent and independent immune pathways.

Spending this summer at the Boyce Thompson Institute has solidified my desire to pursue a PhD. Being so immersed in the research of the Martin Lab has enabled me to further realize topics that interest me and has given me ideas for topics to pursue in the future. Living in Ithaca, seeing the gorges and eating some of the best food I have ever eaten, has been an experience that I will never forget with individuals I hope to never lose touch with.