'Candidatus Liberibacter solanacearum' (Lso) is a devastating bacterial pathogen of crops transmitted by psyllids. Previously, a link between changes in ubiquitination and the progression of diseases caused by Lso was established. Among the Lso haplotypes, LsoA and LsoB infect solanaceous crops. LsoA induces chlorosis and stunting in tomato, while LsoB infection leads to more severe symptoms, including plant death. To better characterize the molecular basis of the differences in the diseases caused by these haplotypes, we cataloged the ubiquitinome of tomato leaves four weeks after LsoA and LsoB-infection and following infestation with Lso-free psyllids. Our analysis revealed haplotype-specific changes in the plant ubiquitinome. Gene Ontology (GO) terms related to glucose metabolism and proteasome-mediated ubiquitin-dependent protein catabolism were enriched among the differentially ubiquitinated proteins between LsoA-infected and Lso-free infested plants. Additionally, a KEGG pathway analysis determined an overrepresentation of proteins involved in carbon metabolism and fixation via the Calvin cycle. In contrast, the comparison of LsoB-infected and Lso-free infested plants revealed a broader range of enriched GO terms and KEGG pathways, including those associated with carbohydrate and energy metabolism, proteasome activity, and oxidative stress. These results contribute to our understanding of the development of Liberibacter-related diseases and reveal the importance of ubiquitin-related pathways in Lso infection. They also contribute to the expanding inventory of ubiquitinated proteins.
Levy et al. (Mon,) studied this question.