The Xanthomonas effector XopL uncovers the role of microtubules in stromule extension and dynamics in Nicotiana benthamiana

Jessica L. Erickson, Norman Adlung, Christina Lampe, Ulla Bonas, Martin H. Schattat

Research output: Contribution to journalArticleScientificpeer-review

36 Citations (Scopus)


Xanthomonas campestris pv. vesicatoria type III-secreted effectors were screened for candidates influencing plant cell processes relevant to the formation and maintenance of stromules in Nicotiana benthamiana lower leaf epidermis. Transient expression of XopL, a unique type of E3 ubiquitin ligase, led to a nearly complete elimination of stromules and the relocation of plastids to the nucleus. Further characterization of XopL revealed that the E3 ligase activity is essential for the two plastid phenotypes. In contrast to the XopL wild type, a mutant XopL lacking E3 ligase activity specifically localized to microtubules. Interestingly, mutant XopL-labeled filaments frequently aligned with stromules, suggesting an important, yet unexplored, microtubule–stromule relationship. High time-resolution movies confirmed that microtubules provide a scaffold for stromule movement and contribute to stromule shape. Taken together, this study has defined two populations of stromules: microtubule-dependent stromules, which were found to move slower and persist longer, and microtubule-independent stromules, which move faster and are transient. Our results provide the basis for a new model of stromule dynamics including interactions with both actin and microtubules.

Original languageEnglish
Pages (from-to)856-870
JournalThe Plant Journal
Issue number5
Publication statusPublished - Mar 2018
MoE publication typeA1 Journal article-refereed


  • actin
  • E3 ubiquitin ligase
  • microtubules
  • Nicotiana benthamiana
  • stromule dynamics
  • stromule morphology
  • stromule velocity
  • Xanthomonas campestris pv. vesicatoria
  • XopL
  • Tobacco/cytology
  • Actin Cytoskeleton/metabolism
  • Thiazolidines/pharmacology
  • Dinitrobenzenes/pharmacology
  • Plant Cells
  • Microtubules/metabolism
  • Bridged Bicyclo Compounds, Heterocyclic/pharmacology
  • Sulfanilamides/pharmacology
  • Bacterial Proteins/genetics
  • Plants, Genetically Modified
  • Green Fluorescent Proteins/genetics
  • Xanthomonas campestris/metabolism
  • Mutation
  • Plastids/metabolism
  • Ubiquitin-Protein Ligases/genetics


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