Hydathode immunity protects the Arabidopsis leaf vasculature against colonization by bacterial pathogens

Misha Paauw, Marieke van Hulten, Sayantani Chatterjee, Jeroen A. Berg, Nanne W. Taks, Marcel Giesbers, Manon M.S. Richard, Harrold A. van den Burg*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

7 Citations (Scopus)

Abstract

Plants prevent disease by passively and actively protecting potential entry routes against invading microbes. For example, the plant immune system actively guards roots, wounds, and stomata. How plants prevent vascular disease upon bacterial entry via guttation fluids excreted from specialized glands at the leaf margin remains largely unknown. These so-called hydathodes release xylem sap when root pressure is too high. By studying hydathode colonization by both hydathode-adapted (Xanthomonas campestris pv. campestris) and non-adapted pathogenic bacteria (Pseudomonas syringae pv. tomato) in immunocompromised Arabidopsis mutants, we show that the immune hubs BAK1 and EDS1-PAD4-ADR1 restrict bacterial multiplication in hydathodes. Both immune hubs effectively confine bacterial pathogens to hydathodes and lower the number of successful escape events of an hydathode-adapted pathogen toward the xylem. A second layer of defense, which is dependent on the plant hormones' pipecolic acid and to a lesser extent on salicylic acid, reduces the vascular spread of the pathogen. Thus, besides glands, hydathodes represent a potent first line of defense against leaf-invading microbes.

Original languageEnglish
Pages (from-to)697-710
JournalCurrent biology : CB
Volume33
Issue number4
DOIs
Publication statusPublished - 27 Feb 2023

Keywords

  • BAK1
  • Brassinosteroid-insensitive 1-associated receptor kinase 1
  • guttation
  • host entry
  • hydathode
  • pipecolic acid
  • plant immunity
  • vascular pathogen
  • Xanthomonas campestris pv. campestris

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