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Dominant, Heritable Resistance to Stewart's Wilt in Maize Is Associated with an Enhanced Vascular Defense Response to Infection with Pantoea stewartii.

  • Doblas-Ibáñez, Paula1
  • Deng, Kaiyue1
  • Vasquez, Miguel F1
  • Giese, Laura2
  • Cobine, Paul A3
  • Kolkman, Judith M4
  • King, Helen1
  • Jamann, Tiffany M5
  • Balint-Kurti, Peter6
  • De La Fuente, Leonardo7
  • Nelson, Rebecca J4
  • Mackey, David2
  • Smith, Laurie G1
  • 1 Section of Cell and Developmental Biology, University of California at San Diego, La Jolla, CA 92093, U.S.A.
  • 2 Department of Horticulture and Crop Sciences, The Ohio State University, Columbus, OH 43210, U.S.A.
  • 3 Department of Biological Sciences, Auburn University, Auburn, AL 36849, U.S.A.
  • 4 School of Integrative Plant Science, Cornell University, Ithaca, NY 14853, U.S.A.
  • 5 Department of Crop Sciences, University of Illinois Urbana-Champaign, Urbana, IL 61801, U.S.A.
  • 6 United States Department of Agriculture-Agricultural Research Service, Plant Science Research Unit, Raleigh, NC 27695, U.S.A. and Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, NC 27695, U.S.A. , (United States)
  • 7 Department of Entomology and Plant Pathology, Auburn University.
Published Article
Molecular Plant-Microbe Interactions
Scientific Societies
Publication Date
Dec 01, 2019
DOI: 10.1094/MPMI-05-19-0129-R
PMID: 31657672


Vascular wilt bacteria such as Pantoea stewartii, the causal agent of Stewart's bacterial wilt of maize (SW), are destructive pathogens that are difficult to control. These bacteria colonize the xylem, where they form biofilms that block sap flow leading to characteristic wilting symptoms. Heritable forms of SW resistance exist and are used in maize breeding programs but the underlying genes and mechanisms are mostly unknown. Here, we show that seedlings of maize inbred lines with pan1 mutations are highly resistant to SW. However, current evidence suggests that other genes introgressed along with pan1 are responsible for resistance. Genomic analyses of pan1 lines were used to identify candidate resistance genes. In-depth comparison of P. stewartii interaction with susceptible and resistant maize lines revealed an enhanced vascular defense response in pan1 lines characterized by accumulation of electron-dense materials in xylem conduits visible by electron microscopy. We propose that this vascular defense response restricts P. stewartii spread through the vasculature, reducing both systemic bacterial colonization of the xylem network and consequent wilting. Though apparently unrelated to the resistance phenotype of pan1 lines, we also demonstrate that the effector WtsE is essential for P. stewartii xylem dissemination, show evidence for a nutritional immunity response to P. stewartii that alters xylem sap composition, and present the first analysis of maize transcriptional responses to P. stewartii infection.

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