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Research Project: Genetics of Disease Resistance and Food Quality Traits in Corn

Location: Plant Science Research

Title: Dominant, heritable resistance to Stewart’s wilt in maize is associated with an enhanced vascular defense response to infection with P. stewartii

Author
item DOBLAS-IBANEZ, PAULA - University Of California
item DENG, KAIYUE - University Of California
item VASQUEZ, MIGUEL - University Of California
item GIESE, LAURA - The Ohio State University
item COBINE, PAUL - Auburn University
item KOLKMAN, JUDITH - Cornell University - New York
item KING, HELEN - University Of California
item JAMANN, TIFFANY - University Of Illinois
item Balint-Kurti, Peter
item DE LA FUENTE, LEONARDO - Auburn University
item NELSON, REBECCA - Cornell University - New York
item MACKEY, DAVID - The Ohio State University
item SMITH, LAURIE - University Of California

Submitted to: Molecular Plant-Microbe Interactions
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/1/2019
Publication Date: 8/1/2019
Citation: Doblas-Ibanez, P., Deng, K., Vasquez, M., Giese, L., Cobine, P., Kolkman, J., King, H., Jamann, T., Balint Kurti, P.J., De La Fuente, L., Nelson, R., Mackey, D., Smith, L. 2019. Dominant, heritable resistance to Stewart’s wilt in maize is associated with an enhanced vascular defense response to infection with P. stewartii. Molecular Plant-Microbe Interactions. 32:1581-1597.

Interpretive Summary: In this manuscript we show that a dominant, heritable resistance to Stewart’s wilt in maize is associated with an enhanced response to infection with P. stewartii, the bacteria that causes Stewart’s wilt, in the vasculature.

Technical Abstract: Vascular wilt bacteria, such as Pantoea stewartii, the causal agent of Stewart’s 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 but the underlying genes and mechanisms are unknown. We show that seedlings of maize lines with pan1 mutations are highly resistant to SW. However current evidence suggests that other gene(s) 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 lines reveals an enhanced vascular defense response in pan1 lines characterized by accumulation of electron-dense materials visible by electron microscopy in xylem conduits. 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 WtsE effector 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. Together, our results provide a variety of new insights into P. stewartii – maize pathosystem.