Fungal resistance mediated by maize wall-associated kinase ZmWAK-RLK1 correlates with reduced benzoxazinoid content.

Abstract

Wall-associated kinases (WAKs) have recently been identified as major components of fungal and bacterial disease resistance in several cereal crop species. However, the molecular mechanisms of WAK-mediated resistance remain largely unknown. Here, we investigated the function of the maize gene ZmWAK-RLK1 (Htn1) that confers quantitative resistance to northern corn leaf blight (NCLB) caused by the hemibiotrophic fungal pathogen Exserohilum turcicum. ZmWAK-RLK1 was found to localize to the plasma membrane and its presence resulted in a modification of the infection process by reducing pathogen penetration into host tissues. A large-scale transcriptome analysis of near-isogenic lines (NILs) differing for ZmWAK-RLK1 revealed that several differentially expressed genes are involved in the biosynthesis of the secondary metabolites benzoxazinoids (BXs). The contents of several BXs including DIM2 BOA-Glc were significantly lower when ZmWAK-RLK1 is present. DIM2 BOA-Glc concentration was significantly elevated in ZmWAK-RLK1 mutants with compromised NCLB resistance. Maize mutants that were affected in overall BXs biosynthesis or content of DIM2 BOA-Glc showed increased NCLB resistance. We conclude that Htn1-mediated NCLB resistance is associated with a reduction of BX secondary metabolites. These findings suggest a link between WAK-mediated quantitative disease resistance and changes in biochemical fluxes starting with indole-3-glycerol phosphate.

• Authors: Ping Yang, Coraline Praz, Beibei Li, Jyoti Singla, Christelle A M Robert, Bettina Kessel, Daniela Scheuermann, Linda Lüthi, Milena Ouzunova, Matthias Erb, Simon G Krattinger, Beat Keller
• Journal: The New phytologist (New Phytol) Vol. 221 Issue 2 Pg. 976-987 (01 2019) ISSN: 1469-8137 [Electronic] England
• PMID: 30178602 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: © 2018 The Authors. New Phytologist © 2018 New Phytologist Trust.

Chemical References

• Benzoxazines

Topics

• Ascomycota (physiology)
• Benzoxazines (metabolism)
• Disease Resistance
• Plant Diseases (immunology, microbiology)
• Zea mays (enzymology, genetics, immunology, microbiology)