title: The maize disease resistance gene Htn1 against northern corn leaf blight encodes a wall-associated receptor-like kinase.
abstract: Northern corn leaf blight (NCLB) caused by the hemibiotrophic fungus Exserohilum turcicum is an important foliar disease of maize that is mainly controlled by growing resistant maize cultivars. The Htn1 locus confers quantitative and partial NCLB resistance by delaying the onset of lesion formation. Htn1 represents an important source of genetic resistance that was originally introduced from a Mexican landrace into modern maize breeding lines in the 1970s. Using a high-resolution map-based cloning approach, we delimited Htn1 to a 131.7-kb physical interval on chromosome 8 that contained three candidate genes encoding two wall-associated receptor-like kinases (ZmWAK-RLK1 and ZmWAK-RLK2) and one wall-associated receptor-like protein (ZmWAK-RLP1). TILLING (targeting induced local lesions in genomes) mutants in ZmWAK-RLK1 were more susceptible to NCLB than wild-type plants, both in greenhouse experiments and in the field. ZmWAK-RLK1 contains a nonarginine-aspartate (non-RD) kinase domain, typically found in plant innate immune receptors. Sequence comparison showed that the extracellular domain of ZmWAK-RLK1 is highly diverse between different maize genotypes. Furthermore, an alternative splice variant resulting in a truncated protein was present at higher frequency in the susceptible parents of the mapping populations compared with in the resistant parents. Hence, the quantitative Htn1 disease resistance in maize is encoded by an unusual innate immune receptor with an extracellular wall-associated kinase domain. These results further highlight the importance of this protein family in resistance to adapted pathogens.
authors.affiliation: Institute of Plant Biology, University of Zurich, CH-8008 Zurich, Switzerland;
authors.forename: Severine
authors.initials: S
authors.lastname: Hurni
authors.affiliation: KWS SAAT SE, DE-37574 Einbeck, Germany.
authors.forename: Daniela
authors.initials: D
authors.lastname: Scheuermann
authors.affiliation: Institute of Plant Biology, University of Zurich, CH-8008 Zurich, Switzerland;
authors.forename: Simon G
authors.initials: SG
authors.lastname: Krattinger
authors.affiliation: KWS SAAT SE, DE-37574 Einbeck, Germany.
authors.forename: Bettina
authors.initials: B
authors.lastname: Kessel
authors.affiliation: Institute of Plant Biology, University of Zurich, CH-8008 Zurich, Switzerland;
authors.forename: Thomas
authors.initials: T
authors.lastname: Wicker
authors.affiliation: Institute of Plant Biology, University of Zurich, CH-8008 Zurich, Switzerland;
authors.forename: Gerhard
authors.initials: G
authors.lastname: Herren
authors.affiliation: Institute of Plant Biology, University of Zurich, CH-8008 Zurich, Switzerland;
authors.forename: Mirjam N
authors.initials: MN
authors.lastname: Fitze
authors.affiliation: Institute of Plant Biology, University of Zurich, CH-8008 Zurich, Switzerland;
authors.forename: James
authors.initials: J
authors.lastname: Breen
authors.affiliation: KWS SAAT SE, DE-37574 Einbeck, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Presterl
authors.affiliation: KWS SAAT SE, DE-37574 Einbeck, Germany bkeller@botinst.uzh.ch milena.ouzunova@kws.com.
authors.forename: Milena
authors.initials: M
authors.lastname: Ouzunova
authors.affiliation: Institute of Plant Biology, University of Zurich, CH-8008 Zurich, Switzerland; bkeller@botinst.uzh.ch milena.ouzunova@kws.com.
authors.forename: Beat
authors.initials: B
authors.lastname: Keller
mesh_terms: D001203:Ascomycota / Q000472:pathogenicity*; D017343:Genes, Plant; D008969:Molecular Sequence Data; D009154:Mutation; D011494:Protein Kinases / Q000235:genetics*; D003313:Zea mays / Q000201:enzymology / Q000382:microbiology*
chemical_list: D011494:Protein Kinases
keywords: Exserohilum turcicum; maize; pattern recognition receptor; quantitative disease resistance; wall-associated receptor-like kinase