International Symposium on Cereal Leaf Blights 2019 | University College Dublin, Ireland | 22-24 May 2019

Insights into the genetics of host-pathogen interactions for septoria nodorum blotch in Norwegian wheat fields and implications for resistance breeding

Morten Lillemo*
Norwegian University of Life Sciences

Anja Karine Ruud
Norwegian University of Life Sciences
Aarhus University

Min Lin
Norwegian University of Life Sciences

Andrea Ficke
Norwegian Institute of Bioeconomy Research

Jon Arne Dieseth
Graminor AS

Oral Presentation
Host Genetics and Resistance Breeding

Moore Auditorium, UCD O'Brien centre for Science
24 May 2019, 10:20

View this abstract online by visting

Septoria nodorum blotch (SNB), caused by Parastagonospora nodorum is a major wheat disease in many humid and temperate production areas. In Norway, it is the most important of the leaf blotch diseases, although it often occurs together with septoria tritici blotch (caused by Zymoseptoria tritici) and tan spot (caused by Pyrenophora tritici-repentis). Insufficient resistance in current cultivars makes farmers highly dependent on fungicides for disease control. Resistance breeding based on phenotypic selection has been slow due to the quantitative nature of the resistance, confounding effects of plant height and phenology on disease symptoms and a poor understanding of the underlying genetic mechanisms. In recent years, substantial progress has been made in understanding SNB at the molecular level of both host and pathogen. The discovery of necrotrophic effectors (NEs) that cause susceptibility by interacting with corresponding host sensitivity genes pointed to the screening of breeding material for NE-sensitivities as a promising breeding strategy. On this background, research efforts were initiated in Norway in 2009 to characterize the local pathogen population, investigate the role of NEs in causing susceptibility under field conditions and map major resistance/susceptibility loci in relevant wheat germplasm. This research revealed a highly diverse locally adapted pathogen population with an effector-gene repertoire highly suited to match the prevalent Tsn1 and Snn3 sensitivity alleles in current wheat cultivars and breeding lines. A reliable field testing methodology based on naturally infected straw and mist irrigation was established, and has been used to screen germplasm and phenotype mapping populations and association mapping panels of both spring and winter wheat. Tox3 sensitivity was revealed as a major factor for field susceptibility to SNB in ToxA and Tox1 insensitive germplasm, and several promising quantitative trait loci (QTL) for field resistance have been detected in genome-wide association studies and QTL mapping in MAGIC populations.