|LIU, ZHAOHUI - North Dakota State University|
|BRUEGGEMAN, ROBERT - North Dakota State University|
Submitted to: Molecular Plant Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/11/2014
Publication Date: 7/11/2014
Publication URL: http://handle.nal.usda.gov/10113/60212
Citation: Liu, Z., Holmes, D.J., Faris, J.D., Chao, S., Brueggeman, R., Edwards, M.C., Friesen, T.L. 2015. Necrotrophic effector-triggered susceptibility (NETS) underlies the barley-Pyrenophora teres f. teres interaction specific to chromosome 6H. Molecular Plant Pathology. 16(2):188-200.
Interpretive Summary: Net form net blotch of barley is caused by Pyrenophora teres f. teres which induces major yield and quality losses to farmers annually. Our overall understanding of the disease interaction is limited. In this study we identified a necrotrophic effector (NE) that is produced by the pathogen during disease induction. A barley population was developed and genotyped to be used in locating the genomic region responsible for sensitivity to this newly identified NE (PttNE1) and susceptibility to a diverse set of P. teres f. teres isolates. The host gene, designated SPN1 conditioning sensitivity to PttNE1 mapped to barley chromosome 6H. The PttNE1-SPN1 interaction was accounted for a significant portion of disease caused by various P. teres f. teres isolates. The compatible (susceptible) interaction was also characterized by hallmarks of a biotrophic resistance response including strong accumulation of hydrogen peroxide and cell membrane disruption. Our observations indicate that the barley-P teres f. teres pathosystem does, at least partially, follow an inverse gene-for-gene/necrotrophic effector-triggered susceptibility (NETS) model.
Technical Abstract: Barley net form net blotch, caused by Pyrenophora teres f. teres, is a destructive foliar disease in barley-growing regions worldwide. Our overall understanding of the genetic and molecular basis of the barley- P. teres f. teres interaction is limited. Intercellular wash fluids (IWF) from infected barley were used to identify a necrotrophic effector (NE) produced by the pathogen in planta. The proteinaceous nature and size of the fungal effector was determined by protease treatment and HPLC gel filtration. A barley recombinant inbred line population was developed and genotyped to map sensitivity to the NE and evaluate susceptibility to a diverse set of P. teres f. teres isolates. For the first time, a P. teres f. teres NE, (PttNE1) and the corresponding host sensitivity gene, SPN1 (sensitivity to PttNE1) was identified. A major disease QTL for five geographically diverse isolates mapped to barley chromosome 6H and peaked directly over the SPN1 locus. However, not all isolates tested produced a 6H QTL indicating diversity in the pathogen population. The compatible (susceptible) interaction was characterized by strong accumulation of reactive oxygen and increased levels of electrolyte leakage, indicative of a programmed cell death respopnse. Our observations indicate that the barley-P teres f. teres pathosystem does, at least partially, follow an inverse gene-for-gene/necrotrophic effector-triggered susceptibility (NETS) model.