title: An Improved Method for Measuring Quantitative Resistance to the Wheat Pathogen Zymoseptoria tritici Using High-Throughput Automated Image Analysis.
abstract: Zymoseptoria tritici causes Septoria tritici blotch (STB) on wheat. An improved method of quantifying STB symptoms was developed based on automated analysis of diseased leaf images made using a flatbed scanner. Naturally infected leaves (n = 949) sampled from fungicide-treated field plots comprising 39 wheat cultivars grown in Switzerland and 9 recombinant inbred lines (RIL) grown in Oregon were included in these analyses. Measures of quantitative resistance were percent leaf area covered by lesions, pycnidia size and gray value, and pycnidia density per leaf and lesion. These measures were obtained automatically with a batch-processing macro utilizing the image-processing software ImageJ. All phenotypes in both locations showed a continuous distribution, as expected for a quantitative trait. The trait distributions at both sites were largely overlapping even though the field and host environments were quite different. Cultivars and RILs could be assigned to two or more statistically different groups for each measured phenotype. Traditional visual assessments of field resistance were highly correlated with quantitative resistance measures based on image analysis for the Oregon RILs. These results show that automated image analysis provides a promising tool for assessing quantitative resistance to Z. tritici under field conditions.
authors.affiliation: First, fifth, and sixth authors: Plant Pathology, Institute of Integrative Biology, ETH Zürich, Zürich; second and fourth authors: Department of Botany and Plant Pathology, Oregon State University, Corvallis; and third author: Theoretical Biology, Institute of Integrative Biology, ETH Zürich.
authors.forename: Ethan L
authors.initials: EL
authors.lastname: Stewart
authors.affiliation: First, fifth, and sixth authors: Plant Pathology, Institute of Integrative Biology, ETH Zürich, Zürich; second and fourth authors: Department of Botany and Plant Pathology, Oregon State University, Corvallis; and third author: Theoretical Biology, Institute of Integrative Biology, ETH Zürich.
authors.forename: Christina H
authors.initials: CH
authors.lastname: Hagerty
authors.affiliation: First, fifth, and sixth authors: Plant Pathology, Institute of Integrative Biology, ETH Zürich, Zürich; second and fourth authors: Department of Botany and Plant Pathology, Oregon State University, Corvallis; and third author: Theoretical Biology, Institute of Integrative Biology, ETH Zürich.
authors.forename: Alexey
authors.initials: A
authors.lastname: Mikaberidze
authors.affiliation: First, fifth, and sixth authors: Plant Pathology, Institute of Integrative Biology, ETH Zürich, Zürich; second and fourth authors: Department of Botany and Plant Pathology, Oregon State University, Corvallis; and third author: Theoretical Biology, Institute of Integrative Biology, ETH Zürich.
authors.forename: Christopher C
authors.initials: CC
authors.lastname: Mundt
authors.affiliation: First, fifth, and sixth authors: Plant Pathology, Institute of Integrative Biology, ETH Zürich, Zürich; second and fourth authors: Department of Botany and Plant Pathology, Oregon State University, Corvallis; and third author: Theoretical Biology, Institute of Integrative Biology, ETH Zürich.
authors.forename: Ziming
authors.initials: Z
authors.lastname: Zhong
authors.affiliation: First, fifth, and sixth authors: Plant Pathology, Institute of Integrative Biology, ETH Zürich, Zürich; second and fourth authors: Department of Botany and Plant Pathology, Oregon State University, Corvallis; and third author: Theoretical Biology, Institute of Integrative Biology, ETH Zürich.
authors.forename: Bruce A
authors.initials: BA
authors.lastname: McDonald
mesh_terms: D000383:Agriculture / Q000379:methods*; D001203:Ascomycota / Q000502:physiology*; D057166:High-Throughput Screening Assays / Q000379:methods*; D057865:Plant Immunity; D014908:Triticum / Q000276:immunology* / Q000382:microbiology