Abstract Fusarium head blight (FHB), an important disease of barley in many areas of the world, causes loss- es in grain yield and quality. Deoxynivalenol (DON) my- cotoxin residues, produced by the primary pathogen Fu- sarium graminearum, pose potential health risks. Barley producers may not be able to profitably market FHB-in- fected barley, even though it has a low DON level. Three types of FHB resistance have been described in wheat: Type I (penetration), Type II (spread), and Type III (my- cotoxin degradation). We describe putative measures of these three types of resistance in barley. In wheat, the three resistance mechanisms show quantitative inherit- ance. Accordingly, to study FHB resistance in barley, we used quantitative trait locus (QTL) mapping to determine the number, genome location, and effects of QTLs asso- ciated with Type-I and -II resistance and the concentra- tion of DON in the grain. We also mapped QTLs for plant height, heading date, and morphological attributes of the inflorescence (seeds per inflorescence, inflores- cence density, and lateral floret size). QTL analyses were based on a mapping population of F 1 -derived doubled- haploid (DH) lines from the cross of the two-rowed ge- notypes Gobernadora and CMB643, a linkage map con- structed with RFLP marker loci, and field evaluations of the three types of FHB resistance performed in China, Mexico, and two environments in North Dakota, USA. Resistance QTLs were detected in six of the seven link- age groups. Alternate favorable alleles were found at the same loci when different inoculation techniques were used to measure Type-I resistance. The largest-effect re- sistance QTL (for Type-II resistance) was mapped in the centromeric region of chromosome 2. All but two of the resistance QTLs coincided with QTLs determining mor- phological attributes of the inflorescence and/or plant height. Additional experiments are needed to determine if these coincident QTLs are due to linkage or pleiotropy and to more clearly define the biological basis of the FHB resistance QTLs. Plant architecture should be con- sidered in FHB resistance breeding efforts, particularly those directed at resistance QTL introgression and/or pyramiding. Key words Barley · Fusarium head blight (FHB) · QTL mapping · Plant architecture Introduction Fusarium head blight (FHB), caused by a number of Fu- sarium species (principally Fusarium graminearum) is an important disease of cereals in environments with prolonged wet climatic conditions from flowering Communicated by M.A. Saghai Maroof Oregon Agricultural Experiment Station Journal No. 11456 H. Zhu Crop Biotechnology Center, Texas A&M University, College Station, TX 77843, USA L. Gilchrist · H. Vivar ICARDA/CIMMYT, Apdo. Postal 6-641, 06600, Mexico, D.F., Mexico P. Hayes ( ✉ ) Department of Crop and Soil Science, Oregon State University, Corvallis, OR 97331, USA A. Kleinhofs · D. Kudrna Department of Agronomy and Soil Science, Washington State University, Pullman, WA 99164, USA Z. Liu Institute of Plant Protection, Shanghai Academy of Agricultural Sciences, Shangai, 201106, China L. Prom Department of Plant Pathology, University of Arkansas, Fayetteville, AR 72701, USA B. Steffenson Department of Plant Pathology, North Dakota State University, Fargo, ND 58015, USA T. Toojinda DNA fingerprinting Unit, National Research Center for Genetic Engineering and Biotechnology, Kasetsart University, Kampangsaen, Nakorn Prathom, Thailand Theor Appl Genet (1999) 99:1221–1232 © Springer-Verlag 1999 ORIGINAL ARTICLE H. Zhu · L. Gilchrist · P. Hayes · A. Kleinhofs D. Kudrna · Z. Liu · L. Prom · B. Steffenson T. Toojinda · H. Vivar Does function follow form? Principal QTLs for Fusarium head blight (FHB) resistance are coincident with QTLs for inflorescence traits and plant height in a doubled-haploid population of barley Received: 22 November 1998 / Accepted: 2 June 1999