title: QTL mapping and candidate genes for resistance to Fusarium ear rot and fumonisin contamination in maize.
abstract: Fusarium verticillioides is a common maize pathogen causing ear rot (FER) and contamination of the grains with the fumonisin B1 (FB1) mycotoxin. Resistance to FER and FB1 contamination are quantitative traits, affected by environmental conditions, and completely resistant maize genotypes to the pathogen are so far unknown. In order to uncover genomic regions associated to reduced FER and FB1 contamination and identify molecular markers for assisted selection, an F2:3population of 188 progenies was developed crossing CO441 (resistant) and CO354 (susceptible) genotypes. FER severity and FB1 contamination content were evaluated over 2 years and sowing dates (early and late) in ears artificially inoculated with F. verticillioides by the use of either side-needle or toothpick inoculation techniques.
  
  
  
  Weather conditions significantly changed in the two phenotyping seasons and FER and FB1 content distribution significantly differed in the F3progenies according to the year and the sowing time. Significant positive correlations (P < 0.01) were detected between FER and FB1 contamination, ranging from 0.72 to 0.81. A low positive correlation was determined between FB1 contamination and silking time (DTS). A genetic map was generated for the cross, based on 41 microsatellite markers and 342 single nucleotide polymorphisms (SNPs) derived from Genotyping-by-Sequencing (GBS). QTL analyses revealed 15 QTLs for FER, 17 QTLs for FB1 contamination and nine QTLs for DTS. Eight QTLs located on linkage group (LG) 1, 2, 3, 6, 7 and 9 were in common between FER and FB1, making possible the selection of genotypes with both low disease severity and low fumonisin contamination. Moreover, five QTLs on LGs 1, 2, 4, 5 and 9 located close to previously reported QTLs for resistance to other mycotoxigenic fungi. Finally, 24 candidate genes for resistance to F. verticillioides are proposed combining previous transcriptomic data with QTL mapping.
  
  
  
  This study identified a set of QTLs and candidate genes that could accelerate breeding for resistance of maize lines showing reduced disease severity and low mycotoxin contamination determined by F. verticillioides.
authors.affiliation: Department of Sustainable Crop Production, Università Cattolica del Sacro Cuore, Via Emilia Parmense 84, 29122, Piacenza, Italy.
authors.forename: Valentina
authors.initials: V
authors.lastname: Maschietto
authors.affiliation: Parco Tecnologico Padano, Via Einstein, Loc. Cascina Codazza, 26900, Lodi, Italy.
authors.forename: Cinzia
authors.initials: C
authors.lastname: Colombi
authors.affiliation: Parco Tecnologico Padano, Via Einstein, Loc. Cascina Codazza, 26900, Lodi, Italy.|Institute of Agricultural Biology and Biotechnology, CNR, Via Bassini 15, 20133, Milano, Italy.
authors.forename: Raul
authors.initials: R
authors.lastname: Pirona
authors.affiliation: Parco Tecnologico Padano, Via Einstein, Loc. Cascina Codazza, 26900, Lodi, Italy.
authors.forename: Giorgio
authors.initials: G
authors.lastname: Pea
authors.affiliation: Parco Tecnologico Padano, Via Einstein, Loc. Cascina Codazza, 26900, Lodi, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Strozzi
authors.affiliation: Department of Sustainable Crop Production, Università Cattolica del Sacro Cuore, Via Emilia Parmense 84, 29122, Piacenza, Italy.
authors.forename: Adriano
authors.initials: A
authors.lastname: Marocco
authors.affiliation: Parco Tecnologico Padano, Via Einstein, Loc. Cascina Codazza, 26900, Lodi, Italy. laura.rossini@unimi.it.|Department of Agricultural and Environmental Sciences Production, Landscape, Agroenergy, Università degli Studi di Milano, Via Celoria 2, 20133, Milano, Italy. laura.rossini@unimi.it.
authors.forename: Laura
authors.initials: L
authors.lastname: Rossini
authors.affiliation: Department of Sustainable Crop Production, Università Cattolica del Sacro Cuore, Via Emilia Parmense 84, 29122, Piacenza, Italy. alessandra.lanubile@unicatt.it.
authors.forename: Alessandra
authors.initials: A
authors.lastname: Lanubile
mesh_terms: D037341:Fumonisins / Q000378:metabolism*; D005670:Fusarium / Q000502:physiology*; D005838:Genotype; D018895:Microsatellite Repeats / Q000235:genetics; D010935:Plant Diseases / Q000235:genetics / Q000382:microbiology; D020641:Polymorphism, Single Nucleotide / Q000235:genetics; D040641:Quantitative Trait Loci; D003313:Zea mays / Q000235:genetics* / Q000378:metabolism / Q000382:microbiology*
chemical_list: D037341:Fumonisins; C056933:fumonisin B1
keywords: FB1 contamination; Fusarium verticillioides; Genotyping-by-Sequencing; Zea mays