Association mapping for cold tolerance in two large maize inbred panels.
Breeding for cold tolerance in maize promises to allow increasing growth area and production in temperate zones. The objective of this research was to conduct genome-wide association analyses (GWAS) in temperate maize inbred lines and to find strategies for pyramiding genes for cold tolerance. Two panels of 306 dent and 292 European flint maize inbred lines were evaluated per se and in testcrosses under cold and control conditions in a growth chamber. We recorded indirect measures for cold tolerance as the traits number of days from sowing to emergence, relative leaf chlorophyll content or quantum efficiency of photosystem II. Association mapping for identifying genes associated to cold tolerance in both panels was based on genotyping with 49,585 genome-wide single nucleotide polymorphism (SNP) markers.



We found 275 significant associations, most of them in the inbreds evaluated per se, in the flint panel, and under control conditions. A few candidate genes coincided between the current research and previous reports. A total of 47 flint inbreds harbored the favorable alleles for six significant quantitative trait loci (QTL) detected for inbreds per se evaluated under cold conditions, four of them had also the favorable alleles for the main QTL detected from the testcrosses. Only four dent inbreds (EZ47, F924, NK807 and PHJ40) harbored the favorable alleles for three main QTL detected from the evaluation of the dent inbreds per se under cold conditions. There were more QTL in the flint panel and most of the QTL were associated with days to emergence and ΦPSII.



These results open new possibilities to genetically improve cold tolerance either with genome-wide selection or with marker assisted selection.
Misión Biológica de Galicia, Spanish National Research Council (CSIC), PO Box 2836080, Pontevedra, Spain. previlla@mbg.csic.es.
Pedro
P
Revilla
Misión Biológica de Galicia, Spanish National Research Council (CSIC), PO Box 2836080, Pontevedra, Spain.
Víctor Manuel
VM
Rodríguez
Misión Biológica de Galicia, Spanish National Research Council (CSIC), PO Box 2836080, Pontevedra, Spain.
Amando
A
Ordás
INRA, UMR de Génétique Végétale/Université Paris-Sud - CNRS - AgroParisTech, Gif-sur-Yvette, France.
Renaud
R
Rincent
INRA, UMR de Génétique Végétale/Université Paris-Sud - CNRS - AgroParisTech, Gif-sur-Yvette, France.
Alain
A
Charcosset
UMR INRA/USTL 1281 Stress Abiotiques et Différenciation des Végetaux cultivés, Péronne, France.
Catherine
C
Giauffret
Institute of Plant Breeding, Seed Science and Population Genetics, Universität Hohenheim, Stuttgart, Germany.
Albrecht E
AE
Melchinger
Plant Breeding, Technische Universität München, Freising, Germany.
Chris-Carolin
CC
Schön
Plant Breeding, Technische Universität München, Freising, Germany.
Eva
E
Bauer
Molecular Genetics, Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Gatersleben, Germany.
Thomas
T
Altmann
INRA-VERSAILLES, Evry, France.
Dominique
D
Brunel
Centro Investigacións Agrarias Mabegondo (CIAM), A Coruña, Spain.
Jesús
J
Moreno-González
Centro Investigacións Agrarias Mabegondo (CIAM), A Coruña, Spain.
Laura
L
Campo
KWS SAAT AG, Einbeck, Germany.
Milena
M
Ouzunova
Estación Experimental de Aula Dei (CSIC), Saragossa, Spain.
Ángel
Á
Álvarez
NEIKER-Instituto Vasco de Investigación y Desarrollo Agrario, Vitoria, Spain.
José Ignacio
JI
Ruíz de Galarreta
INRA, Stn Expt Mais, F-40590, St Martin De Hinx, France.
Jacques
J
Laborde
Misión Biológica de Galicia, Spanish National Research Council (CSIC), PO Box 2836080, Pontevedra, Spain.
Rosa Ana
RA
Malvar
D000483:Alleles; D002874:Chromosome Mapping; D032461:Chromosomes, Plant / Q000235:genetics; D003080:Cold Temperature; D003433:Crosses, Genetic; D055106:Genome-Wide Association Study; D005838:Genotype; D015810:Linkage Disequilibrium / Q000235:genetics; D020641:Polymorphism, Single Nucleotide / Q000235:genetics; D040641:Quantitative Trait Loci / Q000235:genetics; D013312:Stress, Physiological / Q000235:genetics*; D003313:Zea mays / Q000235:genetics*
Chilling; Cold tolerance; GWAS, Maize; QTL