title: Hallauer's Tusón: a decade of selection for tropical-to-temperate phenological adaptation in maize.
abstract: Crop species exhibit an astounding capacity for environmental adaptation, but genetic bottlenecks resulting from intense selection for adaptation and productivity can lead to a genetically vulnerable crop. Improving the genetic resiliency of temperate maize depends upon the use of tropical germplasm, which harbors a rich source of natural allelic diversity. Here, the adaptation process was studied in a tropical maize population subjected to 10 recurrent generations of directional selection for early flowering in a single temperate environment in Iowa, USA. We evaluated the response to this selection across a geographical range spanning from 43.05° (WI) to 18.00° (PR) latitude. The capacity for an all-tropical maize population to become adapted to a temperate environment was revealed in a marked fashion: on average, families from generation 10 flowered 20 days earlier than families in generation 0, with a nine-day separation between the latest generation 10 family and the earliest generation 0 family. Results suggest that adaptation was primarily due to selection on genetic main effects tailored to temperature-dependent plasticity in flowering time. Genotype-by-environment interactions represented a relatively small component of the phenotypic variation in flowering time, but were sufficient to produce a signature of localized adaptation that radiated latitudinally, in partial association with daylength and temperature, from the original location of selection. Furthermore, the original population exhibited a maladaptive syndrome including excessive ear and plant heights along with later flowering; this was reduced in frequency by selection for flowering time.
authors.affiliation: Department of Plant and Soil Sciences, University of Delaware, Newark, DE, USA.
authors.forename: J E C
authors.initials: JE
authors.lastname: Teixeira
authors.affiliation: Department of Plant and Soil Sciences, University of Delaware, Newark, DE, USA.
authors.forename: T
authors.initials: T
authors.lastname: Weldekidan
authors.affiliation: Department of Agronomy, University of Wisconsin, Madison, WI, USA.
authors.forename: N
authors.initials: N
authors.lastname: de Leon
authors.affiliation: 1] USDA-ARS, Columbia, MO, USA [2] Division of Plant Sciences, University of Missouri, Columbia, MO, USA.
authors.forename: S
authors.initials: S
authors.lastname: Flint-Garcia
authors.affiliation: 1] USDA-ARS, Raleigh, NC, USA [2] Department of Crop Science, North Carolina State University, Raleigh, NC, USA.
authors.forename: J B
authors.initials: JB
authors.lastname: Holland
authors.affiliation: 1] USDA-ARS, Ames, IA, USA [2] Interdepartmental Genetics Graduate Program, Iowa State University, Ames, IA, USA.
authors.forename: N
authors.initials: N
authors.lastname: Lauter
authors.affiliation: Department of Soil and Crop Sciences, Texas A&M University, College Station, TX, USA.
authors.forename: S C
authors.initials: SC
authors.lastname: Murray
authors.affiliation: 1] Department of Soil and Crop Sciences, Texas A&M University, College Station, TX, USA [2] Lubbock Research and Extension Center, Texas A&M AgriLife Research, Lubbock, TX, USA.
authors.forename: W
authors.initials: W
authors.lastname: Xu
authors.affiliation: Interdepartmental Genetics Graduate Program, Iowa State University, Ames, IA, USA.
authors.forename: D A
authors.initials: DA
authors.lastname: Hessel
authors.affiliation: Department of Plant and Soil Sciences, University of Delaware, Newark, DE, USA.
authors.forename: A E
authors.initials: AE
authors.lastname: Kleintop
authors.affiliation: Department of Plant and Soil Sciences, University of Delaware, Newark, DE, USA.
authors.forename: J A
authors.initials: JA
authors.lastname: Hawk
authors.affiliation: Department of Agronomy, Iowa State University, Ames, IA, USA.
authors.forename: A
authors.initials: A
authors.lastname: Hallauer
authors.affiliation: Department of Plant and Soil Sciences, University of Delaware, Newark, DE, USA.
authors.forename: R J
authors.initials: RJ
authors.lastname: Wisser
mesh_terms: D000222:Adaptation, Physiological / Q000235:genetics*; D018556:Crops, Agricultural / Q000235:genetics; D035264:Flowers / Q000502:physiology; D059647:Gene-Environment Interaction; D005828:Genetics, Population; D016014:Linear Models; D008957:Models, Genetic; D010641:Phenotype; D017440:Photoperiod; D012641:Selection, Genetic; D013696:Temperature; D003313:Zea mays / Q000235:genetics* / Q000502:physiology