Genetic Architecture of Ear Fasciation in Maize (Zea mays) under QTL Scrutiny.
Knowledge of the genes affecting maize ear inflorescence may lead to better grain yield modeling. Maize ear fasciation, defined as abnormal flattened ears with high kernel row number, is a quantitative trait widely present in Portuguese maize landraces.


METHODS
Using a segregating population derived from an ear fasciation contrasting cross (consisting of 149 F2:3 families) we established a two location field trial using a complete randomized block design. Correlations and heritabilities for several ear fasciation-related traits and yield were determined. Quantitative Trait Loci (QTL) involved in the inheritance of those traits were identified and candidate genes for these QTL proposed.


CONCLUSIONS
Ear fasciation broad-sense heritability was 0.73. Highly significant correlations were found between ear fasciation and some ear and cob diameters and row number traits. For the 23 yield and ear fasciation-related traits, 65 QTL were identified, out of which 11 were detected in both environments, while for the three principal components, five to six QTL were detected per environment. Detected QTL were distributed across 17 genomic regions and explained individually, 8.7% to 22.4% of the individual traits or principal components phenotypic variance. Several candidate genes for these QTL regions were proposed, such as bearded-ear1, branched silkless1, compact plant1, ramosa2, ramosa3, tasselseed4 and terminal ear1. However, many QTL mapped to regions without known candidate genes, indicating potential chromosomal regions not yet targeted for maize ear traits selection.


CONCLUSIONS
Portuguese maize germplasm represents a valuable source of genes or allelic variants for yield improvement and elucidation of the genetic basis of ear fasciation traits. Future studies should focus on fine mapping of the identified genomic regions with the aim of map-based cloning.
Departamento de Ciências Agronómicas, Escola Superior Agrária de Coimbra, Instituto Politécnico de Coimbra, Coimbra, Portugal; Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal.
Pedro
P
Mendes-Moreira
Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal.
Mara L
ML
Alves
Faculty of Agriculture, Department of Seed Science and Technology, University of Zagreb, Zagreb, Croatia.
Zlatko
Z
Satovic
Departamento de Ciências Agronómicas, Escola Superior Agrária de Coimbra, Instituto Politécnico de Coimbra, Coimbra, Portugal.
João Pacheco
JP
Dos Santos
Departamento de Ciências Agronómicas, Escola Superior Agrária de Coimbra, Instituto Politécnico de Coimbra, Coimbra, Portugal.
João Nina
JN
Santos
Departamento de Biologia/UFLA, Universidade Federal de Lavras, Lavras-MG, Brasil.
João Cândido
JC
Souza
Fundação Bomfim, Braga, Portugal.
Silas E
SE
Pêgo
Department of Agronomy, Iowa State University, Ames, Iowa, United States of America.
Arnel R
AR
Hallauer
Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal.
Maria Carlota
MC
Vaz Patto
D002874:Chromosome Mapping; D032461:Chromosomes, Plant / Q000235:genetics; D010641:Phenotype; D010940:Plant Proteins / Q000235:genetics*; D040641:Quantitative Trait Loci / Q000235:genetics*; D000068098:Seed Bank; D003313:Zea mays / Q000235:genetics* / Q000254:growth & development
D010940:Plant Proteins