Genetic Architecture of Ear Fasciation in Maize (Zea mays) under QTL Scrutiny

Abstract

Maize ear fasciationKnowledge 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.Material and MethodsUsing 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.Results and DiscussionEar 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.ConclusionsPortuguese 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.

Maize participatory breeding in Portugal: Comparison of farmer's and breeder's on‐farm selection

“…Indeed, very high correlations among cob diameter 3 and row number 1, with ear diameter 3, have been described in the present study (>0.90) and in Mendes‐Moreira et al. () (>0.80) in comparison with Hallauer et al. () (>0.67).…”

“…Locus umc1823, significantly deviated from Hardy–Weinberg equilibrium only for the BS cycles, is located at bin 2.02, where several genes potentially associated with traits consistently changing with the BS have been identified in previous studies (Mendes‐Moreira et al., ). This is the case of the QTLs for cob diameter 14 ( qcobd14 ) and kernel‐row number 6, 26 ( qkrow6, 26 ) (Lawrence et al., ).…”

“…These were all genomic SSRs and all with an excess of homozygotes. In particular, umc1907, significantly out of Hardy–Weinberg equilibrium ( p < .05) in all selection cycles (farmer's and breeder's), is located at maize genome bin 3.05, where several genes and QTLs have been identified in previous studies (Mendes‐Moreira et al., ) that might be associated with, or indicating loci controlling, traits consistently changing in both selection approaches. The candidate gene terminal ear1 ( te1 ) (Jackson, ; Schnable & Freeling, ; Vollbrecht & Schmidt, ) and several QTLs controlling days to pollen 2, 7, 12 ( qdpoll2, 7, 12 ) were detected in this region (Lawrence, Seigfried, & Brendel, ).…”

“…() reported 67% and Mendes‐Moreira et al. () reported 80.7%. These high correlations may be associated with loci controlling the cob diameters increase with both selection methods and cycles.…”

Genetic architecture of the maize kernel row number revealed by combining QTL mapping using a high-density genetic map and bulked segregant RNA sequencing

“…QTL mapping is an efficient strategy for exploring the genetic architecture underlying quantitative traits in maize [30, 31]. However, the accuracy and resolution of QTL mapping is significantly affected by the quality and resolution of the genetic map [32].…”