Premium
QTL Mapping in Testcrosses of European Flint Lines of Maize: II. Comparison of Different Testers for Forage Quality Traits
Author(s) -
Lübberstedt Thomas,
Melchinger Albrecht E.,
Klein Dietrich,
Degenhardt Heinz,
Paul Christian
Publication year - 1997
Publication title -
crop science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.76
H-Index - 147
eISSN - 1435-0653
pISSN - 0011-183X
DOI - 10.2135/cropsci1997.0011183x003700060041x
Subject(s) - quantitative trait locus , biology , forage , inbred strain , selfing , epistasis , agronomy , gene–environment interaction , trait , genotype , genetics , population , gene , demography , sociology , computer science , programming language
Improving forage quality is a major goal in maize breeding for cooler climates. In this study, we mapped and characterized quantitative trait loci (QTL) affecting testcross (TC) performance of important forage maize quality traits and investigated their consistency across testers. Two elite flint inbred lines were crossed to generale 380 F 2 individuals, 345 of which were genotyped at 89 RFLP marker loci. The 380 F 3 lines produced by selfing the F 2 individuals were testcrossed to two dent inbred testers. Each TC series was evaluated in field trials with two replications in five environments. The following six traits were analyzed: in vitro digestible organic matter (IVDOM), acid detergent fiber (ADF), metabolizable energy concentration (MEC), and protein concentration (CPC), all determined by near infra‐red reflectance spectroscopy (NIRS), as well as metabolizable energy yield (MEY) and protein yield (CPY). Genotypic variances (σ̂ 2 g ) mostly significant for these traits in both TC series. Heritabilities ranged from 0.24 to 0.69 and were low for IVDOM, ADF, and MEC. Genotypic correlations between testers exceeded 0.64 for each trait. Between four (CPY) and ten (CPC) QTL were detected in each TC experiment by composite interval mapping, explaining between 48.4% and 85.3% of σ̂ 2 g in a simultaneous fit. QTL results were consistent across testers for CPC and CPY, but not for IVDOM, ADF, MEC, and MEY. Few of the detected QTL displayed significant digenic epistatic interactions. The digestibility traits IVDOM, ADF, and MEC were tightly correlated (|r̂ g | > 0.88) with each other and displayed intermediate genotypic correlations (r̂ g ) with plant height and starch concentration, but low r̂ g values with dry matter yield or dry matter concentration. In most cases, the magnitude of r̂ g corresponded well with the number of common QTL regions affecting both traits.