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One of the most important applications of genomic selection in maize breeding is to predict and identify the best untested lines from biparental populations, when the training and validation sets are derived from the same cross. Nineteen tropical maize biparental populations evaluated in multienvironment trials were used in this study to assess prediction accuracy of different quantitative traits using low-density (-2 0 0 markers) and genotyping-by-sequencing (GBS) single-nucleotide polymorphisms (SNPs), respectively. An extension of the Genomic Best Linear Unbiased Predictor that incorporates genotypexenvironment (GE) interaction was used to predict genotypic values; cross-validation methods were applied to quantify prediction accuracy. Our results showed that: (1) low-density SNPs (-2 0 0 markers) were largely sufficient to get good prediction in biparental maize populations for simple traits with moderate-to-high heritability, but GBS outperformed low-density SNPs for complex traits and simple traits evaluated under stress conditions with low-to-moderate heritability; (2) heritability and genetic architecture of target traits affected prediction performance, prediction accuracy of complex traits (grain yield) were consistently lower than those of simple traits (anthesis date and plant height) and prediction accuracy under stress conditions was consistently lower and more variable than under well-watered conditions for all the target traits because of their poor heritability under stress conditions; and (3) the prediction accuracy of GE models was found to be superior to that of non-GE models for complex traits and marginal for simple traits. [ABSTRACT FROM AUTHOR]

With 6 figures and 3 tables Anther extrusion (AE) has been suggested as one of the resistance mechanisms to Fusarium head blight (FHB) in wheat, but not well investigated. The objectives of this study were to assess AE in the double haploid population ‘Arina’ × ’NK93604’, evaluate its relationship both with FHB and deoxynivalenol (DON) accumulation, and map quantitative trait loci (QTLs). AE was studied in 2005−2007 and its relationship to FHB and DON content was analysed with data from Fusarium culmorum inoculations in 2001–2003 and with Fusarium graminearum in 2007. AE showed continuous distribution, transgressive segregation, minimal genotype × year interactions and was highly heritable ( H2 = 0.91). Mean AE showed highly significant negative correlations both with FHB ( r = −0.53 to −0.69, P = 0.0001) and DON ( r = −0.39 to −0.46, P = 0.0001). Composite interval mapping identified 4 QTLs for mean AE over 2 years that explained 53.6% of the total phenotypic variation. The phenotypic variance explained by the QTLs on chromosomes 1AL, 1BL, 4DL and 6AS varied from 7.4% to 18.3%. This is the first report describing QTLs for AE and to look systematically for association of AE with FHB and DON. [ABSTRACT FROM AUTHOR]