Breeding Potential of European Flint Maize Landraces Evaluated by their Testcross Performance

Abstract

A plethora of maize (Zea mays L.) landraces is stored in gene banks worldwide. However, information about their value in breeding is scarce and strategies for identifying the most promising landraces in prebreeding are largely lacking. This study was conducted to (i) evaluate the testcross performance of 70 European flint landraces in combination with two elite dent testers and compare these results with the performance of modern hybrids for important agronomic traits, (ii) estimate the genetic variances among landraces and trait correlations for these two testcross series as well as the correlation between them, and (iii) devise a testing scheme for assessing the breeding potential of a large number of landraces for hybrid breeding. Grain yield of the landrace testcrosses was on average about 26% lower than modern hybrids. Genotypic variances among landrace testcrosses were significant for all traits, and genetic correlations were moderate to high for most trait combinations in both testcross series. Thus, it seems promising to tap this huge genetic reserve for enlarging the genetic base of the elite flint germplasm pool in Central Europe. Since the genetic correlation between the two testcross series exceeded 0.74 for all traits, we recommend assessing the breeding potential of landraces for broadening existing heterotic groups by evaluating their testcross performance in combination with one or two elite single‐cross tester(s) from the opposite heterotic pool. Subsequently, doubled haploid lines from a few of the most promising landraces could be produced to exploit the large genetic variation within landraces to the full extent.

Genomic Prediction Within and Among Doubled-Haploid Libraries from Maize Landraces

“…Nevertheless, DH production from landraces is still laborious and expensive, and the success rate is unpredictable . Therefore, it is crucial to screen a large number of accessions for their agronomic performance in line per se and testcross trials (Böhm et al 2014(Böhm et al , 2017, and test their suitability for DH production before embarking on the production of DHL from landraces and the application of GP.…”

“…In allogamous crops, mining the genetic diversity of seed bank accessions entails two challenges. First, one must identify the most promising accessions, commonly based on passport data provided by seed banks and results from field trials, in which the landraces are evaluated for their per se performance and/or testcross performance with suitable testers (Salhuana and Pollak 2006;Böhm et al 2014). Selection among accessions is not sufficient because both molecular and phenotypic data from various crops suggest that more genetic variation lies within than between landraces (Greene et al 2014;Monteiro et al 2016;Böhm et al 2017;Mayer et al 2017).…”

Selective loss of diversity in doubled-haploid lines from European maize landraces

“…Doubled-haploid lines show particularly poor fitness compared to outcrossing lines and even compared to inbred lines (Strigens et al 2013;Böhm et al 2014). The observed inbreeding depression in DH and inbred lines in maize is likely due to accumulation of deleterious alleles as a result of inbreeding (Bataillon and Kirkpatrick 2000;Charlesworth and Willis 2009).…”

Breeding potential of maize landraces evaluated by their testcross performance

“…These programs may represent development of new pools for breeding as well as identification of new heterotic patterns in maize (Nass, Paterniani, 2000;Shimelis, Laing, 2012). However, a few such programmes are a limiting factor for more extensive utilisation of landraces from gene bank collections, where many of them were collected before disappearing from practical cultivation in foresight of their value for future generations (Böhm et al, 2015).…”

“…There is a huge yet unexploited genetic diversity in maize landraces as a product of thousands years of evolution under domestication and hybridization. Considering the genetic variation within the flint landraces, it seems promising to use the best of them for introgression programs to enlarge the genetic base of the elite flint germplasm pool in Central Europe (Böhm et al, 2015). Landraces adapted to local growth conditions could play significant role in this process and, according to Mikić et al (2017), even the smallest participation of local germplasm can have a great impact on the final result.…”