Genome-wide association analysis for lodging tolerance and plant height in a diverse European hexaploid oat collection

Sensitivity to lodging of oat varieties has been reduced in the last decades through the introduction of dwarfing genes. However, lodging may still cause significant yield loss, underscoring the need for new oat varieties with higher levels of lodging tolerance. In the present study, we analysed lodging and plant height in a collection of European oat accessions including landraces, old and modern varieties, in order to perform a genome-wide association study (GWAS) for identifying markers associated to lodging tolerance. This collection has been recently genotyped by the Infinium 6K SNP array for oat and SNP data were analysed as continuous intensity ratios, rather than as discrete genotypes (Tumino et al. 2016, Theor Appl Genet 129, pp. 1711-1724). Phenotypes for lodging severity, plant height and growth habit were collected under natural conditions in eight European countries. Plant height correlated to lodging severity as previously observed in many studies, explaining about 30% of lodging variation. GWAS analyses detected six significant associations for lodging and two for plant height. These results indicate that GWAS can successfully be used for identifying markers associated to lodging in oat, even though lodging is a quantitative trait influenced by several plant characteristics.