Association mapping of traits relevant to fitness of barley in the future climate

Cathrine Heinz Ingvordsen¹, Gunter Backes², Michael F. Lyngkjær³, Teis N. Mikkelsen¹, Marja Jalli⁴, Pirjo Peltonen-Sainio⁴, Rikke Bagger Jørgensen¹

¹ DTU, KT, Roskilde, Denmark, ²Kassel University, Witzenhausen, Germany, ³ University of Copenhagen, SCIENCE, Denmark,  ⁴MTT, Jokioinen, Finland, cahi@kt.dtu.dk

Climate is changing and challenging crop production. Our results indicate a 30 % decrease in overall yield of 138 spring barley accessions cultivated in a climate phytotron under future climate conditions, but also considerable differences between the individual accessions. To secure the future production, accessions producing stable and high yields must be identified for use in breeding programs. In the experiment 138 spring barley accessions were exposed to a +5°C temperature increase (24/17°C day/night), an elevated carbon dioxide concentration at 700 ppm, and elevated ozone at 100-150 ppb in single or two factor treatments. All treatments and accessions received the same amount of water. The production parameters grain weight, aboveground vegetative biomass, total number of ears and ears with grain were obtained on single plant basis, and grain number as well as harvest index were calculated. The stability indices, Wricke’s ecovalence and environmental variance were calculated for each production parameter over all treatments. For genome-wide association analysis DNA from the barley accessions was applied on an array of 7864 SNP markers (ILLUMINA).

A total of 66 traits from the 5 different environmental treatments were included in the genome-wide association mapping. After strict validation to exclude false positives 118 SNP markers were found to associate with the phenotypic differences at logP-values ranging from 2.96 to 6.69. Of those markers 44 were annotated to a chromosome. Of the 118 associated markers 34 associated with more than one of the traits. For 11 of the 34 markers associated with more than one trait, either of the stability indices could be found. Seven markers associated with one of the climate stability indices for grain weight (logP values 3.27-4.92).

Stable and high yielding cultivars are essential to secure production under future climate conditions. Despite the challenges in establishment of markers for quantitative traits, our findings with identification of markers associated with stability and grain yield, suggest that genome-wide association mapping is a valuable tool, when searching for fitness in the future environment.