Simultaneous improvement of grain yield and grain protein concentration in durum wheat by using association tests and weighted GBLUP

Key message Simultaneous improvement for GY and GPC by using GWAS and GBLUP suggested a signifcantapplication in durum wheat breeding.Abstract Despite the importance of grain protein concentration (GPC) in determining wheat quality, its negative correlationwith grain yield (GY) is still one of the major challenges for breeders. Here, a durum wheat panel of 200 genotypes wasevaluated for GY, GPC, and their derived indices (GPD and GYD), under eight diferent agronomic conditions. The plantmaterial was genotyped with the Illumina 25 k iSelect array, and a genome-wide association study was performed. Two statistical models revealed dozens of marker-trait associations (MTAs), each explaining up to 30%. phenotypic variance. Twomarkers on chromosomes 2A and 6B were consistently identifed by both models and were found to be signifcantly associated with GY and GPC. MTAs identifed for phenological traits co-mapped to well-known genes (i.e., Ppd-1, Vrn-1). Thesignifcance values (p-values) that measure the strength of the association of each single nucleotide polymorphism markerwith the target traits were used to perform genomic prediction by using a weighted genomic best linear unbiased predictionmodel. The trained models were ultimately used to predict the agronomic performances of an independent durum wheatpanel, confrming the utility of genomic prediction, although environmental conditions and genetic backgrounds may stillbe a challenge to overcome. The results generated through our study confrmed the utility of GPD and GYD to mitigate theinverse GY and GPC relationship in wheat, provided novel markers for marker-assisted selection and opened new ways todevelop cultivars through genomic prediction approaches.