Email: m.bogard@arvalis.fr

Phosphorus (P) is a macronutrient involved in key metabolic activities and structures in plants (photosynthesis, cell membrane, energy, and nucleic acid synthesis). The world phosphorus resources, contained in phosphate rocks, are being exhausted. Therefore, breeding for tolerant varieties to phosphorus deficiency is becoming a target to maintain sustainable cropping systems.

The objective of this study was to identify genetic factors determining tolerance to P deficiency in bread wheat using a genome-wide association study (GWAS) approach. A panel of 199 winter bread wheat (Triticum aestivum) varieties released between 1988 and 2022 mainly in France and in the United-Kingdom was used. The panel was genotyped using SNP markers from the TaBW280K, the 90K iSelect and the 35K breeder arrays.

This panel was tested in three trials in France in 2021 and 2022 under optimal and low soil P concentrations. Different traits were measured such as grain yield (GY) and its components, earliness, plant height, grain P concentration and P use efficiency (PUE) and tolerance indices were calculated. The heritability of PUE ranged from 0.23 to 0.59 and interactions between genotypes and environments were observed. Out of the 201,557 SNPs used for the GWAS, 120 were found significantly associated to PUE related traits above the LOD threshold of 6.05. Based on linkage disequilibrium, we identified 18 quantitative trait loci (QTL) on 10 chromosomes (2A, 2B, 2D, 3A, 4B, 4D, 5A, 5B, 6B and 7B) for traits related to PUE.

Some of the QTL found in this study colocalized with known genes such as Ppd-D1 and Phosphate starvation response. A genomic prediction model for PUE was calibrated and showed moderate predictive ability after cross-validation (r = 0.47). Markers and genomic prediction models obtained in this study could be useful in breeding for PUE in the early stage of a breeding program.