Genome-wide association analysis of root system architecture features and agronomic traits in durum wheat

Root system architecture (RSA) has positive effects on wheat growth and its yield performance. As root features are difficult to manipulate through conventional breeding strategies, marker-trait association (MTA) could be helpful for the improvement of RSA. In the present study, 112 durum wheat genotypes were investigated for several root system features as well as some agronomic traits. The population was genotyped using a 15K SNP and a total of 3321 markers were used in the association analysis. A total of 581 significant marker-trait associations were identified in all of the 14 chromosomes. The percentages of phenotypic variation (R²) of measured traits varied between 8.76 and 24.81%. Out of 581 associated markers, 125 loci were linked with multiple traits. The most significant associations on measured traits were detected for genome B compared to genome A (61% vs 39%). Also, major associated loci existed on chromosomes 1A, 1B, 2B, 3B, and 5B, which could be considered in the future breeding programs to manipulate relevant traits using marker-assisted selection procedures. Among associated SNP markers, most markers were related to the number of days to spike heading (181), anthesis (53), booting (69), physiological maturity (41), water use efficiency (109), and transpiration efficiency (24). Furthermore, the large number of QTLs (167 in total) for RSA and agronomic traits were detected. The highest numbers of QTLs were related to WUE (23), DAS (23), DB (21), and DA (20) than other traits. Among the detected QTLs, 16 QTLs for RSA overlapped with different agronomic traits, as well as 6 QTLs co-located with other RSA traits in at last one trait. These results are helpful for better understanding the genetic basis of root system features and agronomic traits. Furthermore, these results could be valuable for facilitating pyramiding of the ideal alleles using the MAS approach for favorable plant-type and high water use efficiency in the future durum wheat breeding programs.