Identification of Elite Agronomic Traits Using Chromosome Arm Substitution Lines of <i>Triticum dicoccoides</i> in the Background of Common Wheat

To effectively mine and utilize the valuable genes of wild emmer wheat (<i>Triticum dicoccoides</i>, 2n = 4x = 28, AABB), this study conducted an investigation of agronomic traits using two sets of chromosome arm substitution lines (CASLs) of wild emmer wheat in the backgrounds of the common wheat varieties Bethlehem (BLH) and Chinese Spring (CS). The results indicated significant differences in growth parameters, including seedling agronomic traits, heading date (HD), and yield traits among the various CASLs in both the BLH and CS backgrounds. In both genetic backgrounds, the number of tillers in CASL7BS was significantly fewer than that of the parents. Additionally, the average leaf width of six CASLs (2BS, 1AL, 7AL, 5BS, 4AS, and 2BL) was significantly narrower compared to the parents. Among CASLs in the CS background, CASL2BS exhibited a significantly narrower average leaf width and shorter average plant height compared to both the parents and early-maturing CASLs. Conversely, CASL4AL exhibited significantly more tillers and a shorter average plant height than the other CASLs. In the BLH background, the spike phenotypes of all CASLs showed no significant differences from BLH. However, in the CS background, CASL6AS and CASL5AL demonstrated significantly longer spike lengths than CS. Moreover, CASL6BL had more spikelets per spike than CS. CASLs 4AS, 4AL, 6BS, and 6BL exhibited basal short awns and apical long awns, whereas the remaining CASLs displayed no awns, a pattern consistent with CS. We hypothesize that genes governing physiological traits such as seedling tiller number, leaf width, plant height, and spike traits are likely located on the corresponding chromosome arms.