Email: sanazulfiqar3103@gmail.com

With global population growth and declining cropland availability, enhancing wheat productivity is critical for food security. Strategic trait-based improvements emerge as a sustainable approach in wheat breeding. Mutation breeding, particularly through physical mutagens such as γ-rays, offers an economically viable strategy for creating novel genetic resources capable of combating a wide spectrum of biotic and abiotic stresses.

We employed the high throughput DArTseq™ technology to assess the genetic diversity and functional annotation of 33 newly developed wheat mutant lines compared to their wild type. A total of 157,608 presence-absence variants (PAVs) were identified distributed across all wheat sub-genomes. The maximum number of PAVs were detected on Chr 7D (2877) followed by Chr 7B (2711), Chr 2B (2658), and Chr 3B (2622). Across mutant lines, the largest number of variants were identified in mutant line Pb-M-2061 (23,643) and Pb-M-59 (22,381). Hierarchical clustering was performed, and mutant lines were grouped into three main clusters.

Furthermore, out of 7,910 PAVs consistently identified over replicates, 3,252 were those that were present in mutant lines but were absent in the wild type. Among these, 1,480 were found in mutant line Pb-M-1027 and 656 in line Pb-M-1323. These PAVs were further characterized within the wheat transcriptome. Out of the 3,252 PAVs specific to mutants, 1,238 were found in the wheat transcriptome that contained 152 characterized and 1,196 uncharacterized genes.

Clusters of orthologous genes (COGs) and Gene ontology (GO) terms associated with PAV-containing genes were identified that showed involvement in various pathways, including disease resistance, cellular processes, signaling, storage and metabolism. Mutant lines Pb-M-1027, Pb-M-2302, and Pb-M-1323 exhibited a diverse array of beneficial traits including disease resistance, increased grain yield, drought tolerance, heat tolerance, larger grain size, improved photosynthetic efficiency, high harvest index, cold tolerance, and high chlorophyll content.

Other lines, including Pb-M-1575, Pb-M-1946, Pb-M-196, Pb-M-2517, Pb-M-2260, and Pb-M-1530, also displayed a wide range of valuable traits. Some traits were specific to certain mutant lines, including disease resistance to a specific disease, grain characteristics, and environmental stress tolerance.

Many traits were shared among multiple mutant lines, indicating the potential for incorporating these traits into breeding programs. These findings provide valuable insights into the genetic diversity, functional annotation, and trait associations of wheat mutant lines, offering significant potential for wheat improvement.