Breeding Soft Durum Wheat through Introgression of the T5AL·5VS Translocated Chromosome

The limited culinary utilizations of durum wheat (Triticum turgidum ssp. durum) are partly related to its very hard kernel texture, which is due to the softness genes Puroindoline a (Pina) and Puroindoline b (Pinb) on the Hardness (Ha) locus eliminated during allopolyploid formation. A previous study has reported that the softness genes Dina/Dinb, homologous to Pina/Pinb, were located on the chromosome arm 5VS of wild species Dasypyrum villosum. In the present study, we describe the process of transferring the soft grain texture from D. villosum into durum wheat through homoeologous recombination to develop a Robertsonian translocation. A durum wheat–D. villosum T5AL·5V#5S translocation line, S1286, was developed and characterized by molecular cytogenetic analysis from BC4F2 progeny of durum cv. ZY1286/D. villosum 01I140. The translocation line S1286 exhibited a soft grain texture as evidenced by observation through an electron microscope and a Single Kernel Characterization System (SKCS) hardness value of 5.5. Additionally, a newly developed 5VS/5AS co-dominant InDel marker, LW5VS-1, facilitated the transfer of the T5AL·5V#5S translocated chromosome into diverse durum wheat backgrounds. Subsequently, the T5AL·5V#5S translocated chromosome was transferred into five high-yielding durum wheat backgrounds by backcrossing and traced using marker LW5VS-1. Compared with each recurrent parent, T5AL·5V#5S lines showed good viability, similar development, and no yield penalty. Meanwhile, a significant decrease in plant height of about 6.0% was observed when comparing T5AL·5V#5S translocation lines with their recurrent parents. Accordingly, our results provide an efficient strategy for developing soft kernel durum wheat through the combination of T5AL·5V#5S translocation and the co-dominant marker LW5VS-1, which will be crucial for meeting the future challenges of sustainable agriculture and food security.