An updated protocol for accelerating winter wheat genetic improvement by integrating doubled haploid and off-season breeding technologies

Accelerating winter wheat breeding is vital for addressing the global food crisis arising from population growth and climate change. Doubled haploid (DH) technology can produce stable inbred lines within two generations, thereby shortening breeding cycles. However, its application in winter wheat breeding is constrained by low haploid induction and chromosome doubling rates, and inefficient evaluation of agronomic traits. Germinating-seed vernalization eliminates the need for seedling transplantation, enabling cost-effective, high-throughput off-season trials and seed multiplication. To improve breeding efficiency, we optimized haploid induction and chromosome doubling, and established an enhanced winter wheat DH evaluation system under seasonal and off-season conditions. Using maize hybrid Jingketian 608 or cogongrass ( Imperata cylindrica (L.) P. Beauv.) as the pollen donors and propyzamide as the chromosome doubling agent, we achieved a haploid induction rate of 48.4% and a doubling rate of 92.6%. Shifting induction from F 1 to F 2 generation boosts genetic gain, as superior plants in segregating populations can be selected for DH production. Combining population development based on genomic and phenotypic data, marker-assisted selection and DH technology with germinating-seed vernalization enables the development of elite wheat varieties within three years, substantially accelerating winter wheat breeding progress and safeguarding food security.