Researchers have recently assembled a homoeolog-resolved reference genome of decaploid Thinopyrum ponticum, an important wild relative of wheat.

The study, published in Molecular Plant, was led by HE Fei from the Institute of Genetics and Developmental Biology (IGDB) of the Chinese Academy of Sciences (CAS), who also serves as group leader at the CAS-JIC Centre of Excellence for Plant and Microbial Science (CEPAMS), in collaboration with JI Wanquan's group at Northwest A&F University and other researchers.

The study provides a high-quality 41.33-Gb genome assembly for this highly complex decaploid species, which contains 70 chromosomes. The researchers found extensive homoeologous exchanges and recombination among chromosome groups, revealing that the genome has a segmental allopolyploid organization. These findings provide new insights into the evolution and stabilization of highly polyploid plant genomes.

Thinopyrum ponticum has long been valued as a genetic resource for wheat improvement because of its resistance to disease and tolerance to environmental stresses, including salinity, drought and poor soils.

The new genome contains more than 577,000 high-confidence genes, including an expanded cluster of the Fusarium head blight resistance gene Fhb7. The researchers also analysed 348 wheat–Th. ponticum introgression lines, enabling more precise identification of chromosome segments introduced from Th. ponticum and useful genetic variation for wheat breeding.

The study also builds on a long history of wheat genetics research at IGDB. Beginning in the 1950s, CAS geneticist LI Zhensheng pioneered distant hybridization between wheat and Thinopyrum ponticum, leading to the development of the well-known "Xiaoyan" wheat germplasm and varieties. LI is also a co-author of the present study, while JI, one of the senior researchers involved in the work, was trained by LI.

The new genome therefore brings a classical genetic resource that has been studied for decades into the era of high-resolution genomics. By combining wheat distant-hybridization resources and cytogenetics with modern long-read sequencing, polyploid genome assembly and comparative genomics, the work highlights the value of long-term collaboration.

According to the researchers, the resulting genome provides an important platform for studying polyploid evolution, identifying genes associated with stress resilience, and accelerating the use of wild-relative diversity in wheat improvement.