Miller Magazine Issue: 130 October 2020

28 NEWS MILLER / OCtOber 2020 A team of scientists has completed one of the largest genetic analyses ever done of any agricultural crop to find desirable traits in wheat’s extensive and unexplored diversity. Massive-scale genomic study reveals wheat diversity for crop improvement Researchers working on the Seeds of Discovery (SeeD) initiative, which aims to facilitate the effective use of genetic diversity of maize and wheat, have genetically characterized 79,191 samples of wheat from the germplasm banks of the International Maize and Wheat Improvement Center (CIM- MYT) and the International Center for Agricultural Research in the Dry Areas (ICARDA). The findings of the study published in Nature Communicati- ons are described as “a massive-scale genotyping and diversity analysis” of the two types of wheat grown globally — bread and pasta wheat — and of 27 known wild species. Wheat is the most widely grown crop globally, with an annu- al production exceeding 600 million tons. Approximately 95% of the grain produced corresponds to bread wheat and the re- maining 5% to durum or pasta wheat. The main objective of the study was to characterize the ge- netic diversity of CIMMYT and ICARDA’s internationally avai- lable collections, which are considered the largest in the world. The researchers aimed to understand this diversity by mapping genetic variants to identify useful genes for wheat breeding. FROM GERMPLASM BANK TO BREADBASKET The results show distinct biological groupings within bread wheats and suggest that a large proportion of the genetic di- versity present in landraces has not been used to develop new high-yielding, resilient and nutritious varieties. “The analysis of the bread wheat accessions reveals that re- latively little of the diversity available in the landraces has been used in modern breeding, and this offers an opportunity to find untapped valuable variation for the development of new varie- ties from these landraces”, said Carolina Sansaloni, high-throu- ghput genotyping and sequencing specialist at CIMMYT, who led the research team. The study also found that the genetic diversity of pasta wheat is better represented in the modern varieties, with the exception of a subgroup of samples from Ethiopia. The rese- archers mapped the genomic data obtained from the genoty- ping of the wheat samples to pinpoint the physical and genetic positions of molecular markers associated with characteristics that are present in both types of wheat and in the crop’s wild relatives. According to Sansaloni, on average, 72% of the markers ob- tained are uniquely placed on three molecular reference maps and around half of these are in interesting regions with genes that control specific characteristics of value to breeders, farmers and consumers, such as heat and drought tolerance, yield po- tential and protein content. The data, analysis and visualization tools of the study are fre- ely available to the scientific community for advancing wheat research and breeding worldwide. “These resources should be useful in gene discovery, clo- ning, marker development, genomic prediction or selection, marker-assisted selection, genome wide association studies and other applications,” Sansaloni said.