Update on the A Genome (Triticum urartu) Structure-Function Analysis

Bread wheat (Triticum aestivum), one of the most widely cultivated and consumed food crops in the world, is a hexaploid containing A, B and D genomes. Due to its complex polyploidy nature and large genome size (17 Gb), the genetic and functional analysis of bread wheat is extremely challenging. Triticum urartu is the progenitor of wheat A genome. It plays a central role in wheat evolution, domestication and genetic improvement because the A genome is the basic genome of bread wheat and other polyploidy wheats. Therefore, we are working on the genome sequencing of T. urartusince 2009.

Two years ago, we have sequenced T. urartu accession G1812 using a whole-genome shotgun strategy on the Illumina HiSequation (2000) platform, and generated a draft genome of wheat A genome (Ling et al., 2013, Nature 496: 87-90). To completely sequence the wheat A genome, we constructed 3 BAC libraries and created BAC contigs using the whole genome profiling technology by collaboration with Keygene, the Netherlands. Based on BAC contig data, we selected more than 45,000 BACs by MTP approach, and sequenced them. The sequence assembly and genome analysis is in progress. For assignment and order of the genome sequences on their corresponding chromosome, we recently also sequenced 480 F2 plants derived from two T. urartuaccessions (G1812 and G3146) using RAD-sequencing technology, and identified more than 400,000 SNPs. With them, a high resolution SNP map has been constructed. 

In conclusion, completing the genome sequence of T. urartuwill provide a diploid reference for the analysis of polyploidy wheat genomes, and is a valuable resource for the genetic improvement of wheat to meet the future challenges of global food security and sustainable agriculture.

This work was supported by The Ministry of Science and Technology of China (grant no. 2010DFB33540) and by The State Key Laboratory of Plant Cell and Chromosome Engineering (grant no. PEEC-201201).