De novo annotation of the wheat pan-genome reveals complexity and diversity of the hexaploid wheat pan-transcriptome

Abstract

Wheat is the most widely cultivated crop in the world with over 215 million hectares grown annually. However, to meet the demands of a growing global population, breeders face the challenge of increasing wheat production by approximately 60% within the next 40 years. The 10+ Wheat Genomes Project recently sequenced and assembled the genomes of 15 wheat cultivars to develop our understanding of genetic diversity and selection within the pan-genome of wheat. Here, we provide a wheat pan-transcriptome withde novoannotation and differential expression analysis for nine of these wheat cultivars, across multiple different tissues and whole seedlings sampled at dusk/dawn. Analysis of thesede novoannotations facilitated the discovery of genes absent from the Chinese Spring reference, identified genes specific to particular cultivars and defined the core and dispensable genomes. Expression analysis across cultivars and tissues revealed conservation in expression between a large core set of homoeologous genes, but also widespread changes in sub-genome homoeolog expression bias between cultivars. Co-expression network analysis revealed the impact of divergence of sub-genome homoeolog expression and identified tissue-associated cultivar-specific expression profiles. In summary, this work provides both a valuable resource for the wider wheat community and reveals diversity in gene content and expression patterns between global wheat cultivars.