Co-expression Network Analysis of Diverse Wheat Landraces Reveals Marker of Early Thermotolerance and Candidate Master-regulator of Thermotolerance Genes.

Bread wheat (Triticum aestivum L.) is a crop, relied on by billions of people around the world as a major source of both income and calories. Rising global temperatures, however, pose a genuine threat to the livelihood of these people, as wheat growth and yields are extremely vulnerable to damage by heat stress. Here we present the YoGI wheat landrace panel, comprised of 342 accessions which show remarkable phenotypic and genetic diversity thanks to their adaptation to different climates. We quantified the abundance of 110,790 transcripts from the panel and used these data to conduct weighted co-expression network analysis and identify hub genes in modules associated with abiotic stress tolerance. We found that the expression of three hub genes, all heat shock proteins (HSPs), were significantly correlated with early thermotolerance in a validation panel of landraces. These hub genes belonged to the same module, with one (TraesCS4D01G207500.1) likely regulating the expression of the other two hub genes, as well as a suite of other HSPs and heat stress transcription factors (Hsfs). In this work, therefore, we identify three validated hub genes, whose expression can serve as markers of thermotolerance during early development, and suggest that TraesCS4D01G207500.1 is a potential master regulator of HSP and Hsf expression - presenting the YoGI landrace panel as an invaluable tool for breeders wishing to determine and introduce novel alleles into modern varieties, for the production of climate-resilient crops.