Plant Productivity and Leaf Starch During Grain Fill Is Linked to QTL Containing Flowering Locus T1 (FT1) in Wheat (Triticum aestivum L.)

Shifts in the environment due to climate change necessitate breeding efforts aimed at adapting wheat to longer, warmer growing seasons. In this study, 21 modern wheat (<i>Triticum aestivum</i> L.) cultivars and 29 landraces were screened for flag leaf starch levels, with the goal of identifying a genetic marker for targeted breeding. The landrace PI 61693 was identified as having exceptionally high flag leaf starch values. Yield trials were carried out in a Berkut × PI 61693 recombinant inbred line (RIL) population and a negative correlation was observed between leaf starch, flowering time, and yield. Genetic mapping identified a Quantitative Trait Loci (QTL) explaining 22-34% variation for leaf starch, flowering time, biomass, and seed yield. The starch synthase <i>TraesCS7D02G117800</i> (<i>wSsI-1</i>) is located in this region, which possibly accounts for leaf starch variation in this population; also within this QTL is <i>TraesCS7D02G111600</i> (<i>FT-D1</i>). Sequencing of <i>FT-D1</i> identified a single base pair deletion in the 3rd exon of the Berkut allele. This indel has recently been shown to significantly impact flowering time and productivity, and likely led to significant variation in flowering date and yield in this population. Here, we illustrate how allelic selection of <i>FT-D1</i> within breeding programs may aid in adapting wheat to changing environments.