Cloning a Major QTL for Dormancy in Wheat

Increasing grain dormancy in wheat is an important goal for breeders globally in order to reduce the risk of pre-harvest sprouting. However, the identification of dormancy-related genes has been hampered by the complexity of the wheat genome. We present a new pipeline for cloning QTL in wheat that we have used for genetically characterise the major grain dormancy QTL located on chromosome 4AL. Our approach uses a Multi-parent Advanced Generation Inter-Cross (MAGIC) population and a set of multiple, MAGIC-derived, near-isogenic families segregating for the targeted QTL. RNA samples were taken from those families during grain development and pooled together depending on the presence or absence of the QTL. By using RNA-seq and pool-comparisons, we have identified in the QTL region two candidate genes of the same family displaying sequence and expression changes. Functional analysis revealed that those genes are positive regulators of dormancy in wheat. The new gene-based markers identified here will improve the accuracy of the QTL selection in breeding programs.