A novel transcriptional pathway that controls axillary meristem induction in grasses

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Wheat is an agronomically important food crop worldwide that has evolved through a series of human-driven breeding events over the last ca.10,000 years. Because of this, most modern wheat varieties contain limited genetic variation, commonly referred to as 'genetic bottlenecks'. A trade-off of domestication or repetitive artificial selection was the reduction of secondary shoot outgrowth (branching), resulting in reduced tiller formation in most domesticated wheats compared with their highly-branched wild relatives. Since grains are produced from the tillers, increased tillering is now becoming a sought-after desirable trait to engineer in modern cultivars as it is one way to increase grain yield per hectare. Therefore, understanding how tiller formation occurs is important to ensure greater productivity of our modern food crops. By studying goat grass, a wild wheat relative which produces large albeit variable numbers of tillers per plant, we recently discovered a new molecular pathway that controls secondary branching and thus tiller number, which we named High Tiller Number 1 (HTN1). We also obtained exciting results demonstrating that induction of this pathway is sufficient to increase tiller numbers in modern wheat and rice varieties, suggesting functional conservation of this pathway in the grasses. Based on these exciting new findings, this project aims to elucidate the HTN1 pathway primarily in wheat, for which we have ample experience and unique genomic and genetic resources in hand. Specifically, we will use computational, developmental genetic and molecular approaches to unravel the exact nature of this pathway and uncover the various components and regulatory factors involved, including how the environment (e.g. temperature, nutrient availability) affects the HTN1 pathway.We anticipate that this work will not only help us understand how tiller formation is achieved in wheat but will also provide essential know-how to protect and enhance yield in cereal crops.