Manipulation of meristem initiation and maintenance in wheat and rice

The grasses are one of the largest and most diverse families within the angiosperms and make up to 70% of all crops grown. Domestication of wild ancestors of the major cereals involved artificial selection of agronomically important traits like tillering. Plant architecture in the grasses is influenced by the initiation and outgrowth of axillary meristems that determine the number of reproductive organs formed. Inflorescence architecture has also been a major selection trait in human domestication of cereal crops and is determined by a complex genetic network of meristematic transcription factors. The RWP-RK transcription factors are a family of developmental regulators that are tightly expressed in reproductive tissue and are implicated in early embryogenesis across the plant kingdom. We’ve found that ectopic expression of zygotic the RWP-RK genes TaRKD1-7D and OsRKD3 leads to increased tiller number, inflorescence size and seed weight in wheat and rice respectively. Interestingly, we also see greater increases of these traits in conditions of lower nitrogen availability. Through extensive bioinformatics analysis we hypothesise that ectopic expression of these transcription factors upregulates pluripotency factors, specifically cell cycle regulators, histones, histone methylation factors and meristem determinacy genes like trehalose phosphate synthases. This increases meristem formation and indeterminacy by creating and maintaining stem cell niches that determine plant architecture. This is a novel strategy for manipulating yield determining traits across a range of cultivars and cereal crop species