Seasonality control of barley flowering: from the lab to the field

Flowering time is a critical developmental transition in barley, as the plant stops making leaves and allocates resources to reproduction. The circadian clock is a key determinant for when in a season barley flowers. The clock gene Ppd-H1 is associated with the spring behaviour and we have identified another clock gene termed EAM8 that further "migrates" barley. In arid conditions such as the Iberian peninsula, it is advantageous for barley to be sown before winter to leverage mild winter conditions, resulting in higher yield and increased fitness. Winter barley is the ancestral genetic state, and germinates in autumn before overwintering, enabling the process of vernalisation to trigger receptiveness for the potential to flower. Flowering then occurs with the advancing photoperiods in the spring.

There is an academic and pre-breeding interest to appraise barley flowering in a genetic context where there are vernalisation requirements, but where the oscillator has been tuned to appropriately time flowering to a given agro-climatic zone. For this the York and Syngenta partners have constructed clock mutations in winter barley. These would be assessed under controlled climate chambers, greenhouse settings and multiple field sites in the UK and around continental Europe for heading date and flowering time. Gene-expression profiles and changes in the reproductive stem-cells (the floral meristem) would be imaged. Coupled to biometry of plant form, including tillering and numerous seed-yield traits, grain characteristics would be assessed and quantified in these lines to additionally relate flowering time in controlled and field setting to products of commercial relevance.

It is of profound academic interest to understand how a plant responds to its growing season. The molecular genetics of the flowering-time network in winter barley is not known, and the clock alleles we generated for this work are advanced genetic states to evaluate this molecular-genetic network.