GIGANTEA is required for circadian rhythms in wheat

GIGANTEA (GI) is a plant specific protein that functions in many physiological processes and signalling networks. In Arabidopsis, GI has a central role in circadian oscillators regulating the abundance of ZEITLUPE and TIMING OF CAB1 proteins and is essential for photoperiodic regulation of flowering. We have investigated the structure of the wheat circadian oscillator and how it contributes to yield traits, including heading (flowering). We find that GI is a core component of wheat circadian oscillators that is necessary to maintain robust oscillations in chlorophyll fluorescence and circadian oscillator transcript abundance. Predicted lack of functional GI results in later flowering in wheat in both long days and short days in controlled environment conditions. Our results support and extend previous work which suggests that the pathways by which photoperiodism regulates flowering are not fully conserved between Arabidopsis and wheat. Understanding the molecular basis for photoperiodism in wheat is important for breeders looking to manipulate flowering time and develop new elite, high yielding cultivars.