Abstract
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 CAB EXPRESSION 1 proteins and is essential for photoperiodic regulation of flowering. We have investigated how ortholgues of this component of Arabidopsis circadian oscillators contributes to circadian rhythms and yield traits, including heading (flowering) in wheat. 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.
Highlight GIGANTEA is required for robust circadian oscillations in wheat and regulates heading, most likely through a PHOTOPERIOD-1-dependent pathway.
Competing Interest Statement
Mathew Hannah is an employee of BASF. The authors declare no other competing interests
Footnotes
Contact: Laura Taylor: laurataylor1994.lt{at}gmail.com, Gareth Steed: gareth_steed{at}hotmail.co.uk, Gabriela Pingarron-Cardenas: gp519{at}cam.ac.uk, Lukas Wittern: lukaswittern{at}gmail.com
Figure 4 and associated text updated to reflect correction to error in statistical analysis for the data described in this figure; Textual changes to improve clarity in analysis of results and discussion; Supplementary information added describing the environmental conditions during field trials; Expanded analysis of circadian parameters included in revised version; Figure legends have been amended to increase clarity of description; Typographical errors corrected; Added new data and figure showing effect of mutations on GI transcript abundance; Title modified to reflect the more nuanced interpretation of the data.
Abbreviations
- CF
- Chlorophyll fluorescence
- CCA1
- CIRCADIAN CLOCK ASSOCIATED 1
- CO
- CONSTANS
- LL
- Continuous light
- FKF1
- FLAVIN BINDING KELCH REPEAT 1
- FT
- FLOWERING LOCUS T
- GI
- GIGANTEA
- GS55
- Growth stage 55
- LD
- Light dark
- LHY
- LONG ELONGATED HYPOCOTYL
- NIAB
- National Institute of Agricultural Botany
- NPQ
- Non-photochemical quenching
- PPD-1
- Photoperiod 1
- PRR
- PSEUDO RESPONSE REGULATOR
- RAE
- Relative Amplitud Error
- TOC1
- TIMING OF CAB EXPRESSION 1
- WT segregant
- Wild type
- ZTL
- ZEITLUPE