Genome-wide circadian gating of a cold temperature response in bread wheat

Abstract

Circadian rhythms coordinate the responses of organisms to their daily fluctuating environments, by establishing a temporal program of gene expression. This schedules aspects of metabolism, physiology, development and behaviour according to the time of day. Circadian regulation in plants is extremely pervasive, and is important because it underpins both productivity and seasonal reproduction. Circadian regulation extends to the control of environmental responses through a regulatory process known as circadian gating. Circadian gating is the process whereby the circadian clock regulates the response to an environmental cue, such that the magnitude of response to an identical cue varies according to the time of day of the cue. Here, we show that there is genome-wide circadian gating of responses to cold temperatures in plants. By using bread wheat as an experimental model, we establish that circadian gating is crucial to the programs of gene expression that underlie the environmental responses of a crop of major socioeconomic importance. Furthermore, we identify that circadian gating of cold temperature responses are distributed unevenly across the three wheat subgenomes, which might reflect the geographical origins of the ancestors of modern wheat.

The interplay between the circadian clock and abiotic stress responses mediated by ABF3 and CCA1/LHY

“…Among CCA1 and LHY targets, evening-expressed genes are highly enriched, and many of them contain EE motifs; however, CCA1 and LHY can also target morning-expressed genes or arrhythmic genes ( 45 ) ABF3 , featuring an oscillating pattern with a peak in the morning, falls in the category of CCA1/LHY targeted morning-expressed genes. Circadian clock can gate cold responses in Arabidopsis and bread wheat ( 41 , 54 ), specifically low-temperature induction of CBF1, 2, and 3 is gated by the circadian clock in Arabidopsis ( 54 ). Here, we demonstrate that the stress-induction of ABF3 differs at ZT1 and ZT10, suggesting the circadian clock may gate the stress responsiveness of ABF3 .…”

“…Studies in crops also revealed the important role of the circadian clock in regulating stress responses. The circadian clock can gate genome-wide cold responses in bread wheat ( 41 ). PRR homologous gene Ppd-H1 in barley integrates drought stress signals to modulate spike development and flowering time ( 42 ).…”