Diurnal regulation of alternative splicing associated with thermotolerance in rice by two glycine-rich RNA-binding proteins.

Rice (Oryza sativa L.) production is threatened by global warming associated with extreme high temperatures, and rice heat sensitivity is differed when stress occurs between daytime and nighttime. However, the underlying molecular mechanism are largely unknown.

A competition-attenuation mechanism modulates thermoresponsive growth at warm temperatures in plants.

Global warming has profound impact on growth and development, and plants constantly adjust their internal circadian clock to cope with external environment. However, how clock-associated genes fine-tune thermoresponsive growth in plants is little understood. We found that loss-of-function mutation of REVEILLE5 (RVE5) reduces the expression of circadian gene EARLY FLOWERING 4 (ELF4) in Arabidopsis, and confers accelerated hypocotyl growth under warm-temperature conditions.

REVEILLE 7 inhibits the expression of the circadian clock gene EARLY FLOWERING 4 to fine-tune hypocotyl growth in response to warm temperatures.

The circadian clock maintains the daily rhythms of plant growth and anticipates predictable ambient temperature cycles. The evening complex (EC), comprising EARLY FLOWERING 3 (ELF3), ELF4, and LUX ARRHYTHMO, plays an essential role in suppressing thermoresponsive hypocotyl growth by negatively regulating PHYTOCHROME INTERACTING FACTOR 4 (PIF4) activity and its downstream targets in Arabidopsis thaliana. However, how EC activity is attenuated by warm temperatures remains unclear.

Measuring Hypocotyl Length in Arabidopsis.

Circadian clocks allow organisms to synchronize growth to occur at the most optimal time of the day. In plants, the circadian clock controls the timing of hypocotyl (seedling stem) elongation. The activity of the circadian clock subsequently results in hypocotyl elongation being restricted to a small window around dawn and the early morning.

Timing to grow: roles of clock in thermomorphogenesis.

Plants coordinate their growth and developmental programs with changes in temperature. This process is termed thermomorphogenesis. The underlying molecular mechanisms have begun to emerge in these nonstressful responses to adjustments in prevailing temperature.

The E3 ligase XBAT35 mediates thermoresponsive hypocotyl growth by targeting ELF3 for degradation in Arabidopsis.

Plants are capable of coordination of their growth and development with ambient temperatures. EARLY FLOWERING3 (ELF3), an essential component of the plant circadian clock, is also involved in ambient temperature sensing, as well as in inhibiting the expression and protein activity of the thermoresponsive regulator phytochrome interacting factor 4 (PIF4). The ELF3 activity is subjected to attenuation in response to warm temperature; however, how the protein level of ELF3 is regulated at warm temperature remains less understood.

XBAT31 regulates thermoresponsive hypocotyl growth through mediating degradation of the thermosensor ELF3 in .

Elevated ambient temperature has wide effects on plant growth and development. ELF3, a proposed thermosensor, negatively regulates protein activity of the growth-promoting factor PIF4, and such an inhibitory effect is subjected to attenuation at warm temperature. However, how ELF3 stability is regulated at warm temperature remains enigmatic.

Photoperiod sensing of the circadian clock is controlled by EARLY FLOWERING 3 and GIGANTEA.

ELF3 and GI are two important components of the Arabidopsis circadian clock. They are not only essential for the oscillator function but are also pivotal in mediating light inputs to the oscillator. Lack of either results in a defective oscillator causing severely compromised output pathways, such as photoperiodic flowering and hypocotyl elongation.

The DET1-COP1-HY5 pathway constitutes a multipurpose signaling module regulating plant photomorphogenesis and thermomorphogenesis.

Developmental plasticity enables plants to respond to elevated ambient temperatures by adapting their shoot architecture. On the cellular level, the basic-helix-loop-helix (bHLH) transcription factor phytochrome interacting factor 4 (PIF4) coordinates this response by activating hormonal modules that in turn regulate growth. In addition to an unknown temperature-sensing mechanism, it is currently not understood how temperature regulates PIF4 activity.

Natural variation reveals that intracellular distribution of ELF3 protein is associated with function in the circadian clock.

Natural selection of variants within the Arabidopsis thaliana circadian clock can be attributed to adaptation to varying environments. To define a basis for such variation, we examined clock speed in a reporter-modified Bay-0 x Shakdara recombinant inbred line and localized heritable variation. Extensive variation led us to identify EARLY FLOWERING3 (ELF3) as a major quantitative trait locus (QTL).

An overview of natural variation studies in the Arabidopsis thaliana circadian clock.

Circadian clocks are ubiquitous mechanisms that provide an adaptive advantage by predicting subsequent environmental changes. In the model plant Arabidopsis thaliana (Arabidopsis), our understanding of the complex genetic network among clock components has considerably increased during these past years. Modeling has predicted the possibility of additional component to systematically and functionally complete the clock system.

Functional interaction of the circadian clock and UV RESISTANCE LOCUS 8-controlled UV-B signaling pathways in Arabidopsis thaliana.

Circadian clocks regulate many molecular and physiological processes in Arabidopsis (Arabidopsis thaliana), allowing the timing of these processes to occur at the most appropriate time of the day in a 24-h period. The accuracy of timing relies on the synchrony of the clock and the environmental day/night cycle. Visible light is the most potent signal for such synchronization, but light-induced responses are also rhythmically attenuated (gated) by the clock.