Phototropins do not alter accumulation of evening-phased circadian transcripts under blue light

Abstract

The circadian system induces rhythmic variation in a suite of biochemical and physiological processes that serve to optimise plant growth in diel cycles. To be of greatest utility, these rhythmic behaviors are coordinated with regular environmental changes such as the rising and setting of the sun. Photoreceptors, along with metabolites produced during photosynthesis, act to synchronise the internal timing mechanism with lighting cues. We have recently shown that phototropins help maintain robust rhythms of photosynthetic operating efficiency (wPSII or F q 0 /F m 0 ) under blue light, although rhythmic accumulation of morning-phased circadian transcripts in the nucleus was unaffected. Here we report that eveningphased nuclear clock transcripts were also unaffected. We also observe that rhythms of nuclear clock transcript accumulation are maintained in phototropin mutant plants under a fluctuating lighting regime that induced a loss of F q 0 /F m 0 rhythms.

Circadian rhythms are associated with variation in photosystem II function and photoprotective mechanisms

“…Recent studies also indicate that natural variation at the clock gene, GIGANTEA, affects cold tolerance (Xie et al, 2015) and growth patterns (de Montaigu et al, 2015), whereas in domesticated tomato, delayed circadian clock was selected during the process of domestication (Müller et al, 2016). Our results build upon the known regulation of PSII by the circadian clock (Dakhiya et al, 2017;Litthauer et al, 2015;Litthauer, Battle, & Jones, 2016;Noordally et al, 2013), by characterizing the genetic architecture of Fv′/Fm′, NPQ, and the components of NPQ in segregating lines, and by defining an association between these traits and quantitative variation in the circadian clock.…”

Daily Regulation of Key Metabolic Pathways in Two Seagrasses Under Natural Light Conditions

“…Different photic cues (e.g., day-length, intensity, spectral composition of sun light and solar position) may contribute to the entrainment of circadian clock of plants (Millar, 2004). These signals are perceived via three regulatory families of photoreceptors including phytochromes (PHY), which are sensitive to red/far-red, and cryptochromes (CRY) and phototropins (PHOT), which adsorb in the UV-blue light (Millar, 2003), although phototropins seems not to have a direct role in light input into the circadian clock (Jones, 2009;Litthauer et al, 2016). The ZEITLUPE (ZTL) family that belongs to the LOV domain photoreceptors is the third family of blue light photoreceptors in plants, with a central role in circadian clock and photoperiodic flowering (Song et al, 2014).…”

Compartmentation of photosynthesis gene expression between mesophyll and bundle sheath cells of C4maize is dependent on time of day

“…Our analysis shows that under moderate illumination and a constant light regime similar to those used in A. thaliana, barley and wheat to study circadian oscillations (Dakhiya et al, 2017;Litthauer et al, 2015Litthauer et al, , 2016Wittern et al, 2022) photosynthetic rates vary in maize. These findings are therefore consistent with the fact that photosynthesis in C 3 species is modulated by the circadian oscillator (Dodd et al, 2005) and our analysis of chlorophyll fluorescence quenching in maize supports this notion.…”