Circadian Stress Regimes Affect the Circadian Clock and Cause Jasmonic Acid-Dependent Cell Death in Cytokinin-Deficient Arabidopsis Plants

Abstract

ORCID IDs: 0000-0002-9888-7003 (I.F.); 0000-0002-6299-347X (M.R.)The circadian clock helps plants measure daylength and adapt to changes in the day-night rhythm. We found that changes in the light-dark regime triggered stress responses, eventually leading to cell death, in leaves of Arabidopsis thaliana plants with reduced cytokinin levels or defective cytokinin signaling. Prolonged light treatment followed by a dark period induced stress and cell death marker genes while reducing photosynthetic efficiency. This response, called circadian stress, is also characterized by altered expression of clock and clock output genes. In particular, this treatment strongly reduced the expression of CIRCADIAN CLOCK ASSOCIATED1 (CCA1) and LATE ELONGATED HYPOCOTYL (LHY). Intriguingly, similar changes in gene expression and cell death were observed in clock mutants lacking proper CCA1 and LHY function. Circadian stress caused strong changes in reactive oxygen species-and jasmonic acid (JA)-related gene expression. The activation of the JA pathway, involving the accumulation of JA metabolites, was crucial for the induction of cell death, since the cell death phenotype was strongly reduced in the jasmonate resistant1 mutant background. We propose that adaptation to circadian stress regimes requires a normal cytokinin status which, acting primarily through the AHK3 receptor, supports circadian clock function to guard against the detrimental effects of circadian stress.

Regulation of Banana Phytoene Synthase (MaPSY) Expression, Characterization and Their Modulation under Various Abiotic Stress Conditions

“…JA and its derivatives such as methyl jasmonate (MeJA) are reported to be involved in various plant biological activities including cell division, fruit growth and ripening (Creelman and Mullet, 1997). It also plays an important role in plant adaptation during abiotic stresses (Clarke et al, 2009; Yoon et al, 2009; Brossa et al, 2011; Nitschke et al, 2016). …”

Role of circadian gene Clock during differentiation of mouse pluripotent stem cells

“…Circadian rhythm is a fundamental biological system in humans, animals and plants that regulates various physiological functions such as sleep–wake cycle, energy metabolism, cell division, post-transcriptional regulation (Koike et al, 2012; Cardinal-Aucoin and Steel, 2016; Lopez-Minguez et al, 2016; McAlpine and Swirski, 2016; Nitschke et al, 2016), and endocrine system (Gachon et al, 2004; Lowrey and Takahashi, 2004). The master circadian clock, located in the suprachiasmatic nucleus (SCN), is an essential activator of downstream molecular events critical to the generation of circadian rhythms (Dunlap, 1999).…”

Analysis of catalase mutants underscores the essential role of CATALASE2 for plant growth and day length‐dependent oxidative signalling

“…Similar to LD‐dependent lesion formation in cat2 (Chaouch et al, ), ozone‐triggered lesions in Arabidopsis are more easily induced by equal‐time exposure in LD compared with SD (Dghim et al, ). Such effects may be related to circadian clock rhythms, which have been reported to interact with oxidative stress and related phytohormone signalling (Nitschke et al, ). Here, by using a short‐term exposure to oxidative stress of intracellular origin, we have shown that gene expression responses in leaves are strongly dependent on the history of the plant, and that this cannot be explained by day length‐dependent differences in CAT3 expression.…”