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Organisms track time of day through the function of cell-autonomous molecular clocks. In addition to a central clock located in the brain, molecular clocks are present in most peripheral tissues. Circadian clocks are coordinated within and across tissues, but the manner through which this coordination is achieved is not well understood. We reasoned that the ability to track in vivo molecular clock activity in specific tissues of the fruit fly, Drosophila melanogaster, would facilitate an investigation into the relationship between different clock-containing tissues. Previous efforts to monitor clock gene expression in single flies in vivo have used regulatory elements of several different clock genes to dictate expression of a luciferase reporter enzyme, the activity of which can be monitored using a luminometer. Although these reporter lines have been instrumental in our understanding of the circadian system, they generally lack cell specificity, making it difficult to compare molecular clock oscillations between different tissues. Here, we report the generation of several novel lines of flies that allow for inducible expression of a luciferase reporter construct for clock gene transcriptional activity. We find that these lines faithfully report circadian transcription, as they exhibit rhythmic luciferase activity that is dependent on a functional molecular clock. Furthermore, we take advantage of our reporter lines’ tissue specificity to demonstrate that peripheral molecular clocks are able to retain rhythmicity for multiple days under constant environmental conditions.
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Keeping time in the dark: Potato diel and circadian rhythmic gene expression reveals tissue‐specific circadian clocks
Abstract The circadian clock is an internal molecular oscillator and coordinates numerous physiological processes through regulation of molecular pathways. Tissue‐specific clocks connected by mobile signals have previously been found to run at different speeds inArabidopsis thalianatissues. However, tissue variation in circadian clocks in crop species is unknown. In this study, leaf and tuber global gene expression in cultivated potato under cycling and constant environmental conditions was profiled. In addition, we used a circadian‐regulated luciferase reporter construct to study tuber gene expression rhythms. Diel and circadian expression patterns were present among 17.9% and 5.6% of the expressed genes in the tuber. Over 500 genes displayed differential tissue specific diel phases. Intriguingly, few core circadian clock genes had circadian expression patterns, while all such genes were circadian rhythmic in cultivated tomato leaves. Furthermore, robust diel and circadian transcriptional rhythms were observed among detached tubers. Our results suggest alternative regulatory mechanisms and/or clock composition is present in potato, as well as the presence of tissue‐specific independent circadian clocks. We have provided the first evidence of a functional circadian clock in below‐ground storage organs, holding important implications for other storage root and tuberous crops.
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- Award ID(s):
- 1950376
- PAR ID:
- 10369148
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Plant Direct
- Volume:
- 6
- Issue:
- 7
- ISSN:
- 2475-4455
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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