Spontaneous circadian rhythms in a cold-adapted natural isolate of Aureobasidium pullulans

Abstract

Circadian systems enable organisms to synchronize their physiology to daily and seasonal environmental changes relying on endogenous pacemakers that oscillate with a period close to 24 h even in the absence of external timing cues. The oscillations are achieved by intracellular transcriptional/translational feedback loops thoroughly characterized for many organisms, but still little is known about the presence and characteristics of circadian clocks in fungi other than Neurospora crassa. We sought to characterize the circadian system of a natural isolate of Aureobasidium pullulans, a cold-adapted yeast bearing great biotechnological potential. A. pullulans formed daily concentric rings that were synchronized by light/dark cycles and were also formed in constant darkness with a period of 24.5 h. Moreover, these rhythms were temperature compensated, as evidenced by experiments conducted at temperatures as low as 10 °C. Finally, the expression of clock-essential genes, frequency, white collar-1, white collar-2 and vivid was confirmed. In summary, our results indicate the existence of a functional circadian clock in A. pullulans, capable of sustaining rhythms at very low temperatures and, based on the presence of conserved clock-gene homologues, suggest a molecular and functional relationship to well-described circadian systems.

The velvet protein Vel1 controls initial plant root colonization and conidia formation for xylem distribution in Verticillium wilt

“…Light response can be interconnected with temperature and circadian control in fungi [ 33 , 34 ]. Wild type V .…”

“…Light response can be interconnected with temperature and circadian control in fungi [33,34]. Wild type V. dahliae forms microsclerotia and aerial hyphae in response to light and dark cycles on SXM, resulting in a characteristic ring-like structure.…”

No Evidence That Homologs of Key Circadian Clock Genes Direct Circadian Programs of Development or mRNA Abundance in Verticillium dahliae

“…In N. crassa, short pulses of light trigger a rapid induction of frq transcription that result in the resetting of the clock (Crosthwaite et al, 1995). WC-1 is required for photoinduction of frq in response to light not only in N. crassa (Froehlich et al, 2002) but in other fungal species (Hevia et al, 2015;Traeger and Nowrousian, 2015;Franco et al, 2017). However, our results show that whereas V. dahliae photoreceptor-encoding genes Vdvvd and Vdcry-dash rapidly respond to light, Vdfrq expression is not light-induced.…”

“…Interestingly, FRQ is the least conserved of the clock proteins. While examples of functional frq-dependent circadian oscillators are present in the Leotiomycete Botrytis cinerea (Hevia et al, 2015) and in the Pezizomycete Pyronema confluens (Traeger and Nowrousian, 2015), other fungi, such as the Dothideomycete Aureobasidium pullulans, show no rhythmic frq expression, although they do display a circadian developmental rhythm (Franco et al, 2017). Circadian rhythms have also been demonstrated in species lacking a frq homolog, such as in Aspergillus flavus and Aspergillus nidulans (Greene et al, 2003).…”

Light/dark and temperature cycling modulate metabolic electron flow inPseudomonas aeruginosabiofilms

“…Circadian changes in gene expression and fluctuations in cellular differentiation have also been associated with biofilm formation in this organism (48). Other microbes that have been shown to form ring or band patterns that exhibit rhythmicity include P. putida, L. monocytogenes, K. aerogenes, and dimorphic and cold-adapted yeast (49)(50)(51)(52)(53). While some of these phenotypes require growth under light/dark or temperature cycling conditions, others occur autonomously.…”