Spontaneous circadian rhythms in a cold adapted native Aureobasidium pullulans

LORENA FRANCO; DIEGO LIBKIND; PAULO CANESSA; NICOLAS BELLORA; SEBASTIAN RISAU; PABLO GLEISER; LUIS LARRONDO; LUCIANO MARPEGAN

Perugia

Congreso; ISSY 2015, International Specialized Symposium on Yeasts; 2015

Circadian systems are found from cyanobacteria to mammals, and though they involve different genes in diverse organisms, the basic mechanisms of cellular circadian timekeeping are similar in all known circadian clocks. However, the circadian system in fungi is poorly described. The molecular clock was described in mutant strains of N. crassa under very specific growth conditions. Whereas in yeasts, it is not known if the molecular clock is present, and if so, how circadian phenotypes in these organisms could be exploited biotechnologically. We hypothesized that natural circadian traits are more likely to be retained by environmental strains rather than their experimental strains. Aureobasidium pullulans CRUB 1823, a psychrotolerant yeast with biotechnological potential, was isolated from natural sources, screened for spontaneous circadian phenotypes, and for expression of circadian clock genes (qPCR). Colonies displayed daily formation of concentric rings with morphology and frequency dependent on light exposure. Rings were present in cultures grown in 12hr/12hr light/dark cycles and persisted in constant darkness, indicating that ring formation is controlled by an endogenous circadian clock and light. Furthermore, a gene expression analysis revealed that A. pullulans express the N. crassa clock-genes frq, wc-1, wc-2, and vvd suggesting a conserved circadian clock.