Yunfeng Lei , Guodong Liu , Zhonghai Li , Liwei Gao , Yuqi Qin  , Yinbo Qu

Fungal Genetics and Biology 66 (2014) 44–53

ABSTRACT

Casein kinase CK2 is a ubiquitous and conserved phosphate transferase that is critical for the growth and development of eukaryotic cells. In Penicillium oxalicum, one catalytic subunit (CK2A) and two regulatory subunits (CK2B1 and CK2B2) of CK2 were annotated. In this study, CK2 regulatory subunit-defective mutants Dck2B1 and Dck2B2 were constructed to investigate the biological function of CK2 in P. oxalicum. The Dck2B1 strain exhibited minimal changes in morphogenesis and conidiation, whereas the Dck2B2 strain showed delayed conidial germination and drastically reduced conidiation compared with the parent strain. The defect in conidiation in Dck2B2 could be attributed to the reduced expression of transcription factor BrlA. Both Dck2B1 and Dck2B2 showed delayed autolysis in carbon-starvation medium compared with the parent strain. Cellulase and amylase production were decreased considerably in both mutants. The transcript abundances of the main extracellular glycoside hydrolase genes cel7A-2, bgl1, and amy15A, as well as those of three related transcriptional activators (i.e., ClrB, XlnR, and AmyR), were reduced or delayed in the mutants. Epistasis analysis suggested that CK2B1 and CK2B2 might function upstream of transcription factor CreA by inhibiting its repressing activity. In summary, CK2 plays important roles in development and extracellular enzyme production in P. oxalicum, with both unique and overlapping functions performed by the two regulatory subunits.