Spatial and temporal expression of laccase in Coprinopsis cinerea using galectin promoters

Abstract

Galectins are ß-galactoside binding lectins defined by a conserved sequence. In mammals, there is a family of galectins that interact with glycoproteins in both extracellular and intracellular milieu and regulate various biological phenomena including cell growth, cell differentiation, cell adhesion, and apoptosis. Outside of the animal kingdom, genes for galectins are known in Arabidopsis and a few basidiomycetes. In fungi, galectins have been studied in detail in Coprinopsis cinerea. The C. cinerea galectins Cgl1 and Cgl2 are specific to the fruiting body. When nutrients are exhausted, Cgl2 is expressed under dark conditions in the mycelium at places of fruiting body initiation and primary hyphal knot formation. Cgl2 expression continues within the initial stages of fruiting body development till primordia formation is completed. In contrast, expression of Cgl1 starts later with the light-induced formation of secondary hyphal knots. Cgl1 expression also continues during primordia development to end at the stage of meiosis. In the genome, there is a gene for a third galectin (cgl3) but nothing is yet known about its expression. In this study, we establish the C. cinerea laccase gene lcc1 as a reporter gene to study spatial and temporal regulation of galectin gene promoters during fruiting body development.